The association of maternal serum biomarkers and birth weight in twin pregnancy: a retrospective cohort study.

We retrospectively reviewed the medical records of 524 women with twin pregnancies who underwent antenatal care and gave birth in the past 12 years. Birth weight (BW) data were classified into three groups. We analysed the association between maternal serum biomarkers and BW in twin pregnancies using multiple logistic regression analysis. There were significant differences in the MoM values of pregnancy-associated plasma protein-A (PAPP-A), unconjugated oestriol (uE) and inhibin A between low BW and healthy newborns. The inhibin A value was significantly higher in women with small-for-gestational-age (SGA) foetuses and the PAPP-A, and uE values were lower in the SGA group than in the other groups using the generalised linear mixed model (hierarchical modelling considering cluster effects for twins). Maternal serum biomarkers, including PAPP-A, uE, and inhibin A, may be associated with SGA in twin pregnancy. Our results might provide useful information for SGA prediction during prenatal period in twin pregnancy. IMPACT STATEMENT The SGA is more frequent in twin pregnancies than in singleton, but there is no clearly identification of the aetiology of SGA. Further, most studies have been conducted in singleton pregnancies. The association of each maternal serum marker with SGA was assessed in the current study, and it is demonstrated that the levels of PAPP-A and uE in maternal serum of SGA foetuses were significantly lower than those in the other groups. In contrast, the levels of inhibin A were significantly increased in the SGA. The maternal serum biomarker of inhibin A was a more valuable predictive factor for SGA prediction in twins. The results of this study can be used in counselling prenatal screening. Further prospective research is needed to combine with ultrasound growth parameters, which can be generalised for the prediction of SGA in twins.