Pregnancy-related complications and perinatal outcomes resulting from transfer of cryopreserved versus fresh embryos in vitro fertilization: a meta-analysis.

OBJECTIVE: To provide an updated comparison of pregnancy-related complications and adverse perinatal outcomes of pregnancies conceived after frozen embryo transfer (FET) versus fresh embryo transfer (fresh ET). DESIGN: Meta-analysis. SETTING: University. PATIENT(S): Pregnancies resulting from FET versus fresh ET. INTERVENTIONS(S): Pubmed, Embase, Cochrane Library, Google Scholar, and Chinese databases, including the China National Knowledge Infrastructure Database, Wanfang, and Chinese Scientific Journals Full-Text Database were searched by two independent reviewers from January 1980 to September 2017. The results were expressed as risk ratios with 95% confidence intervals. MAIN OUTCOME MEASURE(S): Pregnancy-related complications and perinatal outcomes. RESULT(S): Our search retrieved 1,397 articles, of which 31 studies were included. Pregnancies resulting from FET were associated with lower relative risks of placenta previa, placental abruption, low birth weight, very low birth weight, very preterm birth, small for gestational age, and perinatal mortality compared with fresh ET. Pregnancies occurring from FET were associated with increased risks of pregnancy-induced hypertension, postpartum hemorrhage, and large for gestational age compared with fresh ET. The risks of gestational diabetes mellitus, preterm premature rupture of the membranes, and preterm birth (PTB) showed no differences between the two groups. CONCLUSION(S): Our analysis demonstrated that FET results in lower risks of placenta previa, placental abruption, low birth weight, very low birth weight, very preterm birth, small for gestational age, and perinatal mortality than fresh ET, some differences that are attributed to the increased risks of pregnancy-induced hypertension, large for gestational age, and postpartum hemorrhage. Although cryotechnology keeps improving, for comprehensive consideration, individual approaches remain appropriate to balance the options of FET or fresh ET at present.

Healthy offspring from freeze-dried mouse spermatozoa held on the International Space Station for 9 months.

If humans ever start to live permanently in space, assisted reproductive technology using preserved spermatozoa will be important for producing offspring; however, radiation on the International Space Station (ISS) is more than 100 times stronger than that on Earth, and irradiation causes DNA damage in cells and gametes. Here we examined the effect of space radiation on freeze-dried mouse spermatozoa held on the ISS for 9 mo at -95 °C, with launch and recovery at room temperature. DNA damage to the spermatozoa and male pronuclei was slightly increased, but the fertilization and birth rates were similar to those of controls. Next-generation sequencing showed only minor genomic differences between offspring derived from space-preserved spermatozoa and controls, and all offspring grew to adulthood and had normal fertility. Thus, we demonstrate that although space radiation can damage sperm DNA, it does not affect the production of viable offspring after at least 9 mo of storage on the ISS.

Abnormal implantation after fresh and frozen in vitro fertilization cycles.

OBJECTIVE: To determine whether fresh embryo transfers are at a higher risk of abnormal implantation compared with frozen embryo transfers while accounting for the embryo stage at transfer. DESIGN: Retrospective cohort study. SETTING: Not applicable. PATIENT(S): We used data from the Society for Assisted Reproductive Technologies to identify all fresh and frozen autologous IVF cycles from 2004-2013 resulting in a positive pregnancy test. The cycles were parameterized into a four-level predictor of [1] fresh blastocyst transfer, [2] fresh non-blastocyst transfer, [3] frozen blastocyst transfer, and [4] frozen non-blastocyst transfer. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): We examined a composite outcome of abnormal implantation, defined as biochemical pregnancy, ectopic/heterotopic pregnancy, and first-trimester pregnancy loss. Regression modeling was performed with repeated measures multivariable logistic regression, adjusted for age, parity, number of embryos transferred, infertility diagnosis, and calendar year of treatment. RESULT(S): Of 509,938 cycles analyzed, 31.8% resulted in abnormal implantation. Compared with a fresh blastocyst transfer, a fresh non-blastocyst transfer had a 22% increase risk of abnormal implantation, a frozen blastocyst transfer had a 36% increase risk, and a frozen non-blastocyst transfer had a 57% increase risk. When individual outcomes were analyzed, fresh embryo transfers had a lower risk of biochemical pregnancy and pregnancy loss but a higher risk for ectopic/heterotopic pregnancy. CONCLUSION(S): Fresh blastocyst transfers had the lowest overall risk of abnormal implantation but a higher risk of ectopic/heterotopic pregnancy. Although embryo cryopreservation is indicated in certain treatment cycles, elective embryo cryopreservation may not be the optimal strategy to adopt for all cycles.

