[Effect of pregnant serum folate concentration on newborn's birth weight]

To study the effect of pregnant serum folate concentrations on the birth weight.

This study was a prospective cohort study. Pregnant women aged 18-45 who were examined and delivered in a county in Hebei Province from June 2016 to August 2018 and their newborns were included in the study. A total of 490 women were recruited and collected venous blood before the 20 th week of pregnancy. Basic information of women as well as their use of folic acid supplements was collected at the same time. Newborns' basic information, such as sex and birth weight, had been collected after delivery. The chemiluminescence method was used to determine the serum folate concentrations. Folate concentrations quartile were used as the cut-off point to divide subjects into four groups. The general linear model and multivariate unconditional Logistic regression analysis were used to study the effect of different serum folate concentrations on the infant birthweight.

The age of 490 pregnant women was(27. 9±4. 1) years. The serum folate value P50(P25, P75) was 12. 3(9. 0, 14. 5) ng/mL and its' detection time was(13. 7±2. 6) weeks. 49. 3%(242/490) newborns were male. The average gestational age of the newborns was(39. 1±1. 0) weeks and the average birth weight was(3403±425) g. The birth weight of four groups' newborns were(3408±456) g, (3405±450) g, (3427±418) g and(3374±378) g, respectively. General linear model analysis showed that there was no significant difference in the effect of serum folate levels before the 20 th week of gestation on the birth weight(serum folate concentration<9. 0 ng/mL(β=32. 24, P=0. 55), serum folate concentration 9. 0-12. 2(β=18. 01, P=0. 74), serum folate concentration 12. 3-14. 4(β=42. 27, P=0. 43)]. Multivariate unconditional Logistic regression analysis showed that the group with folate concentration above 14. 5 ng/mL can reduce the risk of small for gestational age(SGA) [(P=0. 02, OR=0. 08(95% CI 0. 01-0. 61)]. Comparing with ghe pregnant women whose serum folate concentration was in 9. 0-12. 4 ng/mL. Hovever, there was no significant difference between the pregnant serum folate levels and large for gestational age(LGA).

There was no significant correlation between serum folate concentrations and the birth weight. But higher folate level may reduce the risk of SGA.