Introduction Nail technicians and hairdressers may be exposed to products containing chemicals with potential reproductive effects. While studies have examined birth defects in children of cosmetologists and hairdressers, nail technician work has not been individually evaluated as a risk factor for birth defects.

Objectives We investigated associations between maternal occupation as a nail technician or hairdresser during pregnancy (versus non-cosmetologist) and selected birth defects.

Methods We analyzed population-based case-control data from the multisite National Birth Defects Prevention Study, 1997–2011. Cases were fetuses or infants with major structural birth defects; controls were liveborn infants without major birth defects. For 31,652 case and 11,613 control mothers, expert raters classified self-reported maternal jobs into discrete categories as nail technician, hairdresser, combination nail technician-hairdresser, other cosmetologist, or non-cosmetologist. We used logistic regression to calculate odds ratios (ORs) and 95% confidence intervals (CIs) for associations between occupation during the first trimester of pregnancy and birth defect type, controlling for age, smoking, education, and race/ethnicity.

Results Sixty-one mothers worked as nail technicians, 196 as hairdressers, 39 as combination nail technician-hairdressers, and 42,810 as non-cosmetologists during pregnancy. Strongest associations among nail technicians included multiple congenital heart defect (CHD) groups: any CHD (OR=2.7; CI: 1.3–5.9); conotruncal (OR=3.0; CI: 1.0–8.8) (Tetralogy of Fallot [OR=3.5; CI: 1.0–12.9]); right ventricular outflow tract obstruction (OR=3.2; CI: 1.0–10.4); and septal (OR=3.1; CI: 1.2–8.1). Cleft lip with cleft palate was associated with occupation as a hairdresser (OR=2.0; CI: 1.1–3.7). All oral cleft groups were associated with combination nail technician-hairdresser work (ORs ranging from 4.2 to 5.3).

Conclusion Despite small samples, results suggest associations between maternal nail technician work during pregnancy and various CHDs and similarly between hairdresser work and oral clefts. Future research could aim to identify potential workplace reproductive hazards and interventions in these occupations.