Associations of IVF singleton birthweight and gestation with clinical treatment and laboratory factors: a multicentre cohort study.

STUDY QUESTION: Do IVF treatment and laboratory factors affect singleton birthweight (BW)? SUMMARY ANSWER: BWs of IVF-conceived singleton babies are increasing with time, but we cannot identify the specific treatment factors responsible. WHAT IS KNOWN ALREADY: IVF-conceived singleton babies from fresh transfers have slightly lower BW than those conceived naturally, whilst those from frozen embryo transfer (FET) cycles are heavier and comparable to naturally conceived offspring. Our recent studies have shown that BW varies significantly between different IVF centres, and in a single centre, is also increasing with time, without a corresponding change in BWs of naturally conceived infants. Although it is likely that factors in the IVF treatment cycle, such as hormonal stimulation or embryo laboratory culture conditions, are associated with BW differences, our previous study designs were not able to confirm this. STUDY DESIGN, SIZE, DURATION: Data relating to BW outcomes, IVF treatment and laboratory parameters were collated from pre-existing electronic records in five participating centres for all singleton babies conceived between August 2007 and December 2014. PARTICIPANTS/MATERIALS, SETTING, METHODS: Seven thousand, five hundred and eighty-eight births, 6207 from fresh and 1381 from FET. Infants with severe congenital abnormalities were excluded. The primary outcome of gestation-adjusted BW and secondary outcomes of unadjusted BW and gestation were analysed using multivariable regression models with robust standard errors to allow for the correlation between infants with the same mother. The models tested treatment factors allowing for confounding by centre, time and patient characteristics. A similar matched analysis of a subgroup of 379 sibling pairs was also performed. MAIN RESULTS AND THE ROLE OF CHANCE: No significant associations of birth outcomes with IVF embryo culture parameters were seen independent of clinic or time, including embryo culture medium, incubator type or oxygen level, although small differences cannot be ruled out. We did not detect any significant differences associated with hormonal stimulation in fresh cycles or hormonal synchronization in FET cycles. Gestation-adjusted BW increased by 13.4 (95% CI 0.6-26.1) g per year over the period of the study, and babies born following FET were 92 (95% CI 57-128) g heavier on average than those from the fresh transfer. LIMITATIONS, REASONS FOR CAUTION: Although no specific relationships have been identified independent of clinic and time, the confidence intervals remain large and do not exclude clinically relevant effect sizes. As this is an observational study, residual confounding may still be present. WIDER IMPLICATIONS OF THE FINDINGS: This study demonstrates the potential for large scale analysis of routine data to address critical questions concerning the long-term implications of IVF treatment, in accordance with the Developmental Origins of Health and Disease hypothesis. However, much larger studies, at a national scale with sufficiently detailed data, are required to identify the treatment parameters associated with differences in BW or other relevant outcomes. STUDY FUNDING/COMPETING INTEREST(S): This work was supported by the EU FP7 project grant, EpiHealthNet (FP7-PEOPLE-2012-ITN-317146). No competing interests were identified. TRIAL REGISTRATION NUMBER: N/A.

The impact of IVF on birthweight from 1991 to 2015: a cross-sectional study.

STUDY QUESTION: Has birthweight (BW) changed over time among IVF-conceived singletons? SUMMARY ANSWER: Singleton BW has increased markedly over the past 25 years. WHAT IS KNOWN ALREADY: IVF conceived singletons have had a higher incidence of low BW compared to spontaneously conceived singletons, and this has raised concerns over long-term increased risks of cardio-metabolic disease. However, few causal links between IVF procedures and BW have been robustly established, and few studies have examined whether BW has changed over time as IVF techniques have developed. STUDY DESIGN, SIZE, DURATION: A total of 2780 live born singletons conceived via IVF or ICSI treated in the reproductive medicine department of a single publicly funded tertiary care centre between 1991 and 2015 were included in this retrospective study. The primary outcome measure was singleton BW adjusted for gestational age, maternal parity and child gender. Multivariable linear regression models were used to estimate the associations between patient prognostic factors and IVF treatment procedures with adjusted BW. PARTICIPANTS/MATERIALS, SETTING, METHODS: All singletons conceived at the centre following IVF/ICSI using the mother's own oocytes, and non-donated fresh or frozen/thawed embryos with complete electronic data records, were investigated. Available electronic records were retrieved from the Human Fertilization and Embryology Authority for dataset collation. Multiple linear regression analysis was used to evaluate associations between IVF treatment parameters and BW, after adjusting for the year of treatment and patient characteristics and pregnancy factors. MAIN RESULTS AND THE ROLE OF CHANCE: In the primary multivariable model, singleton BW increased by 7.4 g per year (95% CI: 3.2-11.6 g, P = 0.001), an increase of close to 180 g throughout the 25-year period after accounting for gestational age, maternal parity, child gender, IVF treatment parameters, patient prognostic characteristics and pregnancy factors. Fresh and frozen embryo transfer-conceived singletons showed a similar increase in BW. Frozen/thawed embryo transfer conceived singletons were on average 53 g heavier than their fresh embryo conceived counterparts (95% CI: 3.7-103.3 g, P = 0.035). LIMITATIONS, REASONS FOR CAUTION: The independent variables included in the study were limited to those that have been consistently recorded and stored electronically over the past two decades. WIDER IMPLICATIONS OF THE FINDINGS: There has been a progressive BW increase in IVF singletons over time in one large centre with consistent treatment eligibility criteria. Such a change is not seen in the general population of live born singletons in the UK or other developed countries, and seems to be specific to this IVF population. This may be a reflection of changes in practice such as undisturbed extended embryo culture to the blastocyst stage, optimized commercial culture media composition, single embryo transfer and ICSI. Moreover, singletons conceived from frozen/thawed embryos had higher birth weights when compared to their fresh embryo transfer counterparts. The causal pathway is unknown; however, it could be due to the impact on embryos of the freeze/thaw process, self-selection of embryos from couples who produce a surplus of embryos, and/or embryo replacement into a more receptive maternal environment. STUDY FUNDING/COMPETING INTEREST(S): This work was supported by the EU FP7 project grant, EpiHealthNet (FP7-PEOPLE-2012-ITN-317146). The authors have no competing interests to declare. TRIAL REGISTRATION NUMBER: N/A.

