P-769 Endometrial thickness is not associated with birthweight as well as serum levels of pregnancy-associated plasma protein-A: a retrospective analysis of 560 newborns following frozen cycles

Abstract

Abstract Study question Does endometrial thickness (EMT) affect birthweight and maternal serum evels of pregnancy-associated plasma protein-A (PAPP-A) in singleton pregnancies following frozen-thawed blastocyst transfer (FET)? Summary answer EMT does not significantly affect birthweight and maternal serum evels of PAPP-A in singleton pregnancies following FET. What is known already Several studies have shown an association between EMT and low birth weight in pregnancies resulting from fresh embryo transfers. Supraphyiological levels of steroid hormone during ovarian stimulation may be responsible for poor fetal growth. Few studies have investigated the relationship between EMT and fetal growth potential in frozen-thawed embryo transfers. Study design, size, duration This retrospective study included women who underwent first-trimester combined screening for aneuploidy after frozen-thawed blastocyst transfer and subsequently delivered a singleton live birth after 24 weeks of gestations between January 2016 and July 2020 in a private IVF center. Participants/materials, setting, methods A total of 560 women met the inclusion criteria and were stratified into three groups based on the EMT percentiles: <7.7 mm (<10th percentile), 7.7–12 mm (10-90th percentile), and >12 mm (>90th percentile). The primary outcome measures were mean birth weight and mean PAPP-A level. A multivariable linear regression analysis was carried out to identify the association between birth weight and EMT after adjusting for variables found at < 0.1 level in the univariate analysis. Main results and the role of chance The mean birth weight was 3127 ± 783 g in those with EMT <7.7 mm 3225 ± 644 g in those with EMT 7.7-12 mm, and 3256 ± 599 g in those with EMT >12 mm (p = 0.577). The mean PAPP-A levels and PAPP-A<0.5 rates were similar in the groups, as well. In multivariate analysis, the number of previous ART attempts and maternal serum levvels of PAPP-A were found to be significant predictors of birth weight (p = 0.001 and p = 0.013, respectively). EMT was not a predictor of birth weight in both univariate and multivariate analyses. The multivariate logistic regression analysis indicated that the number of previous ART attempts was an independent factor for low birth weight (OR:1.39, 95%CI:1.09-1.76, p = 0.006). Limitations, reasons for caution The study has inheret limitations due to its retrospective nature. Further studies are needed to investigate the relationship between EMT and birth weight along with maternal serum levels of PAPP-A. Wider implications of the findings Our study provided a new angle of view for evaluating the association between EMT and neonatal birth weight by analyzing this association along with maternal serum levels of PAPP-A as a marker for placental function, suggesting that EMT is not an independent factor for neonatal birth weight. Trial registration number NA