Prenatal smoking, drinking in moms linked to higher SIDS risk: Study

Kids of mothers who both drink and smoke beyond the first trimester of pregnancy may have a 12-fold higher risk for Sudden Infant Death Syndrome (SIDS) compared to those unexposed in the first trimester, a new study says.

SIDS is the sudden, unexplainable death of children under one year of age, explained the researchers, including those from Boston Children's Hospital in the US.

The study, published in the journal Lancet, assessed how SIDS risk is influenced by the timing and amount of prenatal exposure to tobacco and alcohol.

"Ours is the first large-scale prospective study to closely investigate the association between prenatal alcohol and tobacco exposure and the risk of SIDS," said study first author Amy J. Elliott from the Avera Health Center for Pediatric & Community Research in the US.

"Our findings suggest that combined exposures to alcohol and tobacco have a synergistic effect on SIDS risk, given that dual exposure was associated with substantially higher risk than either exposure alone," Elliott explained.

In the study, the researchers followed the outcomes of nearly 12,000 pregnancies among women from two residential areas in Cape Town, South Africa, and five sites in the US from 2007 until 2015.

They determined one-year outcomes for about 94 per cent of the pregnancies, and found that 66 infants died during that time, including 28 SIDS deaths, and 38 deaths from known causes.

The scientists also said the risk of SIDS was increased five-fold in infants whose mothers reported they continued smoking beyond the first trimester.

This risk was four-fold more in infants whose mothers said they continued drinking beyond the first trimester, according to the study.

These were in comparison to children who were either not exposed to tobacco or alcohol during gestation, or whose mothers quit tobacco or alcohol use by the end of the first trimester.

"Our findings support the current recommendation of the US Centers for Disease Control and Prevention (CDC), the US Surgeon General, and the World Health Organization (WHO) that women not drink or smoke during pregnancy, and emphasizes the significance of dual exposure, which provides the greatest risk for infant mortality," said study co-author Hannah C. Kinney from the Boston Children's Hospital.