First-trimester occupational exposures and hypertensive disorders of pregnancy among US nurses.

ABSTRACT

BACKGROUND: Limited and conflicting data exist regarding the impact of first-trimester nursing occupational exposures on hypertensive disorders of pregnancy (HDP). AIMS: To investigate whether first-trimester night shift work, work hours and work-related activities are associated with HDP. METHODS: We conducted a cross-sectional analysis of 6610 women within the Nurses' Health Study II. We used multiple logistic regression to estimate the odds ratios (ORs) and 95% confidence intervals (CIs) for the relation of occupational exposures to HDP. RESULTS: Nine per cent of respondents reported an HDP in the index pregnancy (gestational hypertension n = 354, 5%, preeclampsia n = 222, 3%). First-trimester fixed or rotating night shift work was not significantly associated with gestational hypertension or preeclampsia compared to day shift work only. Compared to those working 21-40 h/week, working overtime (≥41 h/week) was not associated with gestational hypertension but was associated with 43% higher odds of preeclampsia (95% CI 1.02, 2.00). For part-time work (≤20 h/week), the OR was 0.76 (95% CI 0.56, 1.02) for gestational hypertension and 0.64 (95% CI 0.43, 0.97) for preeclampsia. The odds of preeclampsia were 3% higher per additional hour worked per week (95% CI 1.01-1.04). Compared to 0-4 h spent standing or walking per day, standing or walking ≥9 h daily was associated with 32% lower odds of gestational hypertension (95% CI 0.47, 0.99) but was not significantly associated with preeclampsia. Frequency of heavy lifting was not associated with either hypertensive disorder or pregnancy. CONCLUSIONS: Among nurses, working overtime was associated with higher odds of preeclampsia.