Smoking during pregnancy doubles the risk of sudden unexpected infant death, according to a new study that analysed over 20 million births.
The research, published in the journal Pediatrics found that for women who smoked an average of 1-20 cigarettes a day, the odds of SUID increased by 0.07 with each additional cigarette smoked. SUID includes sudden infant death syndrome (SIDS), accidental suffocation/strangulation in bed and death from unknown causes.
"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 lead author Dr Tatiana Anderson of Seattle Children's Center for Integrative Brain Research.
"Similar to public health campaigns that educated parents about the importance of infant sleep position, leading to a 50 per cent 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."
As part of the study, Dr Anderson and her colleagues analysed 20.7 million births and 19,000 cases of SUID. As well as cigarette consumption, the team also examined how smoking before pregnancy, a well as reducing or quitting smoking during pregnancy affected SUID risk.
Of the mums who smoked while expecting, 55 per cent did not reduce the number of cigarettes smoked, 20 per cent quit at the beginning of the third trimester while 24 per cent cut down.
And the results were clear.
Women who reduced their smoking by the third trimester decreased the risk of SUID by 12 per cent. And those who ditched the habit entirely saw the risk reduce by 23 per cent. "Assuming causality, an estimated 800 infants per year, or 22 per cent of all SUID cases in the United States, were attributed to maternal smoking during pregnancy," the authors write.
Adds Dr Anderson, "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."
But cutting back helps, too.
"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," she says.
While the study uses US data, last year a report from the Australian Institute of Health and Welfare (AIHW) highlighted that around one in 10 Australian women continue to smoke during the first 20 weeks of their pregnancy, down from 12.9 per cent in 2011.
According to Hilary Rorison, Midwifery Advisor from the Australian College of Midwives, "This research confirms the importance of supporting women in the reduction, and ideally cessation, of smoking in pregnancy." And, according to Mrs Rorison, women need non-judgemental support and information to assist them to do so.
"A known midwife providing care from conception through to six weeks postnatally, can provide ongoing personalised support for these women," she says. "ACM also encourages women to discuss their smoking status with their GP prior to becoming pregnant if possible. There are many services available to women to assist them in smoking reduction and cessation including the Quit for 2 App."
Red Nose Australia recommends a smoke free environment both before and after birth adding that paternal smoking also increases the risk of SUDI.
"Babies who are exposed to tobacco smoke before and after birth are at an increased risk of SUDI," the organisation says. "To avoid exposing your baby to tobacco smoke, don't let anyone smoke near your baby - not in the house, the car or anywhere else your baby spends time."
Find more information about the Quit for 2 App here.