Children born after assisted reproduction more commonly carry a mitochondrial genotype associating with low birthweight.

Children conceived through assisted reproductive technologies (ART) have an elevated risk of lower birthweight, yet the underlying cause remains unclear. Our study explores mitochondrial DNA (mtDNA) variants as contributors to birthweight differences by impacting mitochondrial function during prenatal development. We deep-sequenced the mtDNA of 451 ART and spontaneously conceived (SC) individuals, 157 mother-child pairs and 113 individual oocytes from either natural menstrual cycles or after ovarian stimulation (OS) and find that ART individuals carried a different mtDNA genotype than SC individuals, with more de novo non-synonymous variants. These variants, along with rRNA variants, correlate with lower birthweight percentiles, independent of conception mode. Their higher occurrence in ART individuals stems from de novo mutagenesis associated with maternal aging and OS-induced oocyte cohort size. Future research will establish the long-term health consequences of these changes and how these findings will impact the clinical practice and patient counselling in the future.

At age 9, the methylome of assisted reproductive technology children that underwent embryo culture in different media is not significantly different on a genome-wide scale.

STUDY QUESTION: Can we detect DNA methylation differences between ART children that underwent embryo culture in different media? SUMMARY ANSWER: We identified no significant differences in site-specific or regional DNA methylation between the different culture medium groups. WHAT IS KNOWN ALREADY: Embryo culture in G3 or K-SICM medium leads to differences in embryonic, neonatal and childhood outcomes, including growth and weight. The methylome may mediate this association as the period of in vitro culture of ART treatments coincides with epigenetic reprogramming. STUDY DESIGN, SIZE, DURATION: This study was conducted as a follow-up to a previous culture medium comparison study in which couples were pseudo-randomized to embryo culture in G3 or K-SICM medium. Of the resultant singletons, 120 (n = 65 G3, n = 55 K-SICM), were recruited at age 9. PARTICIPANTS/MATERIALS, SETTING, METHODS: The ART children provided a saliva sample from which the methylome was analysed using the Infinium MethylationEPIC array. After quality and context filtering, 106 (n = 57 G3, n = 49 K-SICM) samples and 659 708 sites were retained for the analyses. Differential methylation analyses were conducted using mixed effects linear models corrected for age, sex, sample plate and cell composition. These were applied to all cytosine-guanine dinucleotide (CpG) sites, various genomic regions (genes, promoters, CpG Islands (CGIs)) and as a targeted analysis of imprinted genes and birth weight-associated CpG sites. Differential variance was assessed using the improved epigenetic variable outliers for risk prediction analysis (iEVORA) algorithm and methylation outliers were identified using a previously defined threshold (upper or lower quartile plus or minus three times the interquartile range, respectively). MAIN RESULTS AND THE ROLE OF CHANCE: After correcting for multiple testing, we did not identify any significantly differentially methylated CpG sites, genes, promoters or CGIs between G3 and K-SICM children despite a lenient corrected P-value threshold of 0.1. Targeted analyses of (sites within) imprinted genes and birth weight-associated sites also did not identify any significant differences. The number of DNA methylation outliers per sample was comparable between the culture medium groups. iEVORA identified 101 differentially variable CpG sites of which 94 were more variable in the G3 group. LARGE SCALE DATA: Gene Expression Omnibus (GEO) GSE196432. LIMITATIONS, REASONS FOR CAUTION: To detect significant methylation differences with a magnitude of <10% between the groups many more participants would be necessary; however, the clinical relevance of such small differences is unclear. WIDER IMPLICATIONS OF THE FINDINGS: The results of this study are reassuring, suggesting that if there is an effect of the culture medium on DNA methylation (and methylation-mediated diseases risk), it does not differ between the two media investigated here. The findings concur with other methylome studies of ART neonates and children that underwent embryo culture in different media, which also found no significant methylome differences. STUDY FUNDING/COMPETING INTEREST(S): Study funded by March of Dimes (6-FY13-153), EVA (Erfelijkheid Voortplanting & Aanleg) specialty programme (grant no. KP111513) of Maastricht University Medical Centre (MUMC+) and the Horizon 2020 innovation (ERIN) (grant no. EU952516) of the European Commission. The authors do not report any conflicts of interest relevant to this study. TRIAL REGISTRATION NUMBER: Dutch Trial register-NL4083.

Methylome-wide analysis of IVF neonates that underwent embryo culture in different media revealed no significant differences.

A growing number of children born are conceived through in vitro fertilisation (IVF), which has been linked to an increased risk of adverse perinatal outcomes, as well as altered growth profiles and cardiometabolic differences in the resultant individuals. Some of these outcomes have also been shown to be influenced by the use of different IVF culture media and this effect is hypothesised to be mediated epigenetically, e.g. through the methylome. As such, we profiled the umbilical cord blood methylome of IVF neonates that underwent preimplantation embryo development in two different IVF culture media (G5 or HTF), using the Infinium Human Methylation EPIC BeadChip. We found no significant methylation differences between the two groups in terms of: (i) systematic differences at CpG sites or regions, (ii) imprinted sites/genes or birth weight-associated sites, (iii) stochastic differences presenting as DNA methylation outliers or differentially variable sites, and (iv) epigenetic gestational age acceleration.

Lifestyle intervention prior to IVF does not improve embryo utilization rate and cumulative live birth rate in women with obesity: a nested cohort study.

