Little Legs, Big Impact: Baby's Kicks Pack a Punch

A new study is the first to quantify babies' kick forces in the womb. Above, an animation made from MRI scans showing fetal kicks at various stages of development.

(Image credit: Stefaan W. Verbruggen, et al./Journal of the Royal Society)

Babies aren't so wimpy after all; their kicks in the womb pack about 10 lbs. (4.8 kilograms) of force, according to a new study.

The study, from researchers at Imperial College London, is the first to quantify babies' kick forces in the womb and the amount of stress that moving around puts on the fetal skeleton, the researchers said.

Latest Videos From

Watch full video here:

The study found that the force of the fetal kicks increased during the period between 20 and 30 weeks of gestation. This force went from about 6.5 lbs. (29 Newtons) of force at 20 weeks to 10.5 lbs. (47 Newtons) at 30 weeks. But by 35 weeks, the strength of the fetal kicks had decreased to 3.8 lbs. ( 17 Newtons) of force. This decrease likely occurs because, in late pregnancy, the fetus has less room to move around, the researchers said.

TOPICS

Rachael is a Live Science contributor, and was a former channel editor and senior writer for Live Science between 2010 and 2022. She has a master's degree in journalism from New York University's Science, Health and Environmental Reporting Program. She also holds a B.S. in molecular biology and an M.S. in biology from the University of California, San Diego. Her work has appeared in Scienceline, The Washington Post and Scientific American.