Secondhand smoke during the periconceptional period increases the risk for orofacial clefts in offspring

Abstract

Maternal SHS exposure during the periconceptional period increases the risk for OFCs in offspring among nonsmoking mothers.

Second‐hand smoke exposure and orofacial clefts

“…In this issue of Paediatric and Perinatal Epidemiology , Pi et al report data on the association of exposure to SHS during the periconceptual period (1 month before to 2 months after conception) among non‐smoking women with an orofacial cleft (OFC) affected pregnancy (240 women and 1420 women with a non‐OFC affected pregnancy). The study was based on data collected in a population‐based case‐control study in a rural part of northern China during 2002‐16.…”

“…When the data were adjusted for maternal fever/flu, infant sex, a history of a pregnancy previously affected by a congenital anomaly and farming occupation, the association remained the same. Importantly from a biological plausibility perspective, this study considered whether there was a dose‐response effect; frequent SHS exposure, defined as more than 6 times per week, was associated with a higher risk of OFCs (OR 2.6 [1.8, 3.8]) and CL ± P (OR 2.5 [1.7, 3.7]) than exposure to SHS 1‐6 times a week …”

“…Studies investigating risk factors for congenital anomalies are challenging as these are rare events which are often poorly recorded. The study by Pi and colleagues has several strengths, including the study comprised of women who were non‐smokers; cases were confirmed (using physical examination, ultrasound examination results and photographs with consent); data were collected by trained health care workers through face‐to‐face interviews; interviewers helped confirm the exposure period with the mother; cases were matched to controls; and there were low levels of missing data for key variables. However, there are also some limitations.…”

“…Smoking status was obtained through self‐report; it is not clear if syndromic OFCs were included in the analysis; whether questionnaire data from women who did not participate as they refused to provide biological samples were included and, as the authors acknowledge, it is not possible to rule out confounding from unmeasured factors. Finally, Pi and colleagues were unable to undertake adjusted analysis of cases with cleft palate, an OFC subtype, due to the small sample size.…”

“…So, what does the work of Pi and colleagues mean for research and practice? While this study adds to the growing body of evidence that exposure to SHS increases the risk of a pregnancy being affected by a congenital anomaly, further research is needed which specifically addresses the limitations in this study and, in particular, the lack of a sufficient sample which is a common limitation in studies of congenital anomalies.…”