STUDY QUESTION: Does lifestyle intervention consisting of an energy-restricted diet, enhancement of physical activity and motivational counseling prior to IVF improve embryo utilization rate (EUR) and cumulative live birth rate (CLBR) in women with obesity? SUMMARY ANSWER: A 6-month lifestyle intervention preceding IVF improved neither EUR nor CLBR in women with obesity in the first IVF treatment cycle where at least one oocyte was retrieved. WHAT IS KNOWN ALREADY: A randomized controlled trial (RCT) evaluating the efficacy of a low caloric liquid formula diet (LCD) preceding IVF in women with obesity was unable to demonstrate an effect of LCD on embryo quality and live birth rate: in this study, only one fresh embryo transfer (ET) or, in case of freeze-all strategy, the first transfer with frozen-thawed embryos was reported. We hypothesized that any effect on embryo quality of a lifestyle intervention in women with obesity undergoing IVF treatment is better revealed by EUR and CLBR after transfer of all fresh and frozen-thawed embryos. STUDY DESIGN SIZE DURATION: This is a nested cohort study within an RCT, the LIFEstyle study. The original study examined whether a 6-month lifestyle intervention prior to infertility treatment in women with obesity improved live birth rate, compared to prompt infertility treatment within 24 months after randomization. In the original study between 2009 and 2012, 577 (three women withdrew informed consent) women with obesity and infertility were assigned to a lifestyle intervention followed by infertility treatment (n = 289) or to prompt infertility treatment (n = 285). PARTICIPANTS/MATERIALS SETTING METHODS: Only participants from the LIFEstyle study who received IVF treatment were eligible for the current analysis. In total, 137 participants (n = 58 in the intervention group and n = 79 in the control group) started the first cycle. In 25 participants, the first cycle was cancelled prior to oocyte retrieval mostly due to poor response. Sixteen participants started a second or third consecutive cycle. The first cycle with successful oocyte retrieval was used for this analysis, resulting in analysis of 51 participants in the intervention group and 72 participants in the control group. Considering differences in embryo scoring methods and ET day strategy between IVF centers, we used EUR as a proxy for embryo quality. EUR was defined as the proportion of inseminated/injected oocytes per cycle that was transferred or cryopreserved as an embryo. Analysis was performed per cycle and per oocyte/embryo. CLBR was defined as the percentage of participants with at least one live birth from the first fresh and subsequent frozen-thawed ET(s). In addition, we calculated the Z-score for singleton neonatal birthweight and compared these outcomes between the two groups. MAIN RESULTS AND THE ROLE OF CHANCE: The overall mean age was 31.6 years and the mean BMI was 35.4 ± 3.2 kg/m2 in the intervention group, and 34.9 ± 2.9 kg/m2 in the control group. The weight change at 6 months was in favor of the intervention group (mean difference in kg vs the control group: -3.14, 95% CI: -5.73 to -0.56). The median (Q25; Q75) number of oocytes retrieved was 4.00 (2.00; 8.00) in the intervention group versus 6.00 (4.00; 9.75) in the control group, and was not significantly different, as was the number of oocytes inseminated/injected (4.00 [2.00; 8.00] vs 6.00 [3.00; 8.75]), normal fertilized embryos (2.00 [0.50; 5.00] vs 3.00 [1.00; 5.00]) and the number of cryopreserved embryos (2.00 [1.25; 4.75] vs 2.00 [1.00; 4.00]). The median (Q25; Q75) EUR was 33.3% (12.5%; 60.0%) in the intervention group and 33.3% (16.7%; 50.0%) in the control group in the per cycle analysis (adjusted B: 2.7%, 95% CI: -8.6% to 14.0%). In the per oocyte/embryo analysis, in total, 280 oocytes were injected or inseminated in the intervention group, 113 were utilized (transferred or cryopreserved, EUR = 40.4%); in the control group, EUR was 30.8% (142/461). The lifestyle intervention did not significantly improve EUR (adjusted odds ratio [OR]: 1.36, 95% CI: 0.94-1.98) in the per oocyte/embryo analysis, taking into account the interdependency of the oocytes per participant. CLBR was not significantly different between the intervention group and the control group after adjusting for type of infertility (male factor and unexplained) and smoking (27.5% vs 22.2%, adjusted OR: 1.03, 95% CI: 0.43-2.47). Singleton neonatal birthweight and Z-score were not significantly different between the two groups. LIMITATIONS REASONS FOR CAUTION: This study is a nested cohort study within an RCT, and no power calculation was performed. The randomization was not stratified for indicated treatment, and although we corrected our analyses for baseline differences, there may be residual confounding. The limited absolute weight loss and the short duration of the lifestyle intervention might be insufficient to affect EUR and CLBR. WIDER IMPLICATIONS OF THE FINDINGS: Our data do not support the hypothesis of a beneficial short-term effect of lifestyle intervention on EUR and CLBR after IVF in women with obesity, although more studies are needed as there may be a potential clinically relevant effect on EUR. STUDY FUNDING/COMPETING INTERESTS: The study was supported by a grant from ZonMw, the Dutch Organization for Health Research and Development (50-50110-96-518). A.H. has received an unrestricted educational grant from Ferring pharmaceuticals BV, The Netherlands. B.W.J.M. is supported by an NHMRC Investigator grant (GNT1176437). B.W.J.M. reports consultancy for Guerbet, has been a member of the ObsEva advisory board and holds Stock options for ObsEva. B.W.J.M. has received research funding from Guerbet, Ferring and Merck. F.J.M.B. reports personal fees from membership of the external advisory board for Merck Serono and a research support grant from Merck Serono, outside the submitted work. TRIAL REGISTRATION NUMBER: The LIFEstyle RCT was registered at the Dutch trial registry (NTR 1530). https://www.trialregister.nl/trialreg/admin/rctview.asp?TC=1530.

