Early growth, adult income, and risk of stroke

A number of studies have shown that reduced intrauterine growth and low birth weight are associated with raised rates of fatal and nonfatal stroke in adult life. Whether this increased risk of stroke is modified by growth in childhood or by socioeconomic status in adult life is not known.

We studied hospital admissions and deaths from stroke among 3639 men who were born in Helsinki University Central Hospital during 1924 to 1933. They had detailed records of their body size at birth, their growth through childhood, and their social circumstances as adults. Three hundred thirty-one of the men had had a stroke.

Hazard ratios for stroke were related to low birth weight in relation to head circumference (P=0.005) and to short length in relation to head circumference (P=0.02). These associations were stronger for hemorrhagic than for thrombotic stroke. Men who developed stroke still had below-average stature at 7 years (P=0.05), but after 7 years their height "caught up" through accelerated growth. As adults they had low incomes and low social class (P<0.0001).

Stroke may originate through reduced fetal growth, with low body weight and short body length at birth but "sparing" of head growth. Other studies suggest that this pattern of growth is associated with persisting elevation of blood pressure and raised plasma fibrinogen concentrations, 2 known risk factors for stroke. The risk of stroke is increased by accelerated growth in height during childhood. Accelerated growth has previously been linked to the development of hypertension in adult life. Stroke risk is further increased by adverse influences linked to low income.