Methods A retrospective cohort study of a total of 81 preterm infants at our centre with low birth weight and ≤32 weeks of gestation was performed. We analysed perinatal risk factors. Data are expressed as a function of gestational age (GA) <28 or between 28–32 weeks and birth weight defined as: extremely <1000 g, very low 1001–1500 g and low weight 1501–2000 g.

Results The mean maternal age was 30.3 ± 5.8 years. There were no statistically significant differences when comparing maternal age in according to birth weight (29.2 ± 5.7 vs. 31.5 ± 6.6 vs. 30.2 ± 4.6, p = 0.460 respectively) or gestational age (30.4 ± 5 vs. 30.3 ± 6, p = 0.964). The presence of maternal risk factors was very low: 3.7% were smokers, 2.5% had obesity. There were preeclampsia and diabetes gestational in 5 and 3 cases, respectively. Chorioamnionitis was diagnosed in 13.6% of pregnancies and 71.3% received antenatal steroids. The pregnancy was twins in 29.6% of cases. No significant differences were found when perinatal characteristics were examined in terms of birth weight, except for gestational diabetes (0% vs. 0% vs. 13.6% in low birth, p = 0,016). Maternal age did not influence in neonatal mortality (30.2 ± 5 years in preterm infants living vs. 30.7 ± 6 years in those died, p = 0.784.

Conclusions In our series, the presence of maternal risk factors was very low. We were not found significant differences in according to birth weight or impact on neonatal mortality.