Elevated progesterone and its impact on birth weight after fresh embryo transfers.

PURPOSE: The purpose of the study was to examine the association between serum progesterone levels on the day of hCG administration and birth weight among singleton live births after fresh embryo transfer. METHODS: This study was conducted as a retrospective cohort database analysis on patients who underwent IVF treatment cycles from January 2004 to April 2012. The study was performed at a University affiliated private infertility practice. All cycles that had achieved a singleton live birth after fresh embryo transfer and for which progesterone was measured on the day of hCG administration were examined. Generalized linear models were used to calculate mean birth weight and z-scores. RESULTS: We analyzed 817 fresh IVF embryo transfers in which birth weight, gestational age, and progesterone (ng/mL) level on day of hCG administration were documented. While there was a decrease in birth weight as progesterone quartile [≤0.54; >0.54 to ≤0.81; >0.81 to ≤1.17; >1.17 ng/mL] increased, the difference in mean birth weights among the four quartiles was not statistically significant (p = 0.11) after adjusting for maternal age and peak estradiol levels. When dichotomizing based on a serum progesterone considered clinically elevated, cycles with progesterone >2.0 ng/mL had a significantly lower mean singleton birth weight (2860 g (95% CI 2642 g, 3079 g)) compared to cycles with progesterone ≤2.0 ng/mL (3167 g (95% CI 3122 g, 3211 g) p = 0.007)) after adjusting for maternal age and estradiol. CONCLUSION: We demonstrated that caution should be exercised when performing fresh embryo transfers with elevated progesterone levels and in particular with levels (>2.0 ng/mL) as this may lead to lower birth weight.