Comparison of DNA methylation patterns of parentally imprinted genes in placenta derived from IVF conceptions in two different culture media.

STUDY QUESTION: Is there a difference in DNA methylation status of imprinted genes in placentas derived from IVF conceptions where embryo culture was performed in human tubal fluid (HTF) versus G5 culture medium? SUMMARY ANSWER: We found no statistically significant differences in the mean DNA methylation status of differentially methylated regions (DMRs) associated with parentally imprinted genes in placentas derived from IVF conceptions cultured in HTF versus G5 culture medium. WHAT IS KNOWN ALREADY: Animal studies indicate that the embryo culture environment affects the DNA methylation status of the embryo. In humans, birthweight is known to be affected by the type of embryo culture medium used. The effect of embryo culture media on pregnancy, birth and child development may thus be mediated by differential methylation of parentally imprinted genes in the placenta. STUDY DESIGN, SIZE, DURATION: To identify differential DNA methylation of imprinted genes in human placenta derived from IVF conceptions exposed to HTF or G5 embryo culture medium, placenta samples (n = 43 for HTF, n = 54 for G5) were collected between 2010 and 2012 s as part of a multi-center randomized controlled trial in the Netherlands comparing these embryo culture media. Placenta samples from 69 naturally conceived (NC) live births were collected during 2008-2013 in the Netherlands as reference material. PARTICIPANTS/MATERIALS, SETTING, METHODS: To identify differential DNA methylation of imprinted genes, we opted for an amplicon-based sequencing strategy on an Illumina MiSeq sequencing platform. DNA was isolated and 34 DMRs associated with well-defined parentally imprinted genes were amplified in a two-step PCR before sequencing using MiSeq technology. Sequencing data were analyzed in a multivariate fashion to eliminate possible confounding effects. MAIN RESULTS AND THE ROLE OF CHANCE: We found no statistically significant differences in the mean DNA methylation status of any of the imprinted DMRs in placentas derived from IVF conceptions cultured in HTF or G5 culture medium. We also did not observe any differences in the mean methylation status per amplicon nor in the variance in methylation per amplicon between the two culture medium.groups. A separate surrogate variable analysis also demonstrated that the IVF culture medium was not associated with the DNA methylation status of these DMRs. The mean methylation level and variance per CpG was equal between HTF and G5 placenta. Additional comparison of DNA methylation status of NC placenta samples revealed no statistically significant differences in mean amplicon and CpG methylation between G5, HTF and NC placenta; however, the number of placenta samples exhibiting outlier methylation levels was higher in IVF placenta compared to NC (P < 0.00001). Also, we were able to identify 37 CpG sites that uniquely displayed outlier methylation in G5 placentas and 32 CpG sites that uniquely displayed outlier methylation in HTF. In 8/37 (G5) and 4/32 (HTF) unique outliers CpGs, a medium-specific unique outlier could be directly correlated to outlier methylation of the entire amplicon. LIMITATIONS, REASONS FOR CAUTION: Due to practical reasons, not all placentas were collected during the trial, and we collected the placentas from natural conceptions from a different cohort, potentially creating bias. We limited ourselves to the DNA methylation status of 34 imprinted DMRs, and we studied only the placenta and no other embryo-derived tissues. WIDER IMPLICATIONS OF THE FINDINGS: It has often been postulated, but has yet to be rigorously tested, that imprinting mediates the effects of embryo culture conditions on pregnancy, birth and child development in humans. Since we did not detect any statistically significant effects of embryo culture conditions on methylation status of imprinted genes in the placenta, this suggests that other unexplored mechanisms may underlie these effects. The biological and clinical relevance of detected outliers with respect to methylation levels of CpGs and DMR require additional analysis in a larger sample size as well. Given the importance and the growing number of children born through IVF, research into these molecular mechanisms is urgently needed. STUDY FUNDING/COMPETING INTEREST(S): This study was funded by the March of Dimes grant number #6-FY13-153. The authors have no conflicts of interest. TRIAL REGISTRATION NUMBER: Placental biopsies were obtained under Netherlands Trial Registry number 1979 and 1298.

Reduced oxygen concentration during human IVF culture improves embryo utilization and cumulative pregnancy rates per cycle.

