First-trimester serum markers and obstetric risk in a population with a high prevalence of obesity

Background: Early identification of pregnant women at risk of developing intrauterine growth restriction, preeclampsia, preterm birth, stillbirth, among other complications would allow more intensive surveillance to reduce the risk of severe disease. We aimed to study whether low levels of maternal serum markers PAPP-A and BHCG are associated with adverse pregnancy outcomes in an obese population. Methods: Cases were obtained from a cohort of 9111 patients who attended first trimester screening. We included women with PAPP-A and/or BHCG below the 5th percentile. A randomized group of women with serum markers above the 5th percentile was used as control group. Results were adjusted for age, parity, smoking status, BMI or reproductive techniques. Results: Prevalence of obesity was 20,7%. We found 382 women with PAPP-A below the 5th percentile, 325 with BHCG below the 5th percentile, 50 with both markers low, and recruited 1417 controls. The cases with low PAPP-A were significantly more likely to experience abortion, preeclampsia, low birth weight, preterm birth, or gestational diabetes. Low BHCG was significantly associated with gestational hypertension. Low BHCG and PAPP-A in the same patient correlated with abortion, early preeclampsia and preterm birth. Conclusions: Low levels of maternal serum markers correlate with adverse pregnancy outcomes in an obese population. We recommend to develop further calculators of obstetric risk to improve positive predictive value and to establish a maternal-fetal surveillance plan.