Developmental instability (DI) reflects an organism’s inability to develop an ideal phenotype when challenged by genetic and environmental insults. DI can be estimated via the proxy measure of fluctuating asymmetry (FA), i.e., the small random deviations from perfect bilateral symmetry observed in the morphology of paired traits. The mechanisms involved in the genesis of FA in human populations are relatively unknown, though animal research indicates that hormonal processes may be involved. As maternal stress during pregnancy is detrimental to various developmental processes, elevated prenatal cortisol may represent a causal factor in the subsequent emergence of an asymmetrical phenotype. The main purpose of this pre-registered meta-analysis based on three empirical studies was to investigate whether mid-trimester amniotic cortisol levels predict subsequent FA in finger lengths of infants from Germany, Portugal, and the UK. No statistically significant relationships were observed, and meta-analytic combination of the effect size estimates yielded a null result. We did, however, detect significant positive correlations between the cortisol present in the amniotic fluid and maternal plasma in the Portuguese cohort, and observed that FA in the German cohort was significantly lower at 70-months than at either 9- or 20-months. Taken together, the current findings run contrary to animal research showing that elevated prenatal corticosterone exposure leads to increased FA. However, this may be because a single cortisol assay obtained via amniocentesis is an inadequate proxy for average gestational exposure, and/or that prenatal cortisol levels at an earlier (i.e., first rather than second trimester) stage of pregnancy is what explains variance in subsequent FA.

发育不稳定性（DI）反映了生物在受到遗传和环境侵害时无法形成理想的表型。可以通过波动不对称（FA）的代理度量来估计DI，即，在成对性状的形态学中观察到的与完全双侧对称的随机偏差很小。尽管动物研究表明可能涉及激素过程，但人类中FA发生的机制尚不清楚。由于孕妇在怀孕期间的压力不利于各种发育过程，因此产前皮质醇升高可能是随后出现不对称表型的原因。这项基于三项实证研究的预注册荟萃分析的主要目的是调查孕中期羊膜皮质醇水平是否可预测德国，葡萄牙和英国婴儿的手指长继发FA。没有观察到统计学上显着的关系，并且效应大小估计值的荟萃分析组合得出的结果无效。但是，我们确实检测到葡萄牙人群中羊水中存在的皮质醇与母体血浆之间存在显着的正相关性，并且观察到德国人群中的FA在70个月时显着低于9个月或20个月时。综上所述，当前的发现与动物研究相反，动物研究表明，产前皮质酮的暴露增加会导致FA升高。然而，