STUDY QUESTION: Do different oxygen levels during human IVF embryo culture affect embryo utilization, cumulative IVF success rates per cycle and neonatal birthweight? SUMMARY ANSWER: After 2 days of culture, a lower oxygen level (5%) leads to more good-quality embryos and more embryos that can be cryopreserved, and thereby to a higher cumulative live birth rate per cycle when compared to embryo culture in 20% oxygen, while birthweights are similar. WHAT IS KNOWN ALREADY: Several studies have compared IVF outcome parameters after embryo culture in a more physiological level of 5% oxygen and the atmospheric level of 20%. Although there is consensus that embryo development improves in 5% oxygen, effects on pregnancy and live birth rates are mainly seen in blastocyst, but not cleavage-stage transfers. A major drawback of these studies is that only fresh embryo transfers were included, not taking additional frozen-thawed transfers from these cycles into account. This might have underestimated the effects of oxygen level, especially in cleavage-stage embryo transfers. Furthermore, little is known about the effect of oxygen level during culture on birthweight. STUDY DESIGN SIZE DURATION: This is a cohort study in 871 consecutive patients who had an IVF cycle between January 2012 and December 2013, and 5-7 years follow-up to allow transfer of frozen-thawed embryos. Based on daily availability of positions in the incubators, all oocytes and embryos of one cycle were allocated to one of the three incubators with traditional ambient oxygen levels (6% CO2 and 20% O2 in air), or to a fourth incubator that was adjusted to have low oxygen levels of 5% (6% CO2, 5% O2 and 89% N2). Embryos were cultured under 5 or 20% oxygen until Day 2 or 3, when embryos were transferred or cryopreserved, respectively. Clinical and other laboratory procedures were similar in both groups. PARTICIPANTS/MATERIALS SETTING METHODS: To compare embryo characteristics and (cumulative) pregnancy outcomes between the two oxygen groups, for each patient only the first cycle in the study period was included in the analysis, resulting in 195 cycles in the 5% group (1627 oocytes) and 676 in the 20% oxygen group (5448 oocytes). Embryo characteristics were analysed per cycle and per embryo and were corrected for maternal age, cycle rank order, fertilization method (IVF or ICSI) and cause of subfertility. Perinatal data from the resulting singletons (n = 124 after fresh and 45 after frozen-thawed embryo transfer) were collected from delivery reports from the hospitals or midwife practices. MAIN RESULTS AND THE ROLE OF CHANCE: In the 5% oxygen group, there were significantly more embryos of good quality (45.8 versus 30.9% in the 20% group, adjusted odds ratio (OR) [95% CI] = 1.9 [1.6-2.4]). This did not result in higher live birth rates per cycle, but after fresh transfers more good-quality spare embryos could be cryopreserved (46.1 versus 29.7%, adjusted OR [95% CI] = 2.0 [1.7-2.5]).After a follow-up period of 5-7 years, in which 82.4% of the cryopreserved embryos from the 5% oxygen group and 85.4% from the 20% oxygen group were thawed, the percentage of patients with at least one live birth resulting from the study cycle was significantly higher in the low oxygen group (adjusted OR [95% CI] = 1.5 [1.01-2.2]). In 124 live born singletons from fresh embryo transfers and in 45 from transfers of cryopreserved embryos, birthweight was similar in both oxygen groups after correction for confounding factors. LIMITATIONS REASONS FOR CAUTION: This is a retrospective study, and treatment allocation was not randomised. The study was not powered for a predefined birthweight difference. With the number of live births in our study, small differences in birthweight might not have been detected. The selection of embryos to be cryopreserved was based on embryo morphology criteria that might be different in other clinics. WIDER IMPLICATIONS OF THE FINDINGS: Improved embryo utilization by more cryopreservation leading to higher cumulative live birth rates per cycle favours the use of 5% instead of 20% oxygen during human IVF embryo culture. This study also demonstrates that for comparison of different IVF treatment regimens, the cumulative outcome, including transfers of fresh and frozen-thawed embryos, is to be preferred instead of analysis of fresh embryo transfers only. STUDY FUNDING/COMPETING INTERESTS: No external funding was received for this study. None of the authors has a conflict of interest to declare. TRIAL REGISTRATION NUMBER: NA.

Anti-oxidative function of follicular fluid HDL and outcomes of modified natural cycle-IVF.

High density lipoproteins (HDL) are the main cholesterol carriers in follicular fluid (FF), the natural environment of oocyte development. Additionally, HDL have critical biological functions such as anti-oxidative capacity, which have not been studied in reproduction. Therefore, this study aimed to investigate whether the anti-oxidative function of FF-HDL is associated with fertility outcomes. From 253 women undergoing modified natural cycle (MNC)- IVF at a single academic centre FF and plasma were collected (n = 375 cycles). Anti-oxidative function of FF was mainly attributable to HDL (n = 8; 83%). FF-HDL had a higher anti-oxidative function than plasma HDL (n = 19, P < 0.001) coinciding with increased vitamin E and sphingosine 1 phosphate content (P = 0.028 each). Proteomic analysis indicated no significant differences in major anti-oxidative proteins such as paraoxonase 1, apolipoprotein (apo) A-I or apoA-IV between FF-HDL and matched plasma-HDL (n = 5), while apoC-III, apoE and apoC-II were relatively lower in FF-HDL. Finally, FF-HDL anti-oxidative function was related to a decrease in the odds of the oocyte undergoing normal fertilization, an association that persisted after adjustment for confounders (odds ratio 0.97 (0.93-1), P = 0.041). In conclusion, FF-HDL has considerable anti-oxidative properties that might be relevant for embryo quality.

Preconceptional Maternal Bile Acids and Birth Weight of Neonates.

Preconceptional maternal bile acid species are significantly associated with birth weight of the offspring.

The treatment of post-hysterectomy vaginal vault prolapse: a systematic review and meta-analysis.

