The first findings to result from a collaboration between Seattle Children’s Research
Institute and Microsoft data scientists provides expecting mothers new
information about how smoking before and during pregnancy contributes to the
risk of an infant dying suddenly and unexpectedly before their first birthday.
According to the study published in Pediatrics, any amount of smoking during
pregnancy – even just one cigarette a day – doubles the risk of an infant dying
from sudden unexpected infant death (SUID). For women who smoked an average of
1-20 cigarettes a day, the odds of SUID increased by 0.07 with each additional
“With this information, doctors can better counsel
pregnant women about their smoking habits, knowing that the number of
cigarettes smoked daily during pregnancy significantly impacts the risk for
SUID,” said Dr. Tatiana Anderson, a researcher in Seattle Children’s
Center for Integrative Brain Research and lead author on the study.
“Similar to public health campaigns that educated parents about the
importance of infant sleep position, leading to a 50% decrease in sudden infant
death syndrome (SIDS) rates, we hope advising women about this risk will result
in less babies dying from these tragic causes.”
If no women smoked during pregnancy, Anderson and her
co-authors estimate that 800 of the approximately 3700 deaths from SUID every
year in the US could be prevented, lowering current SUID rates by 22%.
To better understand how smoking contributed to SUID risk,
the researchers used computational modeling techniques to analyse maternal
cigarette smoking habits for all US live births from 2007 to 2011.
Of the about 20 million live births included in their
analysis, over 19 000 deaths were attributed to SUID with the specific cause of
death occurring from SIDS, an ill-defined and unknown cause, or accidental
suffocation and strangulation in bed.
Beyond overall cigarette consumption, the researchers also
looked at how smoking before pregnancy, and cutting back or quitting smoking
during pregnancy, affected SUID risk.
Compared to the over half of pregnant smokers who did not
reduce their smoking during pregnancy, women who reduced cigarette consumption
by the third trimester saw a 12% decrease in SUID risk. Successfully quitting smoking
was associated with a 23% reduction in risk.
Their analysis also showed that mothers who smoked three
months before pregnancy and quit in the first trimester still incurred a higher
risk of SUID compared to non-smokers.
Anderson says the data from this study supports efforts
aimed at encouraging women to quit smoking well before pregnancy.
“The most important takeaway is for women to understand
that quitting smoking before and during pregnancy by far results in the
greatest reduction in SUID risk,” she said. “For pregnant women
unable to quit entirely, every cigarette they can eliminate will reduce the
odds of their child dying suddenly and unexpectedly from SUID.”
TM, et al. Maternal Smoking Before and During Pregnancy and the Risk of Sudden
Unexpected Infant Death. Pediatrics, March 2019.