Association between maternal occupation as a cleaner/maid/janitor during early pregnancy and selected birth defects in the National Birth Defects Prevention Study

Objectives Cleaning work involves potential exposures to physical, chemical, biological and psychosocial hazards, which might increase the risk of birth defects. Yet, there is limited research focused on maternal occupation in cleaning jobs and the risk of birth defects. We investigated the association between maternal occupation in cleaning-related jobs during early pregnancy and selected birth defects in the National Birth Defects Prevention Study, a case–control study from 1997 to 2011. Methods Mothers self-reported job details, which were classified by occupational epidemiologists into cleaner or non-cleaner occupations. Cases were live births or stillbirths with at least one of 19 eligible birth defects ascertained from state surveillance systems, while controls were randomly selected live births without structural defects. We estimated adjusted ORs with 95% CIs from multivariable logistic regression for associations between maternal cleaning occupations and birth defects, controlling for eight covariates identified a priori. Results Of the 28936 mothers, 1109 (868 cases/241 controls) were assigned a primary occupational code as a cleaner during early pregnancy. In total, 9 of the 19 included birth defects had elevated ORs (>1.5), ranging from 1.58 for anophthalmia/microphthalmia to 2.65 for oesophageal atresia/stenosis; six had CIs that excluded the null (anencephaly, glaucoma, anotia/microtia, cleft lip and palate, oesophageal atresia/stenosis, small intestinal atresia/stenosis). Conclusions We observed that maternal occupation in cleaning-related jobs was associated with several specific birth defects in various body systems. Future studies should explore specific chemical and physical exposures under these cleaning occupations and the association with birth defects.