Impact of Maternal Age on Birth Outcomes: A Population-Based Study of Primiparous Brazilian Women in the City of São Paulo

Abstract

The aim of this study is to analyse the impact of maternal age at first birth on low birth weight, preterm birth and low Apgar scores at one minute and at five minutes among live births delivered to primiparous Brazilian women in the city of São Paulo. Analyses were based on 73,820 birth records from the 1998 birth cohort. Logistic regression was used to assess the association between maternal age and each outcome variable, controlling for the following risk factors: delivery mode, plurality, sex, maternal education, number of prior losses, prenatal care, race, parity and community development. Maternal ages below 20 and above 30 years were significantly associated with the risks of low birth weight and preterm birth, but no association was found between maternal ages and Apgar score, with the exception that ages 15-19 reduced the odds of a low one-minute score. Even though this result seems to be inconsistent, low birth weight, preterm birth and low Apgar scores measure different dimensions of newborn well-being, and the association of each measure with maternal age is expected to diverge.

The Impact of Early Age at First Childbirth on Maternal and Infant Health

“…Of these, 11 reported results for LBW only, and nine presented results for VLBW (<1500 g) as well as MLBW (1500–2499 g) or LBW. The four studies conducted in middle income countries 21,30–32 reported that LBW was significantly higher among infants of younger mothers (Table 5). Sixteen of the 20 studies were conducted in high income countries: 13 in the United States, 18,33–44 and one each in Saudi Arabia, 45 Australia, 23 and France 22 .…”

“…Of these, 18 were from high income countries, 18,22,23,29,34–36,38,39,41–43,45–50 five were from middle income countries, 19,21,30–32 one was from a low income country, 51 and one analysed data from countries of differing income levels 52 . Four out of five studies from middle income countries found that PTB was significantly more common among infants of younger mothers, 19,21,31,32 as did most of the studies from high income countries. The study from Nepal 51 had wide CI, likely because of a small sample size, but the point estimates still indicate a possible adverse effect of adolescent pregnancy on PTB.…”

The Association of Maternal Age with Birth Weight and Gestational Age: A Cross-Cohort Comparison.

“…This suggests that, at least in some previous studies, controlling for maternal education alone may not have been sufficient to eliminate socio-economic confounding and may explain why some of the reports in the literature are in disagreement with our present findings. 17,35 An additional important finding of our study is that by combining all four cohorts, we had adequate statistical power to examine whether very young maternal age (<16 years) was associated with adverse perinatal outcomes. Very few studies have sufficient statistical power to precisely estimate the association between very young maternal age at birth and adverse perinatal outcomes.…”

Hour of birth and birth assistance: From a primate to a medicalized pattern?

“…Several authors (Astolfi et al, 1999;Joseph et al, 2003;Machado, 2006;Wilkinson et al, 1998) justify the need of extending medicalization of birth because of the rising rates in late maternal age, primiparity, and multiple pregnancies, which are associated with risky pregnancies and negative birth outcomes. In addition, the increasing proportion of deliveries by immigrant mothers-which in 2009 represent 20.9% of all births in Spain-might also affect the timing of birth.…”