INTRODUCTION AND HYPOTHESIS: The treatment of post-hysterectomy vaginal vault prolapse (VVP) has been investigated in several randomized clinical trials (RCTs), but a systematic review of the topic is still lacking. The aim of this study is to compare the effectiveness of treatments for VVP. METHODS: We performed a systematic review and meta-analysis of the literature on the treatment of VVP found in PubMed and Embase. Reference lists of identified relevant articles were checked for additional articles. A network plot was constructed to illustrate the geometry of the network of the treatments included. Only RCTs reporting on the treatment of VVP were eligible, conditional on a minimum of 30 participants with VVP and a follow-up of at least 6 months. RESULTS: Nine RCTs reporting 846 women (ranging from 95 to 168 women) met the inclusion criteria. All surgical techniques were associated with good subjective results, and without differences between the compared technique, with the exception of the comparison of vaginal mesh (VM) vs laparoscopic sacrocolpopexy (LSC). LSC is associated with a higher satisfaction rate. The anatomical results of the sacrocolpopexy (laparoscopic, robotic [RSC]. and abdominal [ASC]) are the best (62-91%), followed by the VM. However, the ranges of the anatomical outcome of VM were wide (43-97%). The poorest results are described for the sacrospinal fixation (SSF; 35-81%), which also correlates with the higher reoperation rate for pelvic organ prolapse (POP; 5-9%). The highest percentage of complications were reported after ASC (2-19%), VM (6-29%), and RSC (54%). Mesh exposure was seen most often after VM (8-21%). The rate of reoperations carried out because of complications, recurrence prolapse, and incontinence of VM was 13-22%. Overall, sacrocolpopexy reported the best results at follow-up, with an outlier of one trial reporting the highest reoperation rate for POP (11%). The results of the RSC are too small to make any conclusion, but LSC seems to be preferable to ASC. CONCLUSIONS: A comparison of techniques was difficult because of heterogeneity; therefore, a network meta-analysis was not possible. All techniques have proved to be effective. The reported differences between the techniques were negligible. Therefore, a standard treatment for VVP could not be given according to this review.

Influence of embryo culture medium (G5 and HTF) on pregnancy and perinatal outcome after IVF: a multicenter RCT.

STUDY QUESTION: Does embryo culture medium influence pregnancy and perinatal outcome in IVF? SUMMARY ANSWER: Embryo culture media used in IVF affect treatment efficacy and the birthweight of newborns. WHAT IS KNOWN ALREADY: A wide variety of culture media for human preimplantation embryos in IVF/ICSI treatments currently exists. It is unknown which medium is best in terms of clinical outcomes. Furthermore, it has been suggested that the culture medium used for the in vitro culture of embryos affects birthweight, but this has never been demonstrated by large randomized trials. STUDY DESIGN, SIZE, DURATION: We conducted a multicenter, double-blind RCT comparing the use of HTF and G5 embryo culture media in IVF. Between July 2010 and May 2012, 836 couples (419 in the HTF group and 417 in the G5 group) were included. The allocated medium (1:1 allocation) was used in all treatment cycles a couple received within 1 year after randomization, including possible transfers with frozen-thawed embryos. The primary outcome was live birth rate. PARTICIPANTS/MATERIALS, SETTING, METHODS: Couples that were scheduled for an IVF or an ICSI treatment at one of the six participating centers in the Netherlands or their affiliated clinics. MAIN RESULTS AND THE ROLE OF CHANCE: The live birth rate was higher, albeit nonsignificantly, in couples assigned to G5 than in couples assigned to HTF (44.1% (184/417) versus 37.9% (159/419); RR: 1.2; 95% confidence interval (CI): 0.99-1.37; P = 0.08). Number of utilizable embryos per cycle (2.8 ± 2.3 versus 2.3 ± 1.8; P < 0.001), implantation rate after fresh embryo transfer (20.2 versus 15.3%; P < 0.001) and clinical pregnancy rate (47.7 versus 40.1%; RR: 1.2; 95% CI: 1.02-1.39; P = 0.03) were significantly higher for couples assigned to G5 compared with those assigned to HTF. Of the 383 live born children in this trial, birthweight data from 380 children (300 singletons (G5: 163, HTF: 137) and 80 twin children (G5: 38, HTF: 42)) were retrieved. Birthweight was significantly lower in the G5 group compared with the HTF group, with a mean difference of 158 g (95% CI: 42-275 g; P = 0.008). More singletons were born preterm in the G5 group (8.6% (14/163) versus 2.2% (3/137), but singleton birthweight adjusted for gestational age and gender (z-score) was also lower in the G5 than in the HTF group (-0.13 ± 0.08 versus 0.17 ± 0.08; P = 0.008). LIMITATIONS, REASONS FOR CAUTION: This study was powered to detect a 10% difference in live births while a smaller difference could still be clinically relevant. The effect of other culture media on perinatal outcome remains to be determined. WIDER IMPLICATIONS OF THE FINDINGS: Embryo culture media used in IVF affect not only treatment efficacy but also perinatal outcome. This suggests that the millions of human embryos that are cultured in vitro each year are sensitive to their environment. These findings should lead to increased awareness, mechanistic studies and legislative adaptations to protect IVF offspring during the first few days of their existence. STUDY FUNDING/COMPETING INTERESTS: This project was partly funded by The NutsOhra foundation (Grant 1203-061) and March of Dimes (Grant 6-FY13-153). The authors declare no conflict of interest. TRIAL REGISTRATION NUMBER: NTR1979 (Netherlands Trial Registry). TRIAL REGISTRATION DATE: 1 September 2009. DATE OF FIRST PATIENT'S ENROLMENT: 18 July 2010.

Differences in Strength and Timing of the mtDNA Bottleneck between Zebrafish Germline and Non-germline Cells.

