科研人员报告说,在一年的某些时间受孕的女性可能容易出现早产等新生儿健康方面的问题。大量研究已经把出生的季节与身高、智商、心理健康、收入以及预期寿命等多种成年人的结果联系了起来。然而,近来的发现提示,与母亲的社会经济状态相比,出生季节可能不重要,因为年轻、贫穷、受教育不足、未成年和未婚的母亲倾向于在与最差的成年结果有关联的季节分娩。Janet Currie和Hannes Schwandt通过比较纽约市、新泽西和宾夕法尼亚州的647050名母亲的子女——总共生产次数超过140万次——从而探索了受孕季节与出生时的健康的关系。这组作者报告说,这项分析发现在5月受孕的新生儿比在一年的其他月份受孕的新生儿的早产率要高出10%,这可能反映了1月和2月季节性流感病例的剧增,而此时这些女性怀孕接近足月。此外,在夏季月份受孕的新生儿倾向于比其他新生儿重大约8到9克,这很可能是由于怀孕体重增加的季节性模式。这些结果无法通过诸如吸烟或婚姻状态等因素加以解释。这组作者提示,这些发现可能为诸如鼓励孕妇接种流感疫苗的公共政策提供信息。(生物谷 Bioon.com)
生物谷推荐的英文摘要
PNAS 10.1073/pnas.1307582110
Janet Currie and Hannes Schwandt
Within-mother analysis of seasonal patterns in health at birth
A large literature describes relationships between month of birth, birth weight, and gestation. These relationships are hypothesized to reflect the causal impact of seasonal environmental factors. However, recent work casts doubt on this interpretation by showing that mothers with lower socioeconomic status are more likely to give birth in months that are associated with poorer birth outcomes. Seasonality in the numbers of conceptions in different months can also induce a mechanical correlation between preterm birth and month of birth. This paper analyzes the seasonality of health at birth using a large sample of 647,050 groups of US siblings representing 1,435,213 children. By following the same mother over time, we eliminate differences in fixed maternal characteristics as an explanation for seasonal differences in health at birth. We find a sharp trough in gestation length among babies conceived in May, which corresponds to an increase in prematurity of more than 10%. Birth weight conditional on gestation length, however, is found to be strongly hump-shaped over the year, with 8–9 additional g for summer conceptions. We examine several potential mechanisms for explaining seasonality in birth outcomes that have generally been dismissed in the literature on seasonality in rich countries, notably disease prevalence and nutrition. The May trough in gestation length coincides with a higher influenza prevalence in January and February, when these babies are nearing full term, whereas the hump shape in birth weight is associated with a similar pattern in pregnancy weight gain.