Comparative Effectiveness of Umeclidinium/Vilanterol versus Inhaled Corticosteroid/Long-Acting ß2-Agonist in Patients with Chronic Obstructive Pulmonary Disease in a Primary Care Setting in England.

Purpose: To compare adherence to once-daily umeclidinium/vilanterol (UMEC/VI), a long-acting muscarinic antagonist/long-acting ß2-agonist (LAMA/LABA), and twice-daily inhaled corticosteroids (ICS)/LABA single-inhaler dual therapy in patients with chronic obstructive pulmonary disease (COPD) in a primary care cohort in England. Patients and Methods: Active comparator, new-user, retrospective cohort study using CPRD-Aurum primary care data and linked Hospital Episode Statistics secondary care administrative data. Patients without exacerbations in the previous year were indexed on first/earliest prescription date of once-daily UMEC/VI or twice-daily ICS/LABA as initial maintenance therapy between July 2014-September 2019. Primary outcome: medication adherence at 12 months post-index, defined as proportion of days covered (PDC) ≥80%. PDC represented proportion of time over the treatment duration that the patient was theoretically in possession of the medication. Secondary outcomes: adherence at 6, 18, and 24 months post-index, time-to-triple therapy, time-to-first on-treatment COPD exacerbation, COPD-related and all-cause healthcare resource utilization (HCRU), and direct health-care costs. A propensity score was generated and inverse probability of treatment weighting (IPTW) was used to balance potential confounders. Superiority was defined as >0% difference between treatment groups. Results: In total, 6815 eligible patients were included (UMEC/VI:1623; ICS/LABA:5192). At 12 months post-index, weighted odds of a patient being adherent were significantly greater with UMEC/VI versus ICS/LABA (odds ratio [95% CI]: 1.71 [1.09, 2.66]; p=0.0185), demonstrating superiority of UMEC/VI. Patients taking UMEC/VI were statistically significantly more adherent than those taking ICS/LABA at 6, 18, and 24 months post-index (p<0.05). Differences in time-to-triple therapy, time-to-moderate COPD exacerbations, HCRU, and direct medical costs were not statistically significant between treatments after IPTW was applied. Conclusion: At 12 months post-treatment initiation, once-daily UMEC/VI was superior to twice-daily ICS/LABA in medication adherence among patients with COPD without exacerbations in the previous year, newly initiating dual maintenance therapy in England. The finding was consistent at 6, 18, and 24 months.

Comparison of Rescue Medication Prescriptions in Patients with Chronic Obstructive Pulmonary Disease Receiving Umeclidinium/Vilanterol versus Tiotropium Bromide/Olodaterol in Routine Clinical Practice in England.