We studied the mtDNA bottleneck in zebrafish to elucidate size, timing, and variation in germline and non-germline cells. Mature zebrafish oocytes contain, on average, 19.0 × 10(6) mtDNA molecules with high variation between oocytes. During embryogenesis, the mtDNA copy number decreases to ∼170 mtDNA molecules per primordial germ cell (PGC), a number similar to that in mammals, and to ∼50 per non-PGC. These occur at the same developmental stage, implying considerable variation in mtDNA copy number in (non-)PGCs of the same female, dictated by variation in the mature oocyte. The presence of oocytes with low mtDNA numbers, if similar in humans, could explain how (de novo) mutations can reach high mutation loads within a single generation. High mtDNA copy numbers in mature oocytes are established by mtDNA replication during oocyte development. Bottleneck differences between germline and non-germline cells, due to early differentiation of PGCs, may account for different distribution patterns of familial mutations.

Ammonium accumulation in commercially available embryo culture media and protein supplements during storage at 2-8°C and during incubation at 37°C.

STUDY QUESTION: Does ammonium accumulate in commercially available culture media and protein supplements used for in vitro development of human pre-implantation embryos during storage and incubation? SUMMARY ANSWER: Ammonium accumulates in ready-to-use in vitro fertilization (IVF) culture media during storage at 2-8°C and in ready-to-use IVF culture media and protein supplements during incubation at 37°C. WHAT IS KNOWN ALREADY: Both animal and human studies have shown that the presence of ammonium in culture medium has detrimental effects on embryonic development and pregnancy rate. It is, therefore, important to assess the amount of ammonium accumulation in ready-to-use IVF culture media under conditions that are common in daily practice. STUDY DESIGN, SIZE, DURATION: Ammonium accumulation was investigated in 15 ready-to-use media, 11 protein-free media and 8 protein supplements. PARTICIPANTS/MATERIALS, SETTING, METHODS: Ammonium was measured by the use of an enzymatic method with glutamate dehydrogenase. To simulate the storage and incubation conditions during IVF treatments, ammonium concentrations were measured at different time-points during storage at 2-8°C for 6 weeks and during incubation at 37°C for 4 days. MAIN RESULTS AND THE ROLE OF CHANCE: All ready-to-use, i.e. protein supplemented, culture media showed ammonium accumulation during storage for 6 weeks (ranging from 9.2 to 99.8 µM) and during incubation for 4 days (ranging from 8.4 to 138.6 µM), resulting in levels that might affect embryo development. The protein supplements also showed ammonium accumulation, while the culture media without protein supplementation did not. The main sources of ammonium buildup in ready-to-use culture media were unstable glutamine and the protein supplements. No additional ammonium buildup was found during incubation when using an oil overlay or with the presence of an embryo in the culture droplet. LIMITATIONS, REASONS FOR CAUTION: In addition to the unstable glutamine and the protein supplements, other free amino acids might contribute to the ammonium buildup. We did not investigate the deterioration of other components in the media. WIDER IMPLICATIONS OF THE FINDINGS: Break-down of components into ammonium is more pronounced during incubation at 37°C, however, it is not negligible during storage at 2-8°C. This results in increasing ammonium levels in culture media over time that may affect embryo development. Therefore, it is important that the use of free l-glutamine in human embryo culture media is stopped and that the use of protein supplements is thoroughly evaluated. STUDY FUNDING/COMPETING INTERESTS: No funding or no competing interests declared. TRIAL REGISTRATION NUMBER: Not applicable.

Differences in gene expression profiles between human preimplantation embryos cultured in two different IVF culture media.

STUDY QUESTION: Is gene expression in human preimplantation embryos affected by the medium used for embryo culture in vitro during an IVF treatment? SUMMARY ANSWER: Six days of in vitro culture of human preimplantation embryos resulted in medium-dependent differences in expression level of genes involved in apoptosis, protein degradation, metabolism and cell-cycle regulation. WHAT IS KNOWN ALREADY: Several human studies have shown an effect of culture medium on embryo development, pregnancy outcome and birthweight. However, the underlying mechanisms in human embryos are still unknown. In animal models of human development, it has been demonstrated that culture of preimplantation embryos in vitro affects gene expression. In humans, it has been found that culture medium affects gene expression of cryopreserved embryos that, after thawing, were cultured in two different media for 2 more days. STUDY DESIGN, SIZE, DURATION: In a multicenter trial, women were randomly assigned to two culture medium groups [G5 and human tubal fluid (HTF)]. Data on embryonic development were collected for all embryos. In one center, embryos originating from two pronuclei (2PN) zygotes that were not selected for transfer or cryopreservation on Day 2 or 3 because of lower morphological quality, were cultured until Day 6 and used in this study, if couples consented. PARTICIPANTS/MATERIALS, SETTING, METHODS: Ten blastocysts each from the G5 and HTF study groups, matched for fertilization method, maternal age and blastocyst quality, were selected and their mRNA was isolated and amplified. Embryos were examined individually for genome-wide gene expression using Agilent microarrays and PathVisio was used to identify the pathways that showed a culture medium-dependent activity. MAIN RESULTS AND THE ROLE OF CHANCE: Expression of 951 genes differed significantly (P < 0.01) between the G5 and HTF groups. Eighteen pathways, involved in apoptosis, metabolism, protein processing and cell-cycle regulation, showed a significant overrepresentation of differentially expressed genes. The DNA replication, G1 to S cell-cycle control and oxidative phosphorylation pathways were up-regulated in the G5 group compared with the HTF group. This is in agreement with the morphological assessment of the 1527 embryos (originating from 2PN zygotes), which showed that embryos consisted of more cells on Day 2 (3.73 ± 1.30 versus 3.40 ± 1.35, P < 0.001) and Day 3 (7.00 ± 2.41 versus 5.84 ± 2.36, P < 0.001) in the G5 group when compared with the HTF group. Furthermore, the implantation rate was significantly higher in the G5 group compared with the HTF group (26.7% versus 14.7%, P = 0.002) after transfer on the second or the third day after fertilization. LIMITATIONS, REASONS FOR CAUTION: Despite careful matching of the embryos, it cannot be excluded that the differences observed between the study groups are caused by factors that we did not investigate. Extrapolation of these results to embryos used for transfer demands caution as in the present study embryos that were not selected for either embryo transfer or cryopreservation have been used for the culture experiment until Day 6. WIDER IMPLICATIONS OF THE FINDINGS: This study shows that gene expression in human preimplantation embryos is altered by the culture medium used during IVF treatment and provides insight into the biological pathways that are affected. Whether these changes in gene expression have any long-term effects on children born after IVF remains unknown. However, it is possible that early adaptations of the preimplantation embryo to its environment persist during fetal and post-natal development. STUDY FUNDING/COMPETING INTERESTS: No funding and no competing interests declared. TRIAL REGISTRATION NUMBER: Not applicable.

