BackgroundLow birth weight (LBW) newborns present different health outcomes when classified in different birth weight strata. This study evaluated the relationship of birth weight with Infant mortality (IM) through the influence of biological, social, and health care factors in a time series.MethodsRetrospective cohort study with data collected from Information Systems (Live Births and Mortality). The mortality trends were performed for each birth weight stratum: extremely low, < 1000 g; very low, 1000–1499 g; low, 1500–2499 g; insufficient, 2500–2999 g; adequate, 3000–3900 g; and macrosomia, > 4000 g. Chi-square tests analyzed IM rates. Sequential Poisson regression analyzed the impact of the determinant factors.ResultsA total of 277,982 newborns were included in the study and 2088 died before their first year. There was a tendency for a decrease in mortality in all strata of weight. With the exception of macrosomics, all other strata had a higher risk for IM when compared with adequate birth weight. Extremely LBW newborns presented higher risk for mortality when born in a public hospital. A higher percentage of infant deaths were associated with lower maternal age and lower schooling for all strata. Prenatal care with less than three visits demonstrated a risk for IM in low, insufficient, and adequate birth weight strata. The cesarean section was a protective factor for IM in Extremely and Very LBW strata and it was a risk factor in adequate birth weight stratum.ConclusionsLBW had a greater association with IM, especially those children of younger mothers and those born in public hospitals.

ObjectiveTo analyze the trend of low birth weight (LBW) and its determinants in Brazilian state capitals between 1996 and 2011. We intended to determine which variables are associated with LBW during the period studied.MethodsThis is a cross-sectional study that used data from the National Information System of Live Births from 26 state capitals and Brasilia (the federal capital), divided into five geographical regions. The Average Annual Percentage of Change (AAPC) was used to assess the possible time trend in the low birth weight rates for considering all regions together and each region separately, according to each variable, and the Poisson regression was calculated in order to demonstrate time trends in low birth weight and the impact of variables (age and educational maternal level, antenatal visits, type of delivery, and gestational age) during the period. All variables were analyzed together using the Poisson regression as well.ResultsFrom the total of 11,200,255 live births used in this study, there was a significant reduction in the number of live births, especially in the more developed regions. The low birth weight rate was 8 %, and it was stable during the period. Considering regional trends, the rate was higher in the Southeast and South regions, and significantly higher in the North, Northeast, and Central West regions. Improvements in maternal education and antenatal care coverage reduced the risk for low birth weight in all regions. Also, there was an increase in caesarean sections in all regions, with a small impact on low birth weight rates.ConclusionsImprovements in education and health care reduced the risk for low birth weight in all Brazilian regions during the period of study. Trends in low birth weight rates and the associated factors differ from region to region, showing different stages of demographic, epidemiological and developmental transition in Brazil. The present study was approved by the Research Ethics Committee at the Hospital de Clínicas de Porto Alegre (Protocol 120323).

The article assessed the quality of completion of the maternal school variable in Brazilian state capitals and its regional distribution, based on the Brazilian Information System on Live Births (SINASC) with processed data from live birth certificates. A descriptive study was conducted in the time series from 1996 to 2013, with a total de 12,062,064 births, of which 11,442,494 (94.86%) had valid information on the maternal schooling variable. The results were calculated as the number of incomplete results in the variable per 1,000 live births, and the trend was assessed with the Joinpoint software, version 4.3.1. According to regional analysis, the South of Brazil showed a downward trend in incompleteness of maternal schooling throughout the study in all the state capitals of that region. Most of the country's other state capitals also showed improvement in the variable's completeness. However, there were different trends in some state capitals, even with greater incompleteness at the end of the period when compared to the beginning. SINASC proved to be a valuable source of data on mothers and their newborns, besides information on conditions in labor, delivery, and birth in the country. Maternal schooling, considered an important factor for obstetric and neonatal outcomes, is particularly useful for elaborating and evaluating policies and measures in maternal and child health. Thus, to achieve maximum completeness in data on this variable requires joint effort by health professionals and administrators, thereby guaranteeing the data's trustworthiness.