Feasibility of maternity protection in early pregnancy.

Many countries have maternity protection laws for women who need job modification or medical leave during pregnancy. This approach will prevent birth defects only if maternal job changes can be made before the critical period of organogenesis, which begins at three weeks' gestation. The authors studied the gestational ages at which pregnant women working with chemicals, radiation, and noise presented for occupational safety and health consultations. The work setting promoted early presentation because the consultation was free, convenient, mandatory, and would not result in job loss. Among the 213 pregnant women evaluated between 1996 and 2000, most (89.5%) had their occupational safety evaluations in the first trimester. Although this sounds ideal, the mean gestational age at presentation was 7.5 weeks, and only 3.3% of occupational health evaluations were initiated by three weeks' gestation. Environmental and biological monitoring showed that none of the women was exposed over occupational limits. These data suggest that a workplace free from reproductive hazards needs to be provided before conception.