Assessing the true incidence of mosaicism in preimplantation embryos.

Modern technologies applied to the field of preimplantation genetic diagnosis for aneuploidy screening (PGD-A) have improved the ability to identify the presence of mosaicism. Consequently, new questions can now be addressed regarding the potential impact of embryo mosaicism on diagnosis accuracy and the feasibility of considering mosaic embryos for transfer. The frequency of chromosomal mosaicism in products of conception (POCs) of early miscarriages has been reported to be low. Mosaic embryos with an aneuploid inner cell mass are typically lost during the first trimester owing to spontaneous miscarriages. Most of the mosaics in established pregnancies would derive from placental mosaicism or placental aneuploidy, and mosaic embryos with aneuploid inner cell mass should be lost mainly due to first-trimester spontaneous miscarriages. The well described clinical outcomes of live births from mosaic embryos suggest a wide spectrum of phenotypes, from healthy to severely impaired. Therefore, there is a need to balance the risks of discarding a possibly viable embryo with that of transferring an embryo that may ultimately have a lower implantation potential.

In vitro fertilization with preimplantation genetic diagnosis for aneuploidies in advanced maternal age: a randomized, controlled study.

OBJECTIVE: To determine the clinical value of preimplantation genetic diagnosis for aneuploidy screening (PGD-A) in women of advanced maternal age (AMA; between 38 and 41 years). DESIGN: This was a multicenter, randomized trial with two arms: a PGD-A group with blastocyst transfer, and a control group with blastocyst transfer without PGD-A. SETTING: Private reproductive centers. PATIENT(S): A total of 326 recruited patients fit the inclusion criteria, and 205 completed the study (100 in the PGD-A group and 105 in the control group). INTERVENTION(S): Day-3 embryo biopsy, array comparative genomic hybridization, blastocyst transfer, and vitrification. MAIN OUTCOME MEASURE(S): Primary outcomes were delivery and live birth rates in the first transfer and cumulative outcome rates. RESULT(S): The PGD-A group exhibited significantly fewer ETs (68.0% vs. 90.5% for control) and lower miscarriage rates (2.7% vs. 39.0% for control). Delivery rate after the first transfer attempt was significantly higher in the PGD-A group per transfer (52.9% vs 24.2%) and per patient (36.0% vs. 21.9%). No significant differences were observed in the cumulative delivery rates per patient 6 months after closing the study. However, the mean number of ETs needed per live birth was lower in the PGD-A group compared with the control group (1.8 vs. 3.7), as was the time to pregnancy (7.7 vs. 14.9 weeks). CONCLUSION(S): Preimplantation genetic diagnosis for aneuploidy screening is superior compared with controls not only in clinical outcome at the first ET but also in dramatically decreasing miscarriage rates and shortening the time to pregnancy.

Gestational carrier BMI and reproductive, fetal and neonatal outcomes: are the risks the same with increasing obesity?

