A group of medical experts said Monday it has found that smoking during pregnancy can trigger muscular contractions in the uterus that can lead to miscarriages and premature births, although the exact mechanism is still under research.
In an experiment in which pregnant lab rats were made to inhale smoke from the equivalent of seven cigarettes per day for three days, the contraction response by the uterus muscles to hormones that induce contractions was more than double that of a control group not exposed to smoke.
The experts, who announced the findings at a meeting of the Japan Society of Obstetrics and Gynecology in Fukuoka, said they believe smoking raises the muscles' sensitivity toward the hormone.
It is unclear what substance in tobacco is responsible for the results, but the group said it will research whether there is a link with nicotine.