Pregnancy complications and placental histology in in vitro fertilization pregnancies with initial low serum β-hCG levels

Abstract

To assess perinatal outcomes and placental findings after invitro fertilization (IVF) with an initial low serum β-human chorionic gonadotropin (hCG). A retrospective cohort study. University-affiliated tertiary hospital. Low serum β-hCG after transfer, defined as the low 10th percentile for the cohort on day 16 embryo age (low β-hCG group), compared with an initial serum β-hCG at or above the low 10th percentile (control group). Live singleton births after IVF between 2009 and2017. Primary outcomes were placental findings, including anatomic, inflammatory, vascular malperfusion, and villous maturation lesions, as categorized according to the Amsterdam Placental Workshop Group Consensus. Secondary outcomes included obstetric and perinatal outcomes. The low 10th percentile of β-hCG results corresponded to 149 mUI/mL. There were 103 cases in the low β-hCG group, and 928 in the control group. Maternal demographics were similar between the groups, whereas blastocyte transfer was more common in the control group. Deliveries in the low β-hCG group were associated with an increased rate of preterm births, 15.5% vs. 8.1%, which maintained significance after adjustment for confounders. Placentas in the low β-hCG group were notable for a high rate of velamentous cord insertion, 19.4% vs. 7.7%, single umbilical artery 3.8% vs. 0.6%, and histological maternal vasculopathy, 10.6% vs. 4.8%. Live births after IVF with an initial low β-hCG level are associated with a twofold increase in preterm births and placental gross and histological changes. It may thus be considered to observe such cases in a high-risk pregnancy setting.