OBJECTIVE: Data suggest that female obesity impairs uterine receptivity and increases the risk of fetal and neonatal mortality. We analyzed the reproductive outcomes of gestational carriers (GCs) undergoing donated oocytes and assisted reproductive technology according to body mass index (BMI). DESIGN: A retrospective analysis of 163 GCs undergoing 226 in vitro fertilization (IVF) and embryo transfer cycles. METHODS: GCs undergoing in vitro fertilization and embryo transfer cycles were analyzed and divided according to their BMI (healthy weight: 20-24.9 kg m(-2) (n=77 in 114 cycles); overweight: 25-29.9 kg m(-)(2) (n=55 in 71 cycles); and obese: 30-35 kg m(-)(2) (n=31 in 41 cycles)). All GCs underwent a complete medical evaluation and were cleared for pregnancy before being selected. Overweight and obese GCs also underwent a metabolic screening, including an oral glucose tolerance test and lipid profile. The main outcomes measured were clinical pregnancy and live birth rates, antenatal and neonatal outcomes. RESULTS: Clinical pregnancy and live birth rates were similar despite increasing BMI. There were no statistically significant differences in the implantation rates, clinical pregnancy rates or live birth rates per embryo transfer among patients in the three BMI groups. In the healthy weight, overweight and obese GCs, the clinical pregnancy rates per GC were 72%, 84% and 79%, and per embryo transfer rates were 52%, 49% and 56%, respectively; P=NS. The live birth rates per GC were 70%, 84% and 75%, and per embryo transfer rates were 50%, 49% and 53%, respectively; P=NS. Twin rates were similar between the groups (35%, 31% and 29%, respectively; P=NS). There were no differences in gestational diabetes, preterm admissions or cesarean section rates. Neonatal intensive care unit admissions were similar (11%, 13% and 12%, respectively; P=NS), and no maternal, neonatal or infant mortality occurred. CONCLUSIONS: These data show that increasing obesity does not impair the reproductive outcome in GC cycles. Larger sample size is indicated to verify these findings. Furthermore, this study suggests that the standard metabolic screening used for GCs may lead to selection of healthier patients compared with women of comparable BMI who conceive outside of a fertility clinic setting, indicating the metabolic profile, rather than BMI, may better explain differences in pregnancy outcomes.

Superovulatory response to gonadotrophin FSH/LH treatment and effect of progestin supplement to recipients on survival of transferred vitrified embryos in goats.

Two experiments were carried out in goats to evaluate the effects of the FSH/LH ratio during treatment on ovarian response and embryo production (experiment 1) and the efficiency of progestin supplementation on pregnancy and the survival of vitrified embryos (experiment 2). In experiment 1, 30 goats were synchronized and allocated to 2 groups (n = 15) corresponding to the following superovulatory treatments with p-FSH (250 IU, over 3 days) having different doses of purified FSH and LH: (group A) control, FSH/LH ratio of 1, kept constant during treatment; (group B) FSH/LH ratio of 2 and daily FSH/LH ratio of 5.0:1.0:0.3 for the first, second, and third days of treatment, respectively. Ovarian response and embryo production were assessed 7.5 days after estrus. In experiment 2, 46 vitrified blastocysts from p-FSH-superovulated donors were transferred to 26 recipients (2 blastocysts per goat) 7.5 days after estrus. The recipients were synchronized with donors and allocated to 2 experimental groups (n = 13). Group C received progestin supplement as fluorgestone acetate (FGA) inserted into the vagina at the time of embryo transfer, replaced with a new one 16 days later, and maintained until the 45th day of pregnancy; group D, no treatment (control). Pregnancy was diagnosed by transrectal ultrasound scanning on Days 30 and 45 after estrus and followed to term. The results indicated that the increase in FSH/LH ratio from 1 to 2 with decreasing daily FSH/LH (treatment B) did not improve the superovulatory response. Superovulatory treatment A (control) advanced (P < 0.05) the onset of estrus and showed a higher ovulation rate compared to group B (14.9 vs. 10.9; P < 0.05). Fertilization rate, embryo yield, and mean number of transferable embryos in group A (7.5) were higher (P < 0.05) than those in group B (3.2). Recipient goats receiving progestin supplementation (group C) showed a higher (P < 0.05) pregnancy rate and embryo survival (kids born per embryos transferred; 69.3% and 73.1%) than the controls (group D; 23.3% and 19.2%). In conclusion, regimen A with FSH/LH ratio of 1 kept constant during the treatment gave the best ovarian response and embryo production. The progestin supplementation as FGA-pessary administered at embryo transfer time to the 45th day of pregnancy improved the pregnancy rate, kidding rate, and embryo survival of transferred vitrified embryos. Intravaginal progestin supplement has the potential to reduce the incidence of pregnancy losses during early pregnancy.

