PP047. Fetal gender specific differences in markers of placentation and maternal adaptation to pregnancy - The generation R study.

Background: Evidence indicates a gender specific interaction between the mother, placenta and fetus in which maternal adaptation to pregnancy and outcome partly depends on fetal gender.

Objective: This study assesses fetal gender specific differences in placental biomarkers and uteroplacental vascular resistance. Methods Within the Generation R Study, in 1st and 2nd trimester (median 13.3 and 20.4 wks) blood samples were drawn to assess soluble fms-like tyrosine kinase (s-Flt1), placental growth factor (PLGF) and plasminogen activator inhibitor 2 (PAI-2). Uteroplacental resistance was assessed by mean pulsatility index (PI) of the uterine and umbilical arteries in the 2nd trimester. Mann-Whitney U and Student's t-test were performed to assess associations of gender on the above mentioned factors.

Results: In total 8631 women were included (4274 female and 4357 male fetuses). From these women, 172 had a pregnancy complicated by pre-eclampsia (1.9%). Fetal sex related differences in placental biomarkers, being most pronounced in non pre-eclamptic pregnancies (Table 1). Differences were also observed between early (<34wks) and late onset pre-eclamptic women (>34wks).

Conclusions: This study shows that maternal adaptation to pregnancy varies by fetal gender, suggesting gender specific differences in placentation and placental function. The differences between pre-eclamptic and non pre-eclamptic women, and among pre-eclamptic women, suggest that different mechanisms apply to pre-eclamptic pregnancies.