The Multidimensional Influence of Health on Fertility Outcomes for Men: Evidence from Swedish Military Conscription Data

Kieron Barclay , Stockholm University
Martin Kolk, Stockholm University

We examine how multidimensional health in early adulthood predicts men’s later-life fertility using Swedish population registers linked to universal military conscription examinations. Our study follows men born 1951–1979, observed for fertility through 2024, and exploits objective measures taken at ages ~18–20 across twelve indicators: muscular strength (handgrip, arm, leg, composite), cardiovascular health (resting heart rate, blood pressure, ECG pathology, maximal working capacity on cycle ergometer), and blood/urine biomarkers (hematocrit, erythrocyte sedimentation rate, U-glucose, U-albumin). Outcomes are completed parity and childlessness. We estimate linear models for all men and sibling fixed-effects models that compare full brothers, adjusting for birth cohort and age at test. Results show pronounced, monotonic gradients for strength and fitness. Men in the weakest strength deciles or lowest fitness deciles have 0.25–0.45 fewer children and a 10–20 percentage-point higher probability of childlessness than those in the strongest/highest deciles; these differences persist, with moderate attenuation, in sibling fixed-effects. High resting heart rate shows similar but slightly smaller gradients. Blood pressure categories and ECG abnormalities exhibit modest associations. Biomarkers indicative of metabolic and renal stress are consequential: positive U-glucose and U-albumin are associated with ~0.10–0.20 fewer children and ~5 percentage-point higher childlessness. Hematocrit and inflammation show smaller, suggestive, and potentially non-linear patterns. Findings are consistent with multiple channels – physiological fecundity, partner-market dynamics, and socioeconomic mediation – and indicate that early-adult health is an important component of male fertility stratification. Investments in adolescent and young-adult health could therefore have long-run implications for family formation.

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 Presented in Session 1. Flash Session Fertility and Health