Maternal pre-pregnancy underweight as a risk factor for the offspring: Survey of Neonates in Pomerania.

AIM: The aim was to investigate socio-economic risk factors for maternal underweight before pregnancy and then associations of underweight with neonatal outcomes. METHODS: Data of 3401 mother-child dyads from the population-based birth cohort Survey of Neonates in Pomerania (SNiP) were analysed. RESULTS: Bivariate analysis showed that underweighted mothers were younger, smoked more often, had a lower equivalent income and lower socio-economic status (employment status and/or educational level) compared to women with normal weight. The final prediction model revealed that only younger maternal age (OR = 0.93; 95%-CI = 0.90-0.97) and maternal smoking during pregnancy (OR = 2.52; 95%-CI = 1.74-3.66) were associated with underweight. Compared to women with normal pre-pregnancy BMI, underweight women had an increased chance of premature labour (OR = 1.73; 95% CI: 1.29-2.31) and a reduced placental weight. The offspring of underweight women had an increased risk of late preterm birth (OR = 1.82; 95% CI: 1.21-2.74) and birthweight < 2500 g (OR = 1.91; 95% CI: 1.23-2.95). CONCLUSION: Smoking during pregnancy and a younger age were identified as risk factors for maternal pre-pregnancy underweight which then was associated with late preterm birth and low birthweight.