Association of duration of embryo culture with risk of large for gestational age delivery in cryopreserved embryo transfer cycles.

OBJECTIVE: To examine the relationship between the day of embryo cryopreservation and large for gestational age (LGA) infants in women undergoing frozen embryo transfers (FETs) after cryopreservation on days 2-7 after fertilization and to compare the risk of the day of embryo cryopreservation to other possible risk factors of LGA after FET cycles. DESIGN: Retrospective cohort study. SETTING: Society of Assisted Reproduction Clinical Outcomes Reporting System. PATIENTS: Women undergoing FET cycles. INTERVENTION: Day of cryopreservation. MAIN OUTCOME MEASURE: Singleton LGA infant. RESULTS: A total of 33,030 (18.2%) FET cycles in the study group (n = 181,592) resulted in LGA infants during the study period of 2014-2019. There was an increase in LGA risk when cryopreservation was performed from day 2 (13.7%) to days 3-7 (14.4%, 15.0%, 18.2%, 18.5%, and 18.9%). In the log-binomial model, the risk increased compared with days 2-3 combined when cryopreservation was performed on days 5-7 (adjusted relative risk [aRR] 1.32, 95% confidence interval [CI] 1.22-1.44 for day 5, aRR 1.34, 95% CI 1.23-1.46 for day 6, and aRR 1.42, 95% CI 1.25-1.61 for day 7). Other factors most associated with LGA risk in the log-binomial model were preterm parity of >3 compared with 0 (aRR 1.82, 95% CI 1.24-2.69) and body mass index (BMI) of >35 kg/m2 compared with normal weight (aRR 1.94, 95% CI 1.88-2.01). Increasing gravity, parity, BMI, number of oocytes, and embryo grade were also associated with LGA in this model. Asian, Black, Hispanic, and combined Hawaiian and Pacific Islander were protective factors in the model compared with White patients. Low BMI (<18.5 kg/m2) was also considered a protective factor in the model compared with normal BMI. CONCLUSION: Duration of embryo culture was associated with an increased risk of LGA in this study cohort when controlling for known confounders such as maternal BMI and parity. This study sheds new light on the possible link between FET and LGA infants.

Factors associated with large-for-gestational-age infants born after frozen embryo transfer cycles.

Objective: To examine trends of frozen embryo transfer (FET) proportions and large-for-gestational-age (LGA) incidence and determine risk factors for LGA infants after FET. Design: Retrospective cohort study. Setting: Not applicable. Patients: Frozen embryo transfer cycles. Interventions: None. Main Outcome Measures: Singleton LGA infant. Results: The percentage of FETs increased from 20%-74% of transfers, whereas the rate of LGA among FET singleton births decreased from 18%-12% during 2004-2018. In a subanalysis of 127,525 FET-associated singleton live births during 2016-2018, patient factors associated with LGA were higher-than-normal maternal body mass index (body mass index [BMI], 25.0-29.9 kg/m2; adjusted relative risk [aRR], 1.31; 95% confidence interval [CI], 1.26-1.36; BMI, 30.0-34.9 kg/m2; aRR, 1.48; 95% CI, 1.41-1.55; and BMI, >35 Kg/m2; aRR, 1.68; 95% CI, 1.59-1.77) and ≥1 prior birth vs. none. Low maternal BMI (<18.5 vs. 18.5-24.9 kg/m2) and cycles involving patients who were non-Hispanic (NH) Asian/Native Hawaiian/Pacific Islander, NH Black, or Hispanic (compared with NH White) were at lower risk of LGA infants. Cycle factors associated with LGA included gestational carrier use (aRR, 1.25; 95% CI, 1.16-1.34) and donor sperm (aRR, 1.17; 95% CI, 1.10-1.25). Conclusions: Although the number and proportion of FET cycles increased from 2004-2018, the rate of LGA after FET decreased. Maternal BMI, parity, and race/ethnicity were the strongest risk factors for LGA infants after FET.

A Comparison of Prostaglandin Profile in Human Follicular Fluid Between White and Black/Hispanic Women.

The aim of the study is to compare prostaglandin (PG) profiles in human follicular fluid between White and Black/Hispanic women using data from a previously published study. A retrospective cohort study of 5 White and 5 Black/Hispanic women who underwent oocyte retrieval was conducted. Human follicular fluid was obtained from the first follicle entered at time of oocyte retrieval for patients undergoing in vitro fertilization cycles (IVF). PG levels were compared using mass spectroscopy with known standards to quantify PG levels. Five White women were matched with 5 Black/Hispanic women with diagnosis. Both cohorts had similar levels of age, body mass index, and IVF cycle characteristics. There were no statistical differences in PG profiles (PGE2, PGF1α, PGF2α, or 8 iso-PGF1α). In this small repeat analysis of previously studied data, there were no differences noted in PG profiles in follicular fluid. Larger studies are needed to verify this finding. This study further demonstrates the lack of representation of minority patients in studies.