STANDING for prolonged periods during pregnancy may curb the growth of the baby in the womb, research suggests.
Pregnant teachers, childcare workers and women that work in sales are among those whose babies are likely to have smaller heads when they are born -- implying a slower growth rate.
The study, published online in Occupational and Environmental Medicine, examined 4,680 mothers-to-be from early pregnancy onwards.
The women were surveyed on their work conditions and the physical demands of their jobs. The progress of their babies was also monitored.
Just under two-fifths of the women spent a long time on their feet at work. These women were likely to have babies whose heads were an average of 1cm smaller than the norm at birth.
Working for long hours also had an affect on foetal growth rate, the study found.
Of those surveyed, around half the women worked between 25 and 39 hours a week, while 23pc worked more than 40 hours a week.
Those who worked more than 40 hours a week had smaller babies than those who worked under 25 hours a week.
But working up to 36 weeks of pregnancy has no adverse impact on foetal development, researchers added.