OBJECTIVES: Morphological differences between parous and nulliparous women have long been interpreted as reproductive signatures. However, such patterns may instead reflect demographic composition. This study aimed to reassess parity-related morphological variation by reducing confounding from age and BMI using propensity score matching (PSM). METHODS: Anthropometric data from 1339 Korean women aged 20-39 years were analyzed. Forty-five direct and derived body dimensions, collected following ISO 7250-1:2017, were compared between parous and nulliparous women before and after 1:1 nearest-neighbor PSM on age and BMI. Group differences were examined for torso breadths, depths, circumferences, and proportional indices. RESULTS: Unadjusted analyses reproduced well-known findings: parous women showed greater abdominal breadths and depths, larger circumferences, and adiposity patterns commonly attributed to childbirth. After PSM, however, most differences-including widely cited markers of lower-body enlargement and postpartum contour change-were substantially attenuated or statistically nonsignificant. Only a small number of proportional indices (e.g., underbust/weight, waist/weight, elbow/weight) retained modest differences, indicating that parity leaves limited, anatomically localized morphological signatures rather than broad structural changes. CONCLUSIONS: Demographic composition, rather than reproductive biology alone, accounts for much of the observed variation in cross-sectional datasets. Matching-based approaches clarify the independent contribution of parity, strengthen causal inference in anthropometric research, and underscore the need to consider population structure when interpreting life-history-related variation in adult female morphology.
Lee et al. (Fri,) studied this question.