Firefighter occupational factors and the risk of preterm birth: results from a survey of women firefighters in the USA.

OBJECTIVES: Previous research has suggested that women firefighters may have a greater risk of adverse reproductive outcomes compared with non-firefighting women. In this study, we investigated the association between firefighter occupational factors and risk of preterm birth. METHODS: This cross-sectional analysis of US firefighters surveyed in 2017 compared preterm birth among firefighters to non-firefighters using age-at-pregnancy-standardised prevalence ratios. Generalised estimating equations estimated relative risks and 95% CIs between firefighter occupational factors (career or volunteer, wildland status, shift schedule, fire responses, work restriction) and preterm birth risk. We adjusted for age-at-pregnancy, education, gravidity, BMI, and smoking and considered effect modification by age-at-pregnancy and career versus volunteer status. RESULTS: Among 934 women who reported 1356 live births, 12% were preterm (n=161). Preterm birth prevalence among firefighters was 1.41 times greater than non-firefighters (95% CI 1.18 to 1.68). Among wildland and combination wildland/structural firefighters, volunteers had 2.82 times the risk of preterm birth (95% CI 1.19 to 6.67) compared with career firefighters. Firefighters who started restricting their work in the 2nd trimester had a nonsignificant 0.67 times lower risk of preterm birth than those who started in the 3rd trimester or did not restrict work at all (95% CI 0.43 to 1.03). CONCLUSIONS: Firefighters may have greater risk of preterm birth than non-firefighters, which could be influenced by roles in the fire service and work restrictions taken.