Higher birth weight may predict better cardiovascular fitness in adulthood, researchers report.
Scientists measured fitness in 286,761 Swedish men ages 17 to 25 by having them ride a bicycle ergometer and recording the wattage they were able to generate. They used data on birth weights from the Swedish Medical Birth Registry.
They found that as birth weight increased, maximum wattage produced increased in direct proportion with it. For each one-fifth of a pound increase in birth weight within the normal range of six to nine pounds, there was a 1.74-watt increase in the energy a man was able to generate. This means that, on average, a man born at 7.6 pounds was able to generate, at maximum effort, 8.7 more watts of energy than one born a pound lighter.
“A higher birth weight means higher cardiovascular fitness,” said the lead author, Viktor H. Ahlqvist, a doctoral student at the Karolinska Institute. “And previous studies have shown that higher cardiovascular fitness implies a lower risk for cardiovascular morbidity and mortality.”
The study, in the Journal of the American Heart Association, controlled for maternal body mass index, maternal age at birth, cesarean section, maternal hypertension and other factors.
“This finding is limited to babies born at full term,” Mr. Ahlqvist said, “so clinicians might want to consider that low birth weight, even in full-term babies, may still be cause for concern.”