[Mid-gestational glucose levels and newborn birth weight: birth cohort study]

To understand the association between the blood glucose levels of pregnant women in second trimester detected by 75 gram oral glucose tolerance test (OGTT) and the birth weight of neonates.

Demographic information collection and OGTT were conducted for 3 081 pregnant women at ≤14 gestational weeks and 24-28 gestational weeks respectively. Multiple logistic regression analysis was done to identify the factors associated with the birth weight and the risks of large for gestational age (LGA) in three levels (FPG, OGTT-1 h and OGTT-2 h) of OGTT percentile group, multiple linear regression analysis was used to evaluate the relationships between maternal glucose levels and neonate birth weight.

Pre-pregnancy obesity (24.0 kg/m2≤BMI<28.0 kg/m2) (OR=1.4, 95%CI:1.0-2.0, P=0.029) and gestational diabetes mellitus (OR=2.4,95% CI: 1.8-3.2, P<0.001) were the risk factors. Pre-pregnancy underweight (BMI<18.5 kg/m2) (OR=1.6, 95%CI: 1.2-2.2, P=0.003), preeclampsia (OR=4.0, 95%CI: 1.9-8.4, P<0.001) increased the risk for small for gestational age (SGA). Multiple linear regression analysis showed neonate birth weight was positive correlated with maternal glucose levels (β were 91.99, 33.60, 32.00, respectively, P<0.001). Percentile groups of each OGTT level was linearly positive associated with increased mean value of neonate birth weight, and so with the risk of LGA.

There were positive correlations between maternal glucose levels and neonate birth weight. The risk of LGA increased with the maternal glucose levels, but there was no statistical association between SGA and maternal glucose levels. FPG level is one of the predictors of LGA. Active surveillance and control of maternal glucose level can effectively reduce the risk of LGA.