Population, Policy and Practice Research and Teaching Department, UCL Great Ormond Street Institute of Child Health, London, UK.
Department of Geography, University of Cambridge, Cambridge, UK.
Am J Hum Biol. 2021 Nov;33(6):e23566. doi: 10.1002/ajhb.23566. Epub 2021 Jan 15.
Evolutionary perspectives on human childbirth have primarily focused on characteristics of our species in general, rather than variability within and between contemporary populations. We use an evolutionary framework to explore how physical and demographic characteristics of mothers shape the risks of childbirth complications in rural lowland Nepal, where childbearing typically commences in adolescence and chronic undernutrition is widespread, though maternal overweight is increasing in association with nutrition transition.
We conducted secondary analyses of data from a cluster-randomized trial. Women aged 14-35 years were categorized by age, number of previous pregnancies, height, body mass index (BMI), husband's education, and household wealth. Multivariable logistic regression models tested whether these characteristics independently predicted risks of episiotomy and cesarean section (CS, n = 14 261), and obstructed labor (OL, n = 5185).
Risks were greatest among first-time adolescent mothers, though associations with age varied by outcome. Independent of age and parity, short stature and high BMI increased risks of CS and OL, whereas associations were weaker for episiotomy. Male offspring had increased risk of CS and OL but not episiotomy. Wealth was not associated with OL, but lower wealth and lower husband's education were associated with lower likelihood of episiotomy and CS.
At the individual level, the risk childbirth complications is shaped by trade-offs between fertility, growth, and survival. Some biological markers of disadvantage (early childbearing, short stature) increased the risk, whereas low socio-economic status was associated with lower risk, indicating reduced access to relevant facilities. Independent of these associations, maternal age showed complex effects.
人类分娩的进化视角主要集中在我们物种的特征上，而不是当代人群内部和之间的变异性。我们使用进化框架来探讨母亲的身体和人口特征如何影响尼泊尔农村低地分娩并发症的风险，在那里，生育通常在青春期开始，慢性营养不良普遍存在，尽管与营养转型相关的超重现象正在增加。
我们对一项集群随机试验的数据进行了二次分析。将年龄在 14-35 岁之间的妇女按年龄、前次妊娠次数、身高、体重指数（BMI）、丈夫的教育程度和家庭财富进行分类。多变量逻辑回归模型检验了这些特征是否独立预测了会阴切开术和剖宫产（CS，n=14261）以及梗阻性分娩（OL，n=5185）的风险。
首次生育的青少年母亲风险最大，但与年龄的关联因结果而异。不论年龄和产次，身材矮小和 BMI 高均增加 CS 和 OL 的风险，而与会阴切开术的关联较弱。男性后代 CS 和 OL 的风险增加，但会阴切开术的风险不增加。财富与 OL 无关，但财富和丈夫教育程度较低与会阴切开术和 CS 的可能性较低有关。
在个体水平上，分娩并发症的风险是由生育、生长和生存之间的权衡决定的。一些不利的生物学标志物（早育、身材矮小）增加了风险，而较低的社会经济地位则与较低的风险相关，表明获得相关设施的机会减少。独立于这些关联，产妇年龄表现出复杂的影响。