Comparison of live-birth defects after luteal-phase ovarian stimulation vs. conventional ovarian stimulation for in vitro fertilization and vitrified embryo transfer cycles.

OBJECTIVE: To assess live-birth defects after a luteal-phase ovarian-stimulation regimen (LPS) for in vitro fertilization (IVF) and vitrified embryo transfer (ET) cycles. DESIGN: Retrospective cohort study. SETTING: Tertiary-care academic medical center. PATIENT(S): Infants who were born between January 1, 2013 and May 1, 2014 from IVF with intracytoplasmic sperm injection (ICSI) treatments (n = 2,060) after either LPS (n = 587), the standard gonadotropin-releasing hormone-agonist (GnRH-a) short protocol (n = 1,257), or mild ovarian stimulation (n = 216). INTERVENTION(S): The three ovarian-stimulation protocols described and assisted reproductive technology (ART) treatment (IVF or ICSI, and vitrified ET) in ordinary practice. MAIN OUTCOME MEASURE(S): The main measures were: gestational age, birth weight and length, multiple delivery, early neonatal mortality, and birth defects. Associations were assessed using logistic regression by adjusting for confounding factors. RESULT(S): The final sample included 2,060 live-born infants, corresponding to 1,622 frozen-thawed (FET) cycles, which led to: 587 live-born infants from LPS (458 FET cycles); 1,257 live-born infants from the short protocol (984 FET cycles); and 216 live-born infants from mild ovarian stimulation (180 FET cycles). Birth characteristics regarding gestational age, birth weight and length, multiple delivery, and early neonatal death were comparable in all groups. The incidence of live-birth defects among the LPS group (1.02%) and the short GnRH-a protocol group (0.64%) was slightly higher than in the mild ovarian-stimulation group (0.46%). However, none of these differences reached statistical significance. For congenital malformations, the risk significantly increased for the infertility-duration factor and multiple births; the adjusted odds ratios were 1.161 (95% confidence interval [CI]: 1.009-1.335) and 3.899 (95% CI: 1.179-12.896), respectively. No associations were found between congenital birth defects and various ovarian-stimulation regimens, maternal age, body mass index, parity, insemination method, or infant gender. CONCLUSION(S): To date, the data do not indicate an elevated rate of abnormality at birth after LPS, but further study with larger populations is needed to confirm these results. However, infertility itself poses a risk factor for congenital malformation. A higher likelihood of birth defects in multiple births may lead couples to favor elective, single ET; couples undertaking ART should be made aware of the known increased birth defects associated with a twin birth.

Obstetric and perinatal outcomes in singleton pregnancies resulting from the transfer of blastocyst-stage versus cleavage-stage embryos generated through in vitro fertilization treatment: a systematic review and meta-analysis.

