Risk of adverse pregnancy outcome in women exposed to livestock: a study within the Danish National Birth Cohort

Maternal infection in pregnancy is a known risk factor for adverse pregnancy outcome, and a number of zoonotic pathogens may constitute a risk to pregnant women and their fetuses. With animal contact as a proxy for the risk of zoonotic infection, this study aimed to evaluate pregnancy outcome in women with self-reported occupational or domestic contact with livestock compared to pregnant women without such contact. The Danish National Birth Cohort collected information on pregnancy outcome from 100 418 pregnant women (1996–2002) from which three study populations with occupational and/or domestic exposure to livestock and a reference group of women with no animal contact was sampled. Outcome measures were miscarriage, very preterm birth (before gestational week 32), preterm birth (before 37 gestational weeks), small for gestational age (SGA), and perinatal death. Adverse reproductive outcomes were assessed in four different exposure groups of women with occupational or domestic exposure to livestock with no association found between exposure to livestock and miscarriage, preterm birth, SGA or perinatal death. These findings should diminish general occupational health concerns for pregnant women with exposures to a range of different farm animals.