Maternal cigarette smoking and the associated risk of having a child with orofacial clefts in China: A case–control study

BackgroundWe investigated whether maternal and paternal cigarette smoking during early pregnancy could increase the risk of delivering an infant with an orofacial cleft.MethodsA case–control study was carried out in China. 304 infants born with an isolated nonsyndromic oral cleft and 453 non-malformed controls were recruited as participants and their exposure to smoke plus family history data were collected.ResultsThe relative odds ratios of maternal smoking to cause an orofacial cleft in infant increased for 3.30 (95% CI, 1.17–9.33) in CLO and 3.12 (95% CI, 1.24–7.84) in CLP from 1 to 10 cigarettes per day before pregnancy. The unadjusted odds ratio is 3.64 (95% CI, 1.01–13.19) and the adjusted OR is 7.00 (95% CI, 1.44–34.13) in CLO from 1 to 10 cigarettes during the first trimester. Paternal smoking in the periconceptional period was strongly associated with all subtypes of CLP. The association with medium ETS (2–6 h) at home or at work was strongest for infants with all OFCs in the periconceptional period from 1 month before pregnancy through the end of the first trimester.ConclusionThis study confirmed the modest association between maternal smoking and orofacial clefts.