OBJECTIVE: To perform a systematic review and meta-analysis of obstetric and perinatal complications in singleton pregnancies after the transfer of blastocyst-stage and cleavage-stage embryos generated through IVF. DESIGN: Systematic review. SETTING: University hospital. PATIENT(S): Singleton pregnancies resulting from ET at the blastocyst stage versus those at the cleavage stage. INTERVENTION(S): Medline, EMBASE, Cochrane Central Register of Clinical Trials DARE, and CINAHL (1980-2013) were searched. Two independent reviewers extracted data and assessed the methodological quality of the relevant studies using CASP scoring. Risk ratios and risk differences were calculated in Rev Man 5.1. MAIN OUTCOME MEASURE(S): Very preterm birth, preterm birth, small for gestational age, low birth weight, very low birth weight, congenital anomalies, perinatal mortality, preeclampsia, and placenta previa. RESULT(S): In vitro fertilization pregnancies occurring as a result of ET at the blastocyst stage were associated with a higher relative risk (RR; 95% confidence interval [CI]) of preterm (RR 1.27; 95% CI 1.22-1.31) and very preterm delivery (RR 1.22; 95% CI 1.10-1.35) in comparison with those resulting from the transfer of cleavage-stage embryos. The risk of growth restriction was lower in babies conceived through blastocyst transfer (RR 0.82; 95% CI 0.77-0.88). CONCLUSION(S): Data from observational studies show that ET at the blastocyst stage is associated with a higher risk of very preterm delivery. However, we were not able to adjust for confounders. Perinatal outcome data from existing randomized trials are needed to determine the safety of ET at the blastocyst stage compared with the cleavage stage.

Perinatal mortality following assisted reproductive technology treatment in Australia and New Zealand, a public health approach for international reporting of perinatal mortality.

BACKGROUND: There is a need to have uniformed reporting of perinatal mortality for births following assisted reproductive technology (ART) treatment to enable international comparison and benchmarking of ART practice. METHODS: The Australian and New Zealand Assisted Reproduction Database was used in this study. Births of ≥ 20 weeks gestation and/or ≥ 400 grams of birth weight following embryos transfer cycles in Australia and New Zealand during the period 2004 to 2008 were included. Differences in the mortality rates by different perinatal periods from a gestational age cutoff of ≥ 20, ≥ 22, ≥ 24, or ≥ 28 weeks (wks) to a neonatal period cutoff of either < 7 or < 28 days after birth were assessed. Crude and specific (number of embryos transferred and plurality) rates of perinatal mortality were calculated for selected gestational and neonatal periods. RESULTS: When the perinatal period is defined as ≥ 20 wks gestation to < 28 days after birth, the perinatal mortality rate (PMR) was 16.1 per 1000 births (n = 630). A progressive contraction of the gestational age groups resulted in marked reductions in the PMR for deaths at < 28 days (22 wks 11.0; 24 wks 7.7; 28 wks 5.6); and similarly for deaths at < 7 days (20 wks 15.6, 22 wks 10.5; 24 wks 7.3; 28 wks 5.3). In contrast, a contraction of the perinatal period from < 28 to < 7 days after birth only marginally reduced the PMR from 16.2 to 15.6 per 1000 births which was consistent across all gestational ages.The PMR for single embryo transfer (SET) births (≥ 20 weeks gestation to < 7 days post-birth) was significantly lower (12.8 per 1000 SET births) compared to double embryo transfer (DET) births (PMR 18.3 per 1000 DET births; p < 0.001, Fisher's Exact Test). Similarly, the PMR for SET births (≥ 22 weeks gestation to < 7 days post-birth) was significantly lower (8.8 per 1000 SET births, p < 0.001, Fisher's Exact Test) when compared to DET births (12.2 per 1000 DET births). The highest PMR (50.5 per 1000 SET births, 95% CI 36.5-64.5) was for twins following SET births (≥ 20 weeks gestation to < 7 days post-birth) compared to twins following DET (23.9 per 1000 DET births, 95% CI 20.8-27.1). CONCLUSION: Reporting of perinatal mortality of ART births is an essential component of quality ART practice. This should include measures that monitor the impact on perinatal mortality of multiple embryo transfer. We recommend that reporting of perinatal deaths following ART treatment, should be stratified for three gestation-specific perinatal periods of ≥ 20, ≥ 22 and ≥ 28 completed weeks to < 7 days post-birth; and include plurality specific rates by SET and DET. This would provide a valuable international evidence-base of PMR for use in evaluating ART policy, practice and new research.

