Organic Solvent Exposure During Pregnancy and Congenital Malformations

To the Editor: Dr Khattak and colleagues¹ present a study on the relationship between gestational exposure to organic solvents and the incidence of major congenital malformations, as well as other outcomes such as miscarriage. Significantly more major malformations were found in the cases than in the controls (odds ratio, 13; 95% confidence interval, 1.8-99.5). The rates of miscarriage during the study period were not different between the cases and controls, yet the prevalence of miscarriage prior to the study period was much higher in the cases than in the controls (51% vs 19.7%). This difference raises questions about the comparability of the groups; perhaps a substantial proportion of previous miscarriages were also due to solvents. This unusual finding is difficult to explain given that other risk factors for repeated miscarriages (eg, antiphospholipid syndrome, shift work) were not reported. Because women with a previous miscarriage are more likely to have children with congenital malformations,² the association between solvent exposure and major congenital malformations may have been confounded.