The association of maternal age with birthweight and gestational age: a cross-cohort comparison.
Bottom Line: Very young (<16 years) maternal age was also associated with both outcomes even after full SEP adjustment.Confounding by SEP explains much of the excess risk of LBW and preterm among babies born to teenage mothers as a whole, but not for mothers aged <16 or ≥ 35 years.Given that the proportion of women becoming pregnant at <16 years is smaller than for those ≥ 35 years, the population burden is greater for older age.
Affiliation: Department of Epidemiology, Federal University of Pelotas, Pelotas, Brazil.Show MeSH
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Mentions: There were too few adolescent mothers aged <16 years in each individual cohort to reliably estimate the odds of outcomes compared with the reference group. Since there was no strong evidence for the interaction between maternal age categories and LBW by cohort study (unadjusted and adjusted model had P = 0.8 and P = 0.9, respectively), we combined the cohorts. Figure 1 shows that with all four studies combined, there are important increases in the odds of LBW in those <16 years and >34 years, compared with the reference group of 25–29 years (see also Table S3). In addition, adjustment for confounders tended to attenuate the ORs associated with all age groups except that of mothers 30 years or older, for which adjustment increased the OR. In a similar manner, associations of maternal age with preterm birth did not differ between the four studies. Results with preterm birth as the outcome were generally similar to those for LBW (Figure 2). However after adjustment for confounders, both adolescent and older mothers continued to show a strong evidence of increased odds for preterm birth (see also Table S3).
Affiliation: Department of Epidemiology, Federal University of Pelotas, Pelotas, Brazil.