Correlação entre os métodos de concepção, ocorrência e formas de tratamento das onfalopatias em bovinos: estudo retrospectivo / Correlation between conception methods, occurrence, and type o treatment of the umbilical diseases in cattle: a retrospective study

Alguns problemas têm sido observados nos bezerros produtos da técnica fertilização in vitro, dentre esses a elevada casuística de onfalopatias. A partir dessa observação, objetivou-se com este trabalho realizar um estudo retrospectivo da correlação entre os métodos de concepção e a ocorrência de onfalopatias em bovinos e descrever os resultados obtidos a partir dos tratamentos conservativo e cirúrgico. Foram utilizados 44 bovinos atendidos no Hospital Veterinário da Unesp, Campus de Araçatuba, com idade variando de um dia a 12 meses entre os anos de 2003 e 2007. Desses bovinos 27 eram provenientes de fertilização in vitro (FIV), 12 de inseminação artificial (IA), dois de monta natural (MN) e três de transferência de embriões (TE). O diagnóstico clínico-cirúrgico revelou que todos apresentavam afecções umbilicais, sendo 22 casos de persistência de úraco, oito de onfaloflebite, oito de hérnias umbilicais, cinco de onfalites e um de fibrose umbilical. Inicialmente e no pós-operatório administrou-se em todos os animais, uma vez ao dia, durante dez dias, 3mg/kg de ceftiofur sódico pela via intravenosa (IV). Nos casos de infecção grave ou irresponsiva a terapia antimicrobiana inicial, acrescentou-se 6,6mg/kg, durante sete dias de sulfato de gentamicina IV. A antissepsia do umbigo, com tintura de iodo a 2 por cento, foi instituída duas vezes ao dia, nos casos tratados conservativamente, enquanto que os bovinos submetidos à cirurgia receberam 1,1mg/kg de flunixin meglumine IV, uma vez ao dia, por cinco dias consecutivos. Dos 22 animais diagnosticados com persistência de úraco, 10 apresentavam drenagem de urina pelo umbigo e receberam 2mL de tintura de iodo 10 por cento no interior do úraco, sendo 15 tratados com a excisão cirúrgica, especialmente, devido à formação de divertículo vésico-uracal. Todos os animais que apresentavam onfaloflebite e hérnia umbilical foram submetidos à cirurgia...

Some problems have been observed in bovine products of the in vitro fertilization technical, among these, the high umbilical diseases casuistry. From this observation, the aim of this work was to accomplish a retrospective study of the correlation between the conception methods and the occurrence of umbilical diseases in bovines and describe the results obtained from the conservative and surgical treatments. For this 44 animals attended at Veterinary Teaching Hospital of Unesp Araçatuba, with age varying from one day to 12 months among the years of 2003 and 2007 were used, twenty seven were from in vitro fertilization (IVF), twelve were from artificial insemination (AI), two were from natural mounts and three were from embryo transfer. The clinical-surgical diagnosis of the animals revealed that all of them presented umbilical disorders, being 22 cases of urachus patent, eight omphalophlebitis, eight umbilical hernia, five omphalitis and one umbilical fibrosis. Before and at the postoperative period was administered in all animals once a day for ten days 3mg/kg of ceftiofur sodium IV. In cases of serious infection or lack of response of the initial antimicrobial therapy a complementary treatment during seven days with 6.6 mg/kg of gentamicin sulfate IV was carried out. The antisepsis of the umbilicus with tincture of iodine to 2 percent was carried out twice daily in cases treated clinically, with out surgery, while the animals underwent surgery received 1.1mg/kg of flunixin meglumine IV once daily for five consecutive days.Among the 22 animals diagnosed with urachus patent, 10 had urine drainage from the umbilicus and received 2mL of 10 percent tincture of iodine in the urachus, and 15 was treated with surgical excision, due to formation of diverticulum from the blader to urachus. All animals that were affected with omphalophlebitis and umbilical hernia were submitted to surgery...

