Correlation between serum markers in the second trimester and preterm birth before 34 weeks in asymptomatic twin pregnancies

Objective: To determine the correlation between the levels of serum markers in the second trimester and preterm birth before 34 weeks in asymptomatic twin pregnancies. Methods: We conducted a retrospective review of the medical records of 102 asymptomatic twin pregnancies delivered at Chilgok Kyungpook National University Hospital between March 2014 and February 2020. Participants were divided into two groups, based on delivery before and after 34 weeks of gestation. Results of the quad test performed at 15–18 weeks and the complete blood count done at 24–28 weeks were compared. Results: Preterm birth before 34 weeks of pregnancy was associated with higher levels of maternal α-fetoprotein (1.04 vs 0.98, multiple of median [MoM], P = 0.006), human chorionic gonadotropin (1.76 vs 1.31, MoM, P = 0.000), and inhibin A (1.78 vs 1.04, MoM, P = 0.000). Positive correlations were observed between gestational age at delivery and white blood cell (WBC) markers. Women with preterm delivery had decreased WBC counts (8180 vs 9405 × 10³/µl, P = 0.019) and neutrophil:lymphocyte ratios (3.85 vs 4.92, P = 0.001). Conclusion: Serum marker levels in the second trimester can be indicators of preterm delivery before 34 weeks in asymptomatic twin pregnancies.