Restrepo-Méndez María Clara, Lawlor Debbie A, Horta Bernardo L, Matijasevich Alicia, Santos Iná S, Menezes Ana M B, Barros Fernando C, Victora Cesar G
Department of Epidemiology, Federal University of Pelotas, Pelotas, Brazil.
Paediatr Perinat Epidemiol. 2015 Jan;29(1):31-40. doi: 10.1111/ppe.12162. Epub 2014 Nov 18.
We examined the associations of maternal age with low birthweight (LBW) and preterm birth in four cohorts from a middle- and a high-income country, where the patterning of maternal age by socio-economic position (SEP) is likely to differ.
Population-based birth cohort studies were carried out in the city of Pelotas, Brazil in 1982, 1993, and 2004, and in Avon, UK in 1991 [Avon Longitudinal Study of Parents and Children (ALSPAC)]. Adjustment for multiple indicators of SEP were applied.
Low SEP was associated with younger age at childbearing in all cohorts, but the magnitudes of these associations were stronger in ALSPAC. Inverse associations of SEP with LBW and preterm birth were observed in all cohorts. U-shaped associations were observed between maternal age and odds of LBW in all cohorts. After adjustment for SEP, increased odds of LBW for young mothers (<20 years) attenuated to the null but remained or increased for older mothers (≥ 35 years). Very young (<16 years) maternal age was also associated with both outcomes even after full SEP adjustment. SEP adjusted odds ratio of having a LBW infant in women <16 years and ≥ 35 years, compared with 25-29 years, were 1.48 [95% confidence interval (CI) 1.00, 2.20] and 1.66 [95% CI 1.36, 2.02], respectively. The corresponding results for preterm birth were 1.80 [95% CI 1.23, 2.64)] and 1.38 [95% CI 1.15, 1.67], respectively.
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.
我们在一个中等收入国家和一个高收入国家的四个队列中研究了母亲年龄与低出生体重（LBW）和早产之间的关联，在这两个国家中，母亲年龄按社会经济地位（SEP）的模式可能有所不同。
1982年、1993年和2004年在巴西佩洛塔斯市以及1991年在英国埃文（埃文父母与儿童纵向研究（ALSPAC））开展了基于人群的出生队列研究。对SEP的多个指标进行了调整。
在所有队列中，低SEP与生育年龄较小相关，但这些关联的程度在ALSPAC中更强。在所有队列中均观察到SEP与LBW和早产呈负相关。在所有队列中，母亲年龄与LBW几率之间呈U形关联。在调整SEP后，年轻母亲（<20岁）LBW几率增加减弱至零，但年长母亲（≥35岁）的LBW几率仍保持或增加。即使在完全调整SEP后，极年轻（<16岁）的母亲年龄也与这两种结局相关。与25 - 29岁相比，<16岁和≥35岁女性生育低出生体重婴儿的SEP调整优势比分别为1.48 [95%置信区间（CI）1.00, 2.20]和1.66 [95% CI 1.36, 2.02]。早产的相应结果分别为1.80 [95% CI 1.23, 2.64)]和1.38 [95% CI 1.15, 1.67]。
SEP的混杂解释了总体上青少年母亲所生孩子中LBW和早产额外风险的大部分，但对于年龄<16岁或≥35岁的母亲则不然。鉴于<16岁怀孕的女性比例低于≥35岁的女性，高龄的人群负担更大。