Purpose: Routinely collected healthcare data on the comparative effectiveness of the long-acting muscarinic antagonist/long-acting ß2-agonist combination umeclidinium/vilanterol (UMEC/VI) versus tiotropium bromide/olodaterol (TIO/OLO) for chronic obstructive pulmonary disease (COPD) is limited. This study compared rescue medication prescriptions in patients with COPD in England receiving UMEC/VI versus TIO/OLO. Patients and Methods: This retrospective cohort study used primary care data from the Clinical Practice Research Datalink Aurum database linked with secondary care administrative data from Hospital Episode Statistics. Patients with a COPD diagnosis at age ≥35 years were included (indexed) following initiation of single-inhaler UMEC/VI or TIO/OLO between July 1, 2015, and September 30, 2019. Outcomes included the number of rescue medication prescriptions at 12-months (primary), and at 6-, 18- and 24-months (secondary), adherence at 6-, 12-, 18- and 24-months post-index, defined as proportion of days covered ≥80% (secondary), and time-to-initiation of triple therapy (exploratory). Inverse probability of treatment weighting (IPTW) was used to balance potential confounding baseline characteristics. Superiority of UMEC/VI versus TIO/OLO for the primary outcome of rescue medication prescriptions was assessed using an intention-to-treat analysis with a p-value < 0.05. Results: In total, 8603 patients were eligible (UMEC/VI: n = 6536; TIO/OLO: n = 2067). Following IPTW, covariates were well balanced across groups. Patients initiating UMEC/VI had statistically significantly fewer (mean [standard deviation]; p-value) rescue medication prescriptions versus TIO/OLO in both the unweighted (4.84 [4.78] vs 5.68 [5.00]; p < 0.001) and weighted comparison (4.91 [4.81] vs 5.48 [5.02]; p = 0.0032) at 12 months; consistent results were seen at all timepoints. Adherence was numerically higher for TIO/OLO versus UMEC/VI at all timepoints. Time-to-triple therapy was similar between treatment groups. Conclusion: UMEC/VI was superior to TIO/OLO in reducing rescue medication prescriptions at 12 months after treatment initiation in a primary care cohort in England, potentially suggesting improvements in symptom control with UMEC/VI compared with TIO/OLO.

The impact of selected embryo culture conditions on ART treatment cycle outcomes: a UK national study.

STUDY QUESTION: Are selected embryo culture conditions namely media, oxygen level, and incubator type, associated with IVF live birth rate (LBR) and the health of singleton offspring at birth? SUMMARY ANSWER: There were statistically significant differences in LBR between the eight culture media systems analysed; however, none of the embryo culture factors showed statistically significant associations with birth weight (BW) in multivariable regression analyses. WHAT IS KNOWN ALREADY: In clinical ART culture media is the initial environment provided for the growth of human embryos. Pre-implantation development is a critical period of developmental plasticity, which could have long-lasting effects on offspring growth and health. Although some studies have shown an impact of culture medium type on BW, the interaction between culture medium type and associated culture conditions on both treatment success rates (LBR) and offspring BW is largely unexplored. This study aimed to examine these factors in a large multicentre national survey capturing the range of clinical practice. STUDY DESIGN SIZE DURATION: In this cross-sectional study, data from a survey circulated to all UK IVF clinics requesting information regarding culture medium type, incubator type, and oxygen level used in ART between January 2011 and December 2013 were merged with routinely recorded treatment and outcome data held in the Human Fertilisation and Embryology Authority Register up to the end of 2014. PARTICIPANTS/MATERIALS SETTING METHODS: Forty-six (62%) UK clinics responded to the survey. A total of 75 287 fresh IVF/ICSI cycles were captured, including 18 693 singleton live births. IVF success (live birth, singleton or multiple; LB), singleton gestation and singleton gestation-adjusted BW were analysed using logistic and linear regression models adjusting for patient/treatment characteristics and clinic-specific effects. MAIN RESULTS AND THE ROLE OF CHANCE: Culture medium type was shown to have some impact on LBR (multivariable logistic regression, (MRL); post-regression Wald test, P < 0.001), but not on BW (MLR; post-regression Wald test, P = 0.215). However, blastocyst culture had the largest observed effect on odds of LBR (odds ratio (OR) = 1.35, CI: 1.29-1.42), increased the risk of pre-term birth even when controlling for oxygen tension (MLR; OR = 1.42, CI: 1.23-1.63), and gestation-adjusted BW (MLR, ß = 38.97 g, CI: 19.42-58.53 g) when compared to cleavage-stage embryo culture. We noted a very strong effect of clinic site on both LBR and BW, thus confounding between treatment practices and clinic site may have masked the effect of culture conditions. LIMITATIONS REASONS FOR CAUTION: Larger datasets with more inter-centre variation are also needed, with key embryo culture variables comprehensively recorded in national treatment registries. WIDER IMPLICATIONS OF THE FINDINGS: This study is the largest investigation of laboratory environmental effects in IVF on both LBR and singleton BW. Our findings largely agree with the literature, which has failed to show a consistent advantage of one culture media type over another. However, we noted some association of LBR with medium type, and the duration of embryo exposure to laboratory conditions (blastocyst culture) was associated with both LBR and singleton health at birth. Because of the strong effect of clinic site noted, further randomized controlled trials are needed in order to reliably determine the effect of embryo culture on IVF success rates and the growth and health of subsequent offspring. STUDY FUNDING/COMPETING INTERESTS: This study was funded by the EU FP7 project grant EpiHealthNet (FP7-PEOPLE-2012-ITN -317 146). The authors have no competing interests to declare.