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

Background: 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.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 high. The underweight pregnant women were younger, and the incidences of preterm labor and short cervical length during pregnancy was high. Especially in normal weight pregnant women, the heavier the weight of the newborn babies as the second trimester of pregnancy weight gain, the less significant the weight gain in the first trimester of pregnancy and fetal growth. The most predictive single factor for the prediction of small neonates was weight gain during 24-28 weeks 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.