First-trimester maternal serum screening and the risk for fetal distress during labor.

OBJECTIVE: The purpose of this study was to assess whether low pregnancy-associated plasma protein-A (PAPP-A) levels in the first trimester are related to the risk of emergency cesarean section delivery (CS) for fetal distress during labor and fetal intrapartum acidemia.

STUDY DESIGN: We prospectively studied patients who requested first-trimester biochemical screening for Down syndrome.

RESULTS: Among the 1037 women who were enrolled, 152 women (14.7%) had a low first-trimester PAPP-A value, and 855 women (85.3%) had a normal first-trimester PAPP-A value. Excluding elective CS, 19 of 117 women (16.2%) with low PAPP-A values vs 59 of 749 women (7.9%) with normal PAPP-A values underwent CS for concerning fetal status during labor (P = .003; odds ratio, 2.27; 95% confidence interval, 1.30-3.97). This difference remained significant after correction for possible confounders (hypertension, preterm delivery, small for gestational age, labor induction). Among these 78 women, umbilical artery pH was significantly lower in fetuses from mothers with low vs normal PAPP-A values (pH = 7.19 [range, 6.95-7.39] vs pH = 7.26 [range, 7.02-7.39]; P = .022).

CONCLUSION: Low PAPP-A levels at first-trimester screening are associated independently with higher rates of emergency CS for nonreassuring fetal status during labor and lower pH.