Age of G-1 PLUS v5 embryo culture medium is inversely associated with birthweight of the newborn.

STUDY QUESTION: Does age of G-1 PLUS v5 embryo culture medium affect IVF outcome? SUMMARY ANSWER: Birthweight of singletons born after IVF showed an inverse association with age of the embryo culture medium, while no association was found between age of culture medium and fertilization rate, embryonic development or ongoing pregnancy. WHAT IS KNOWN ALREADY: It has been reported that IVF culture media can deteriorate during storage, which suggests that the capacity of culture media to support optimal embryo development decreases over time. Some animal studies showed an effect of storage time on embryo development, in contrast to other studies, while the effect of aging culture medium on IVF outcome in humans is unknown. STUDY DESIGN, SIZE, DURATION: We used data on outcome of 1832 IVF/ICSI cycles with fresh embryo transfer, performed in the period 2008-2012 to evaluate the association of fertilization rate, embryonic development, ongoing pregnancy and birthweight of singletons with age of the culture medium (Vitrolife AB G-1 PLUS v5). PARTICIPANTS/MATERIALS, SETTING, METHODS: Age of the culture medium was calculated by subtracting the production date from the date of ovum retrieval. Data analysis included linear regression and logistic regression on continuous and categorical outcomes, respectively. MAIN RESULTS AND THE ROLE OF CHANCE: Age of the culture medium was not associated with fertilization rate (P = 0.543), early cleavage rate (P = 0.155), percentage of embryos containing four or more cells on Day 2 (P = 0.401), percentage of embryos containing eight or more cells on Day 3 (P = 0.175), percentage of embryos with multinucleated blastomeres (P = 0.527), or ongoing pregnancy (P = 0.729). However, birthweight of the newborn was inversely associated with age of the medium (ß = -3.6 g, SE: 1.5 g, P = 0.021), after controlling for possible confounders (day of embryo transfer, number of transferred embryos, child's gender, gestational age at birth, parity, pregnancy complications, maternal smoking, height and weight, and paternal height and weight) and the association was not biased by year of treatment, time since first opening of the bottle or batch variations. This indicates a difference of 234 g in birthweight of newborns for media with an age difference of 65 days. LIMITATIONS, REASONS FOR CAUTION: The results from this study may be specific for the G-1 PLUS v5 culture medium and extrapolation of the results to other media should be done with caution because of the differences in composition and shelf life. WIDER IMPLICATIONS OF THE FINDINGS: Age of G-1 PLUS v5 medium used to culture human embryos affects birthweight of the respective newborn. This could imply that the preimplantation embryo adapts to its in vitro environment with lasting in vivo consequences. Therefore, it is important that companies are transparent about the exact composition of their embryo culture media, which will allow IVF clinics to further investigate the effects of the media or media components on the health of IVF children. STUDY FUNDING/COMPETING INTERESTS: No funding and no competing interests declared. TRIAL REGISTRATION NUMBER: Not applicable.

Does the type of culture medium used influence birthweight of children born after IVF?

