Correlation between Maternal Weight Gain in Each Trimester and Fetal Growth According to Pre-Pregnancy Maternal Body Mass Index in Twin Pregnancies

Abstract

Background andObjectives: This study aimed to determine the correlation between maternal weight gain in each trimester and fetal growth according to pre-pregnancy maternal body mass index in twin pregnancies. Materials and Methods: We conducted a retrospective review of the medical records of 500 twin pregnancies delivered at 28 weeks’ gestation or greater at a single tertiary center between January 2011 and December 2020. We measured the height, pre-pregnant body weight, and maternal body weight of women with twin pregnancies and evaluated the relationship between the maternal weight gain at each trimester and fetal growth restriction according to pre-pregnancy body mass index. Results: The overweight pregnant women were older than the normal or underweight pregnant women, and the risk of gestational diabetes was higher. The underweight pregnant women were younger, and the incidence of preterm labor and short cervical length during pregnancy was higher in the younger group. In normal weight pregnant women, newborn babies’ weight was heavier when their mothers gained weight, especially when they gained weight in the second trimester. Mothers’ weight gain in the first trimester was not a significant factor to predict fetal growth. The most predictive single factor for the prediction of small neonates was weight gain during 24−28 and 15−18 weeks, and the cutoff value was 6.2 kg (area under the curve 0.592, p < 0.001). Conclusions: In twin pregnancy, regardless of the pre-pregnant body mass index, maternal weight gain affected fetal growth. Furthermore, weight gain in the second trimester of pregnancy is considered a powerful indicator of fetal growth, especially in normal weight pregnancies.

Keywords: fetal growth; maternal complications; maternal weight gain; neonatal outcomes; twin pregnancy.

Figure 1

Area under the curve (AUC) of the predictive values for maternal weight and weight gain during pregnancy for the small for gestational age (SGA) group in twin pregnancy. (A) Among various weight gain values by pregnancy period, weight gains during 24–28 and 15–18 weeks, i.e., during the second trimester of pregnancy, were the most significant predictive factor, with an AUC = 0.592 and a cutoff value of 6.2 kg. (B) The weight gain value for each pregnancy trimester was simultaneously analyzed, and the AUC value that can predict the rate of SGA was confirmed. The blue line indicates weight gain between 24–28 and 15–18 weeks and between 20–24 and 15–18 weeks, with an AUC of 0.585 and cutoff values of 6.8 and 4 kg, respectively. The orange line indicates the SGA prediction using weight gain in the first trimester, weight gain in the second trimester, weight gain between 20–24 and 15–18 weeks, and weight gain between 24–28 and 20–24 weeks, with cutoff values of 0.6, 7, 3.5, and 3.5 kg, respectively (AUC = 0.583).