Prematuridade e baixo peso ao nascer e seus fatores de risco no município de João Pessoa, de 2001 a 2009

Abstract

Low birth weight (LBW) is defined by the World Health Organization as birth weight below 2500 g. It is considered the most relevant single factor of infant and childhood mortality and morbidity, with impact on growth and neuropsychomotor development. It is also likely to cause several diseases in adults. Prematurity, defined as birth at gestational age less than 37 weeks, is also considered one of the main reasons of neonatal mortality. This study aims at determining the prevalences of LBW and prematurity among single liveborn infants of mothers living in the city of João Pessoa between 2001 and 2009, as well as their distribution over time, and identifying risk factors for their occurrence. It is a cross-sectional study and data were collected from the files of the Liveborn Information System for the 2001-2009 period. The study included all records of liveborn infants of single pregnancy. Variables used in the study were: newborn sex, weight at birth, mother's age, school education level, marital status, number of prenatal medical appointments, gestational age, type of pregnancy and type of delivery. Prevalences of LBW and prematurity outcomes were determined for each year and also for the whole studied period. Univariate and multiple logistic regression models specific for each outcome were used to calculate the odds ratio (OR) and their 95% confidence intervals (CI). In the studied period there were 101.005 births, weight average of 3222,74 g (standard deviation: 544,24) and equal distribution concerning sex. LBW and prematurity prevalence were 7,2% and 5,8%, respectively. There was a rise in preterm deliveries throughout this period, while LBW rate remained steady. Most deliveries took place in hospital (99,8%), most of them by caesarean section from 2004 on. Most mothers were 20-34 years old, single, who spent 8 or more years in school, and had 4 or more prenatal medical appointments. There was a statistically significant drop in the percentage of teenage mothers throughout this period (22,8% to 17,8%, p=0,001). LWB was more likely among mothers younger than 20 and older than 35 years old (OR=1,23; 95%CI: 1,14¿1,33 and OR=1,33; 95%CI: 1,19¿1,48 respectively), who were single (OR=1,13; 95%CI: 1,05¿1,21), who had fewer than four prenatal medical appointments (OR=1,84; 95%CI: 1,68¿2,01), and had preterm newborn babies (OR=56,32; 95%CI: 52,49¿60,44) and gave birth to baby girls (OR=1,47; 95%CI: 1,38¿1,56). Concerning prematurity, risk factors were mother age below 20 (OR=1,23; 95%CI: 1,14-1,32), equal or over 35 years old (OR=1,34; 95%CI: 1,22¿1,47), number of prenatal medical appointments below 4 (OR=2,51; 95%CI: 2,32¿2,72) and delivery through caesarean section (OR=1,21; 95%CI: 1,14¿1,29). It can be concluded that, differently from what has been observed in other places, there was a fall in the number of teenage mothers in João Pessoa; that insufficient prenatal medical appointments, an avoidable factor, still persists and increases the likelihood of prematurity and low weight; and that the number of cases of preterm newborn infants weighing more than 2500 g is growing, following the rise in the number of caesarean sections.