Chemokine scavenger D6 is expressed by trophoblasts and aids the survival of mouse embryos transferred into allogeneic recipients.

Proinflammatory CC chemokines are thought to drive recruitment of maternal leukocytes into gestational tissues and regulate extravillous trophoblast migration. The atypical chemokine receptor D6 binds many of these chemokines and is highly expressed by the human placenta. D6 is thought to act as a chemokine scavenger because, when ectopically expressed in cell lines in vitro, it efficiently internalizes proinflammatory CC chemokines and targets them for destruction in the absence of detectable chemokine-induced signaling. Moreover, D6 suppresses inflammation in many mouse tissues, and notably, D6-deficient fetuses in D6-deficient female mice show increased susceptibility to inflammation-driven resorption. In this paper, we report strong anti-D6 immunoreactivity, with specific intracellular distribution patterns, in trophoblast-derived cells in human placenta, decidua, and gestational membranes throughout pregnancy and in trophoblast disease states of hydatidiform mole and choriocarcinoma. We show, for the first time, that endogenous D6 in a human choriocarcinoma-derived cell line can mediate progressive chemokine scavenging and that the D6 ligand CCL2 can specifically associate with human syncytiotrophoblasts in term placenta in situ. Moreover, despite strong chemokine production by gestational tissues, levels of D6-binding chemokines in maternal plasma decrease during pregnancy, even in women with pre-eclampsia, a disease associated with increased maternal inflammation. In mice, D6 is not required for syngeneic or semiallogeneic fetal survival in unchallenged mice, but interestingly, it does suppress fetal resorption after embryo transfer into fully allogeneic recipients. These data support the view that trophoblast D6 scavenges maternal chemokines at the fetomaternal interface and that, in some circumstances, this can help to ensure fetal survival.

An evaluation of embryo, zygote and oocyte cryopreservation in assisted reproductive technology.

The study compared (i) the outcome between cryopreserved ICSI fertilized embryo and cryopreserved ICSI fertilized pronuclear stage zygotes and (ii) the outcome between cryopreserved fertilized mature oocytes with cryopreserved immature oocytes, fertilized by ICSI following thawing. Comparative retrospective review of relevant studies satisfying study criteria. Studies were identified through MEDLINE literature search. Study outcomes were cryosurvival, fertilization, implantation, pregnancy, and delivery rates. Pronucleate zygotes had better cryosurvival rates than the cleaving embryo (90.7% versus 59.9%) and almost double the clinical pregnancy rates for cleaving embryo (12.8% versus 7.0%). There was an almost three-fold higher delivery rate for the pronucleate zygote compared with cleaving embryo (11.6% versus 4.3%). Immature oocytes had lower cryosurvival rates than mature oocytes (34.5% versus 52.3%). Mature and immature oocytes showed good fertilization rates (59.3% versus 50%) and satisfactory embryonic development (90.3% versus 100.0%). Immature oocytes had higher delivery rate per embryo transferred than the mature oocyte (40.0% versus 2.7%). Pronucleate zygote cryopreservation has an advantage over the cleaving embryo. The low survival rate following thawing is still an obstacle to the integration of oocyte cryopreservation into ART.

Potential factors affecting embryo survival and clinical outcome with cryopreserved pronuclear human embryos.

