EP17.44: Biochemical studies in the first trimester and the risk of preterm birth regardless of cause

The study aimed to assess if biochemical measurements of pregnancy-associated plasma protein-A (PAPP-A) and free beta-human chorionic gonadotropin (fbHCG), in both raw and normalised forms (multiple of medians - MoM), correlate with preterm labour (PTL), regardless of its spontaneity or iatrogenicity. Our cohort consisted of 664 patients who had first trimester prenatal screenings, including biochemical assessments between 11 and 13+6 weeks of gestation, followed by tracking the gestational age at delivery. We analysed the median concentrations of these parameters, focusing on two outcomes: PTL < 35 weeks vs > 34 weeks, and PTL (< 37 weeks) vs full-term pregnancy. Comparing median concentrations of biochemical markers, we observed significantly lower PAPP-A MoM levels in preterm labour (PTL) cases < 35 weeks (MoM = 0.91 vs 1.04, p < 0.05). This trend of reduced PAPP-A values persisted in patients with preterm births (<37 weeks), for both raw and normalised data. In the group of patients < 37 weeks gestation, we also noted a lower concentration of fb-HCG in both normalised and raw forms. Decreased PAPP-A MoM concentration was identified as a primary risk factor for PTL (see table 1). In preterm birth cases, we observed lower fbHCG and PAPP-A values between 11 and 13+6 weeks of gestation. The decreased concentration of PAPP-A MoM appears to be the most significant risk factor.