Women who suffer work stress during early pregnancy may face greater risk of giving birth to underweight babies, a new study shows.

A work week of 32 hours or more and high job strain during the first trimester had an impact on an infant's birth weight, according to the study conducted by Dutch researchers.

A combination of high job stress and a long work week was associated with the greatest birth-weight reduction and the highest risk of delivering a small-for-gestational-age baby, said the study appearing Thursday in the online issue of the American Journal of Public Health.

The study analyzed responses from 8,266 pregnant women who filled out a questionnaire on employment and working conditions.

"Although pregnant women typically reduce their working hours or workloads at the end of the pregnancy, our results suggest that reducing job strain and working hours in the initial stages of pregnancy may be beneficial among women with stressful full-time jobs," the researchers concluded.

Earlier studies show that women who suffer stress during pregnancy transmit their anxiety to their unborn child from as early as 17 weeks.

Stress levels in foetuses only four months old -- about the time the pregnancy starts to show -- rise and fall in line with those of their mothers', according to earlier studies.

(Xinhua News Agency June 19, 2009)