The relationship between first-trimester pregnancy-associated plasma protein-A levels and intrapartum fetal distress development

To investigate the relationship between the development of intrapartum fetal distress and serum pregnancy-associated plasma protein-A (PAPP-A) levels measured during first-trimester aneuploidy screening tests. This retrospective study included 283 uncomplicated pregnancies that resulted in full-term live births via spontaneous labor or with the induction by oxytocin. Cases were divided into two groups based on whether their first-trimester PAPP-A multiple of the median (MoM) levels were ≤0.5 (Group 1, n=75) or >0.5 (Group 2, n=208). As primary end points, the rate of cesarean section (C/S), the rate of C/S due to fetal distress, and the umbilical artery blood pH values in cases of C/S for fetal distress were compared between the two groups. Statistical analyses were performed using the Chi-square test and independent samples t-test. P≤0.05 were considered statistically significant. The mean gestational age at birth and the birth weights were significantly lower in Group 1 than in Group 2 (p=0.002 and p=0.007, respectively). Although the rate of C/S was similar between the groups (p=0.823), the rate of C/S due to fetal distress was significantly higher in Group 1 than in Group 2 (68.4% vs. 42%, respectively; p=0.050) and the mean umbilical artery blood pH value for C/S deliveries indicated by fetal distress was lower (p=0.048) in Group 1 than in Group 2. When the mode of delivery was analyzed according to the application of labor induction, both the C/S delivery rates (31.6% in Group 1 and 31.7% in Group 2; p=0.992) and C/S delivery rates due to fetal distress (66.7% in Group 1 and 46.2% in Group 2; p=0.405) were similar in both groups. Low PAPP-A levels (≤0.5 MoM) in the first trimester are associated with the risk of intrapartum fetal distress development and the likelihood of C/S for fetal distress. Nonetheless, this risk is not affected by labor induction.