Reproductive disorders in hairdressers and cosmetologists: a meta-analytical approach

Objectives: To synthesize the epidemiological evidence of the risk of adverse pregnancy outcomes among hairdressers and cosmetologists.
Methods: A systematic literature search up to 1 February 2012 was carried out using major bibliographic databases, grey literature, contact with research teams, review papers and reference list of selected articles. Observational studies reporting measures of effects in relation with body cares (hairdresser, cosmetologist …) and reproductive disorders were included. Study quality has been assessed by three reviewers. The estimated risk ratios (RR) from all studies reporting on identical outcomes were combined using an average of logarithm transformation of estimated RRs and weighted by their inverted variance. Statistical heterogeneity across studies was assessed using the Cochrane Q statistic. To explore the sources of heterogeneity, several sensitivity analyses and subgroup analyses have been conducted to base on quality of study, country, study period, alcohol, smoking, jobs and control populations.
Results: 19 studies have been selected and deeply reviewed. The combined ratio risk (RRc) of five reproductive outcomes were calculated and were significantly increased to four outcomes : time-of-pregnancy with RRc=1.11 [95%CI: 1.03 – 1.19] ; prematurity with RRc=1.05 [95%CI: 0.99 – 1.11]; intrauterine growth retardation with RRc=1.24 [CI95%: 1.10-1.41]; low birth weight with RRc=1.21 [95%IC: 1.06-1.39]; embryonic and fetal losses with RRc=1.19 [95%IC: 1.03 - 1.38].
Conclusions: The job of hairdresser/cosmetologist is associated with a small increase of the risk of some reproductive disorders. But the evidence level is rather weak and the link of causality between job and reproductive outcomes can’t be affirmed. Further studies are needed taking a better account of the variable “alcohol consumption”.