OBJECTIVE: This study was undertaken to determine whether the method of fertilization has a significant impact on survival and/or clinical pregnancy rates of cryopreserved human pronuclear (2PN) stage embryos. DESIGN: A retrospective analysis of cryosurvival and clinical pregnancy rates after thawing of 2PN stage embryos from January 2000 through December 2002 in a private Assisted Reproductive Technology (ART) center. MATERIAL AND METHODS: A total of 1408 human 2PN embryos were cryopreserved using a Planer Kryo 10 Series III freezing unit (TS Scientific, Perkasie, Pa) after dehydration/equilibration through Propanediol (Sigma Chemical, St. Louis, Mo) and sucrose. On thawing, embryos were cultured in vitro with P-1 medium with 10% Serum Substitute Supplement (Irvine Scientific, Santa Ana, Calif). Embryo transfer was performed at 40 to 48 hours from time of thaw into a recipient uterus after standard estradiol/progesterone preparation. RESULTS: In 2000, 78% of all frozen 2PN embryos survived and were transferred in 181 cycles producing a delivery rate of 26% per transfer. However, 59% of these cycles were intracytoplasmic sperm injection (ICSI), and the survival of frozen 2PN from these cycles (72%) was lower than the respective survival of frozen 2PN embryos from in vitro fertilization (IVF) (81%; P<.025). Changes to protocols for thawing frozen 2PN embryos were therefore explored and implemented during 2001, resulting in equivalent survival rates of frozen 2PN embryos from IVF and ICSI during 2001 (78% and 80%, respectively) and 2002 (73% and 74%, respectively). Coincidentally, the proportion of all cycles that were performed with ICSI increased (73% in 2001 to 78% in 2002; P<.01) and pregnancy rates after transfer of frozen/thawed 2PN embryos from ICSI increased from 15% in 2000 to 30% in 2002. CONCLUSION: 2PN stage embryo cryosurvival may be negatively affected by ICSI, possibly caused by disruption of the zona pellucida and vitelline membrane before cryopreservation, and/or because ICSI promotes fertilization of some compromised eggs (producing compromised 2PN embryos) that would not have fertilized by conventional IVF. Without close attention to embryo freezing and thawing protocols relative to outcome, lower cryosurvival of unselected ICSI-produced embryos can negatively impact pregnancy outcomes.

Monozygotic twinning associated with day 5 embryo transfer in pregnancies conceived after IVF.

BACKGROUND: This study examines the association between day of embryo transfer and monozygotic (MZ) twinning. METHODS: We used a population-based sample of 108,36 IVF/embryo transfer procedures in which the patients oocytes' were freshly fertilized (non-frozen; non-donor) and 39,98 resultant pregnancies from US clinics in 1999 and 2000. Cases were pregnancies for which the number of fetal hearts observed on ultrasound exceeded the number of embryos transferred. These pregnancies were considered to contain at least one set of MZ twins. A total of 226 MZ pregnancies were compared with two control groups: 23,880 singleton pregnancies (one fetal heart) and 15,092 other multiple-gestation pregnancies (> or = 2 fetal hearts but the number of fetal hearts on ultrasound was less than or equal to the number of embryos transferred). RESULTS: Cases of presumed MZ multiple-gestation pregnancies were more likely to have had a day 5 embryo transfer compared with day 3 embryo transfers than singleton pregnancies [adjusted odds ratio (AOR) = 3.92, 95% confidence interval (CI) = 2.97-5.17] or other multiple-gestation pregnancies (AOR = 3.91, 95% CI = 2.96-5.17) conceived with IVF/embryo transfer. CONCLUSIONS: Day 5 embryo transfer may be associated with increased MZ twinning.

A new method for cryopreservation of mouse spermatozoa.

A new method for the cryopreservation of mouse spermatozoa was developed using a modified egg-yolk TES-Tris diluent containing 0.1% sodium lauryl sulfate and 1.25% (v/v) glycerol (mouse sperm cryoprotectant, MSC). Epididymal spermatozoa collected from 10-week-old CBA males were frozen at a rate of 5 degrees C min-1 to 4 degrees C and 50 degrees C min-1 to -70 degrees C using a programmable cell freezer. A percentage of the spermatozoa (25%) regained motility after thawing. In vitro fertilization with frozen-thawed spermatozoa resulted in 50% of oocytes developing to the two-cell stage. These two-cell embryos were placed in the oviducts of pseudopregnant recipients (C57BL/CBA) and 16% developed to be viable fetuses, or in the oviducts of pregnant recipients (MF1) and 17% developed to live offspring.