A population-based study of the relationship between advanced maternal age and premature/early-term birth in Brazil.

OBJECTIVE: To verify whether advanced maternal age (AMA), defined as women of ≥35 years, is associated with premature and early-term birth in Brazil, according to the onset of labor (spontaneous or provider-initiated). METHODS: Cross-sectional population-based study. The "Birth in Brazil" study interviewed 23 894 puerperal women between 2011 and 2012, in all regions of Brazil. The current analysis included 17 994 adult mothers and their newborns (15 448 aged between 20-34 years, and 2536 ≥ 35 years). A propensity score was used to assess the likelihood of AMA women giving birth to premature or early-term infants (spontaneous or provider-initiated) compared to women aged 20-34 years. To balance the groups, we used maternal, prenatal, and childbirth characteristics. RESULTS: The general prematurity rate was 10.24%, of which the majority of births were spontaneous (55.73%). Conversely, early-term births were more often provider-initiated (54.81%). AMA did not increase the chance of premature births, whether spontaneous or provider-initiated. However, AMA was associated with a higher rate of provider-initiated early-term birth (OR = 1.48; 95% CI: 1.23-1.77). CONCLUSION: AMA alone does not contribute to premature birth; AMA's independent association with provider-initiated early-term birth may not be based solely on clinical indications.

Gestational weight gain adequacy for favourable obstetric and neonatal outcomes: A nationwide hospital-based cohort gestational weight gain for favourable obstetric and neonatal outcomes.

BACKGROUND & AIMS: Most Brazilian women fail to gain weight within recommendations during pregnancy but current guidelines about gestational weight gain was based on North American population analysis. There are no standardized recommendations developed from Brazilian population data, which should be particularly analysed due to ethnic and sociodemographic characteristics. This study analyses the gestational weight gain of Brazilian women with favourable obstetric and neonatal outcomes according to the pre-pregnancy body mass index, considering maternal sociodemographic characteristics. METHODS: We analysed data from the Birth in Brazil: national survey into labour and birth study, a nationwide hospital-based cohort carried out in 266 Brazilian hospitals from February/2011 to July 2012, including adult pregnant women who have no chronic diseases and who have single foetal gestation, born alive and without malformation. Favourable obstetric and neonatal outcomes considered were gestational age at birth greater than or equal to 37 and less than 42 weeks, birthweight between 2500 g and 4000 g, and birthweight suitable for gestational age. Sociodemographic characteristics were obtained from medical records and interviews. Weight and height information was obtained from the prenatal card or self-reported. The pre-pregnancy BMI was classified in low weight, normal weight, overweight, obesity I, obesity II, and obesity III. For the missing cases on pre-pregnancy weight or height, body mass index was imputed by multiple imputation prediction model. Gestational weight gain was the difference between the last weight before delivery and the pre-pregnancy weight and was presented as mean and confidence interval, mean and standard deviation, and percentiles distribution (10th to 90th) for each pre-pregnancy body mass index, thus compared to Institute of Medicine recommendations. RESULTS: The analysis included 8184 Brazilian women. The gestational weight gain was lower in women with less favoured social conditions. The mean gestational weight gain according to pre-pregnancy body mass index was within the Institute of Medicine recommendations, except for women with overweight or obesity class I, who have the mean weight gain higher than upper limit of the Institute of Medicine range. Gestational weight gain decreased with an increase in the categories of body mass index; the mean (±standard deviation) were: 15.41 kg (±5.53), 13.54 kg (±4.97), 12.45 kg (±5.86), 9.38 kg (±6.31), 7.15 kg (±6.43), and 5.04 kg (±7.10), for low weight, normal weight, overweight, and obesity I, II and III, respectively. Women had favourable obstetric and neonatal outcomes gaining less, within or more than the recommendations with higher range of variation amongst obesity classes I, II, and III which do not have specific ranges stated in Institute of Medicine guidelines. CONCLUSION: Brazilian women had favourable obstetric and neonatal outcomes gaining less, within or more than the Institute of Medicine recommendations. We highlight the need of population-based high-quality research to investigate the optimal GWG recommendations for this population.