A nested case-control study of low birthweight among cosmetologists

This study was designed to determine whether licensed female cosmetologists with a low birthweight child were more likely to perform specific occupational tasks during pregnancy than cosmetologists who had a normal weight child. We also investigated certain salon characteristics in relation to low birthweight status. This nested case-control study followed-up a positive association of low birthweight children among cosmetologists found in a retrospective cohort study previously reported. Cases were cosmetologists with children born between 1997 and 2003 weighing < 2,500 g, selected from the retrospective cohort study. Controls were cosmetologists with full-term children who weighed > 2,500 grams at birth, frequency matched on year of birth of the child. A mailed questionnaire gathered information on potential confounders and detailed exposure information about work environment and occupational tasks of cosmetologists. Frequency of product use was dichotomized into daily/less than daily for each task. Number of hours worked per week was also considered. Birth certificate data were used for information on some potential confounders and birthweight. Using logistic regression, adjusted odds ratios (OR) and 95% confidence intervals (95% CI) were obtained. A total of 125 (30%) cases and 158 (35%) controls agreed to participate. Responders and non-responders were similar on birthweight and most demographic characteristics. None of the specific cosmetology tasks studied were associated with low birthweight. Working in a salon located in a house/building with other businesses was associated with having a low birthweight child [OR = 2.20, 95% CI (1.21, 4.02)]. We did not find any associations between specific tasks of cosmetologists and low birthweight.