THE EFFECT OF WORK ACTIVITY IN PREGNANCY ON THE RISK OF FETAL GROWTH-RETARDATION

Background. The relationship between physical activity at work and ris k of fetal growth restriction is controversial. For the most part, pre vious studies investigated the effect of work activity on birthweight alone. We evaluated the impact of type of occupation and physical effo rt at work on the risk of ultrasonographically confirmed fetal growth retardation among nulliparous women. Methods. We compared the characte ristics of work and the intensity of occupational fatigue (work postur e, weekly working hours, physical effort at work) in 349 patients with ultrasonographically confirmed fetal growth retardation and 698 contr ol pregnancies with appropriate fetal growth. Physical demands at work were evaluated by interview at birth. Logistic regression analysis wa s used to evaluate the association of employment status, type of occup ation, and intensity of occupational fatigue with the risk of fetal gr owth retardation, correcting for potential confounders (maternal age, pre-pregnancy body mass index, mean weight gain in pregnancy, educatio n, partner's social status, smoking in pregnancy, alcohol use, illicit drug use, time of stopping work, and hypertension). Results. After ad justing for confounding, the risk of fetal growth retardation was simi lar between unemployed and formally employed women at the beginning of pregnancy (OR=1.26; 95% confidence interval=0.86-1.83). However, manu al workers were at slightly higher risk of IUGR than not formally empl oyed women (OR=1.81; 95% CI=1.15-2.85). Among formally employed women, standing or walking at work, and working greater than or equal to 30 hours a week were not significantly associated with IUGR. Finally, the risk of IUGR was significantly higher (OR=2.4; 95% CI=1.36-4.21) amon g women reporting moderate-to-heavy as compared to light physical effo rt at work. Conclusion. Formal employment at the beginning of pregnanc y is not associated with an increased risk of IUGR. However, moderate- to-heavy physical effort at work seems to increase the risk of sonogra phically confirmed fetal growth retardation.