Newborns whose mothers exercise during pregnancy may become physically coordinated a little earlier than other babies, according to a captivating new study of gestation, jogging and the varying ability of tiny infants to make a fist. The study’s findings add to growing evidence that physical activity during pregnancy can strengthen not just the mother but also her unborn children and might influence how well and willingly those children later move on their own.

The current physical activity guidelines in the United States and Europe call for children to run and play for at least an hour every day. But, according to most estimates, barely a third of European and American youngsters are that active. Many factors contribute to this physical languor, including crowded family schedules, lack of physical education programs in schools, childhood obesity and overly ample screen time.

But recently, Linda E. May, an associate professor of foundational science and research at East Carolina University in Greenville, N.C., began to wonder whether the prenatal environment might also play an unexpected role.

Her own earlier research hinted that the idea was plausible. For a 2011 study, she and her colleagues had compared the cardiac function of babies born to mothers who had been sedentary or worked out during pregnancy and found that infants whose mothers exercised developed stronger, more athletic hearts even before birth. Their pulses were slower and the beat-to-beat variability greater, a general indication of better-conditioned cardiac muscles.