STUDY QUESTION: Do culture media influence birthweight of children born after IVF? SUMMARY ANSWER: Some studies have observed a significant effect of culture media on birthweight, while others have not, but since most studies compared different culture media, conventional meta-analysis was not possible. WHAT IS KNOWN ALREADY: Animal studies suggest that in vitro culture of embryos can have a significant effect on the birthweight of offspring when compared with in vivo developed embryos. The type of culture medium (or certain components of the medium) used is one of the causal factors. STUDY DESIGN, SIZE, DURATION: We reviewed all available literature reporting on a relation between culture medium and birthweight in human studies and a selection of animal studies. PARTICIPANTS/MATERIALS, SETTING, METHODS: An extensive literature search on Pubmed and Medline was performed with relevant search criteria relating to IVF, birthweight and culture medium. MAIN RESULTS AND THE ROLE OF CHANCE: Eleven studies reporting on a relationship between culture medium and birthweight in human were included in this review. Five of these found significant differences in birthweight when offspring born after culture in different culture media were compared. The remaining studies did not find differences in birthweight after changing culture medium. LIMITATIONS, REASONS FOR CAUTION: The number of human studies is limited and different culture media with different compositions are compared which makes a comparison between the studies difficult, if not impossible. Furthermore, most study designs were retrospective with consecutive use of different culture media and limited sample sizes, which makes bias of the results likely. WIDER IMPLICATIONS OF THE FINDINGS: If it could be confirmed that the type of culture medium used does indeed influence phenotypic characteristics (such as birthweight) of children born after IVF, it would underline the importance of monitoring the health of IVF children in relation to aspects of the laboratory techniques used during embryo culture. STUDY FUNDING/COMPETING INTERESTS: No funding was applicable to this study. No conflict of interest is declared.

Altered gene expression in human placentas after IVF/ICSI.

STUDY QUESTION: Is gene expression in placental tissue of IVF/ICSI patients altered when compared with a spontaneously conceived group, and are these alterations due to loss of imprinting (LOI) in the case of imprinted genes? SUMMARY ANSWER: An altered imprinted gene expression of H19 and Pleckstrin homology-like domain family A member 2 (PHLDA2), which was not due to LOI, was observed in human placentas after IVF/ICSI and several biological pathways were significantly overrepresented and mostly up-regulated. WHAT IS KNOWN ALREADY: Genomic imprinting plays an important role in placental biology and in placental adaptive responses triggered by external stimuli. Changes in placental development and function can have dramatic effects on the fetus and its ability to cope with the intrauterine environment. An increased frequency of placenta-related problems as well as an adverse perinatal outcome is seen in IVF/ICSI derived pregnancies, but the role of placental epigenetic deregulation is not clear yet. STUDY DESIGN AND PARTICIPANTS: In this prospective cohort study, a total of 115 IVF/ICSI and 138 control couples were included during pregnancy. After applying several exclusion criteria (i.e. preterm birth or stillbirth, no placental samples, pregnancy complications or birth defects), respectively, 81 and 105 placentas from IVF/ICSI and control pregnancies remained for analysis. Saliva samples were collected from both parents. METHODS: We quantitatively analysed the mRNA expression of several growth-related imprinted genes [H19, insulin-like growth factor 2 (IGF2), PHLDA2, cyclin-dependent kinase inhibitor 1C (CDKN1C), mesoderm-specific transcript homolog (MEST) isoform α and ß by quantitative PCR] after standardization against three housekeeping genes [Succinate dehydrogenase A (SDHA), YWHAZ and TATA-binding protein (TBP)]. A quantitative allele-specific expression analysis of the differentially expressed imprinted genes was performed to investigate LOI, independent of the mechanism of imprinting. Furthermore, a microarray analysis was carried out (n = 10 in each group) to investigate the expression of non-imprinted genes as well. MAIN RESULTS AND THE ROLE OF CHANCE: Both H19 and PHLDA2 showed a significant change, respectively, a 1.3-fold (P = 0.033) and 1.5-fold (P = 0.002) increase in mRNA expression in the IVF/ICSI versus control group. However, we found no indication that there is an increased frequency of LOI in IVF/ICSI placental samples. Genome-wide mRNA expression revealed 13 significantly overrepresented biological pathways involved in metabolism, immune response, transmembrane signalling and cell cycle control, which were mostly up-regulated in the IVF/ICSI placental samples. LIMITATIONS, REASONS FOR CAUTION: Only a subset of samples was found to be fully informative, which unavoidably led to lower sample numbers for our LOI analysis. Our study cannot distinguish whether the reported differences in the IVF/ICSI group are exclusively attributable to the IVF/ICSI technique itself or to the underlying subfertility of the patients. WIDER IMPLICATIONS OF THE FINDINGS: Whether these placental adaptations observed in pregnancies conceived by IVF/ICSI might be connected to an adverse perinatal outcome after IVF remains unknown. However, it is possible that these differences affect fetal development and long-term patterns of gene expression, as well as maternal gestational physiology. STUDY FUNDING/COMPETING INTERESTS: Partly funded by an unrestricted research grant by Organon BV (now MSD BV) and GROW School for Oncology and Developmental Biology without any role in study design, data collection and analysis or preparation of the manuscript. No conflict of interests to declare. TRIAL REGISTRATION NUMBER: Dutch Trial Registry (NTR) number 1298.

Impact of maternal cholesterol metabolism on ovarian follicle development and fertility.

The relationship among maternal lipid metabolism, fetal development, and adult disease of the offspring represents an emerging topic of high epidemiological relevance. The present review highlights the very early aspects of this process. Recent data suggest a link between lipid metabolism and reproduction/fertility, not only on the systemic level, but also locally on the level of the ovary that maintains its own sterol metabolism, likely in a self-regulated fashion. Follicular fluid - which surrounds oocytes in a developing follicle - contains all relevant lipoprotein subclasses that reach the follicular fluid either by diffusion, in the case of high-density lipoproteins (HDL), or by local production within the granulosa cells, in the case of very low-density lipoproteins (VLDL). Here, we summarize current knowledge on lipoprotein metabolism in the ovary in the context of fertility, and hypothesize that lipoproteins within follicular fluid are relevant to the development of the early embryo and thereby putatively also to the programming of metabolic disease later in life.