Association between Gestational Weight Gain and Small for Gestational Age in Underweight Pregnant Women

Abstract

Objectives: To compare the rate of small-for-gestational age (SGA), low birth weight (LBW), and other pregnancy outcomes between underweight pregnant women who had adequate and inadequate gestational weight gain (GWG). Materials and Methods: A total of 300 singleton, uncomplicated, underweight pregnant women were included in a retrospective cohort study. Study group consisted of 100 women who had inadequate GWG and another 200 women who had adequate GWG were in comparison group. Data were retrieved from medical records, including baseline and obstetric characteristics, trimester-specific and total weight gain, delivery data, and pregnancy outcomes. Rate of SGA and other pregnancy outcomes were compared between the 2 groups. Results: Both groups were comparable in terms of age, BMI, and parity. Compared with women with adequate GWG, those with inadequate GWG had significantly lower weight gain in every trimester. Women with inadequate GWG were significantly more common to have preterm delivery (11% vs. 2%, p = 0.001), LBW (29% vs. 6%, p < 0.001), and SGA (18% vs. 6.5%, p = 0.002). Logistic regression analysis showed that 2nd trimester weight gain ≤ 7 kg was the only independent associated factor for SGA (adjusted odds ratio (OR) 9.92, 95% confidence interval (CI) 2.06-47.68, p = 0.004). On the other hand, inadequate GWG was the only independent associated factor for LBW (adjusted OR 5.82, 95%CI 2.11-16.0, p = 0.001). Conclusion: Underweight pregnant women who had inadequate GWG significantly increased risk of preterm delivery, LBW, and SGA. Second trimester weight gain ≤ 7 kg was independently associated with SGA and inadequate GWG was independently associated with LBW.