Women who smoke during pregnancy double the risk their infants will die suddenly, according to a new study.
Researchers estimate about 800 fewer infants would die each year if their mothers hadn’t smoked. That represents about 22% of the 3,700 infants who die annually of sudden unexpected death (SUID), which includes sudden infant death syndrome (SIDS), accidental suffocation/strangulation in bed and unknown causes.
Smoking during pregnancy already has been linked to serotonin abnormalities in infants’ brains and to SIDS. However, researchers wanted to look more closely at the impacts of smoking before and during pregnancy in varying amounts.
They analyzed data on 20.7 million births and just over 19,000 SUID deaths from the Centers for Disease Control and Prevention’s (CDC’s) Cohort Linked Birth/Infant Death dataset from 2007-’11. They reported their findings in “Maternal Smoking Before and During Pregnancy and the Risk of Sudden Unexpected Infant Death” (Anderson TM, et al. Pediatrics. March 11, 2019, https://doi.org/10.1542/peds.2018-3325).
In the months leading up to pregnancy, about 11.5% of women smoked, according to 2011 data. About 9% smoked during pregnancy, and 24% of smokers quit before they became pregnant.
Data showed SUID risk more than doubled when the mother smoked during pregnancy, and there was risk with smoking in any trimester.
The more cigarettes a woman smoked, the greater the risk of SUID for her child. The risk decreased if mothers quit or cut back, according to the study.
Analysis also showed those who smoked only in the months before and not during pregnancy had a higher risk of SUID compared to those who didn’t smoke at all. Some women may have been smoking before realizing they were pregnant or may have returned to smoking after the baby was born. Their partner also may have been smoking, according to the study.
Authors said the nature of the relationship indicates smoking is a cause of SUID.
“Educational efforts to decrease SUID risks should strongly encourage nonsmoking practices before pregnancy and smoking cessation during pregnancy,” they wrote. “Those who are unable to quit entirely should be advised to reduce the amount smoked. We estimate that US SUID rates could be reduced by 22% if no women smoked during pregnancy.”
