[Epidemiological studies on the outcome of pregnancy and delivery of the female employees].

Little information exists about the effect of working during pregnancy on pregnancy outcome. In order to determine whether pregnancy outcome was altered when women were employed outside their homes, pregnancy outcomes of 4,395 working women were compared with outcomes of 10,203 women (control) who were not employed. The pregnancy outcomes of working women were also analysed according to the occupation and working hours. Irregularity of the menstrual cycles prior to the pregnancy was observed more frequently in the working women than control (19.5% vs 14.9%, p less than 0.001). There were significant differences between the employees and control in rates of spontaneous abortion and premature delivery (6.8% vs 5.4%, p less than 0.01), spontaneous vaginal delivery (80.7% vs 84.5%, p less than 0.001), small-for-gestational age infant (SGA) (4.6% vs 3.4%, p less than 0.001), and fetal distress (7.6% vs 6.5%, p less than 0.02). However, no statistical differences were noted in rates of EPH gestosis, gestational anemia, neonatal hyperbilirubinemia, perinatal death, or malformation prevalence. Among the 1,888 employees, rates of threatened abortion and threatened premature delivery, and spontaneous abortion and preterm delivery were significantly higher in the working women whose actual work were longer than eight hours per day than those with a shorter work; that is 13.7% vs 10.4% (p less than 0.05) and 9.3% vs 6.1% (p less than 0.02), respectively. Overall the results are reassuring that working during pregnancy is in itself a risk factor for adverse outcome.