A new research suggests that 'boring and repetitive' household chores raises the odds of giving birth prematurely.
Exercise, however, is good for both mother and unborn child. Dailymail.co.uk reports that the study involved data collected from almost 12,000 new mothers about how much they had exercised during pregnancy including housework.
The findings showed that mentally unstimulating work, including doing jobs around the house day-in day-out, increased the chances of giving birth at least three weeks early by up to 25 percent.
Although it isn't clear why, researchers think it may be that boring tasks increase levels of stress hormones involved in triggering labour.
The study, published in the journal Perinatal Epidemiology, also threw up some other interesting results. For instance, women who work night shifts seem to have slightly heavier babies.
Again it isn't clear why, but may simply be that those who work through pregnancy are healthier in general.
The study also revealed that sedentary lifestyles raised the odds of having an underweight baby, while light and appropriate workouts did no harm to either mother or baby.
'Pregnancy is not a disease. In fact, most women who are pregnant are healthy and most of them are being delivered of perfectly healthy babies. Women who are healthy and do not have pregnancy complications should not restrict their activities in order to achieve a better pregnancy outcome,' said researcher Hajo Wildschut, of Erasmus University in Rotterdam.
Experts say that in most cases exercise in pregnancy is safe, however, mothers-to-be are advised to avoid sports which needs physical exertion.
'Exercise is good in pregnancy, it keeps you aerobically fit, it keeps your weight under control, it probably reduces the chances of difficulties and it makes it easier to deal with the birth and after wards,' said Patrick O'Brien, a consultant obstetrician at the Royal College of Obstetricians and Gynaecologists.