Background and purpose: People who had low birth weight are at increased risk of stroke. Little is known about the effects of early postnatal growth on stroke risk.
Methods: We followed-up 12 439 people born in Helsinki during 1934 to 1944. Their body size was measured at birth and, on average, 9 times between birth and age 2 years; 507 of them were hospitalized with stroke or died from the disease.
Results: Hazard ratios for stroke declined progressively with increasing gain in weight between birth and age 2 years. The hazard ratio was 0.85 (95% CI, 0.78 to 0.93; P=0.0004) per standard deviation increase in the difference between the weight attained at age 2 years and that predicted from birth weight. A 1-standard deviation increase in body mass index at 2 years of age was associated with a hazard ratio for stroke of 0.84 (95% CI, 0.77 to 0.92; P=0.0002). This association was little changed by adjustment for measures of socio-economic status. Change in body size after the age of 2 years had little effect on the risk of later stroke. People whose mothers had a small external conjugate diameter of the pelvis had an increased risk of stroke. The hazard ratio associated with a diameter of < or =18 cm was 1.62 (95% CI, 1.30 to 2.02; P<0.0001).
Conclusions: Thinness during infancy is associated with an increased risk of stroke in later life. This association may be the result of maternal influences which originated in the mother's infancy when her pelvic shape was established.