Prognostic factors for low birthweight repetition in successive pregnancies: a cohort study

Data were collected by hospital-based interviews. Newborns were weighed and measured. Gestational age was defined according to the date of last menstrual period, ultra-sound scan before the 20th week of pregnancy or the Dubowitz method. Mothers who reported at least one LBW newborn in the two previous gestations were included. Prevalence ratios (PR) and 95% confidence intervals were estimated from Poisson Regression. All estimates were adjusted for parity.A total of 4558 births were identified in 2004, and 565 met inclusion criteria, out of which 86 (15.2%) repeated LBW in 2004. Among mothers with two LBW babies before 2004, 47.9% presented LBW recurrence. Belonging to the highest socio-economic stratum (PR 0.89; 0.01-0.46) and gaining ≥ 10 kg during pregnancy (PR 0.09; 0.01-0.77) were protective against LBW recurrence. Higher risk of LBW recurrence was observed among mothers with higher parity (≥3 previous deliveries; PR=1.93; 95% CI 1.23-3.02); who had given birth to a previous preterm baby (PR=4.01; 2.27-7.10); who delivered a female newborn in current gestation (PR=2.61; 1.45-4.69); and that had not received adequate antenatal care (PR=2.57; 1-37-4.81).Improved quality of antenatal care and adequate maternal weight gain during pregnancy may be feasible strategies to prevent LBW repetition in successive pregnancies.Low birthweight (LBW) defined as birth weight lower than 2500 grams is an important infant mortality and morbidity predictor [1,2]. Birthweight derives basically from two processes: length of pregnancy and fetal growth rate. Hence, LBW might be caused either by a short gestational period (preterm birth) or by intrauterine growth restriction (small for gestational age - SGA) and even by a combination of both factors. A meta-analysis about LBW released in 1987 [3] based on English and French literature, identified 43 possible risk factors to the occurrence of LBW. The same study pointed out the fact that some mothers repeatedly deliver babies of similar