Just a cigarette a day in pregnancy doubles Sudden Infant Death risk

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PregnantSmoking any cigarettes – even only one a day – during pregnancy more than doubles the risk of unexpected sudden infant death (SUID). Quitting smoking was associated with a 23% reduced risk.

IFL Science reports that women smoking an average of between one and 20 cigarettes a day increase the odds by 0.07 with each cigarette smoked – but even women who smoked before their pregnancy saw an increased risk in their child dying from sudden unexpected infant death (SUID) – an unexplainable death of an otherwise healthy baby less than a year old.

The report says to understand how SUID deaths relate to maternal cigarette use, researchers analysed data collected by the US Centres for Disease Control and Prevention on smoking habits in pregnant women who had given birth between 2007 and 2011. Of the 20m live births collected in the data set, just over 19,000 were attributed to SUIDS or associated accidental suffocation or strangulation while asleep.

Women who cut back on smoking by the third semester saw a 12% decrease in risk, while those who successfully quit were associated with a 23% reduced risk. On the other hand, mothers who smoked three months before getting pregnant but quit in the first trimester still had a higher risk of SUID when compared to non-smokers.

Two different computational models plot the rate of SUID given the average daily number of reported cigarettes smoked by the mother across all 3 trimesters.

“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,” said lead study author Tatiana Anderson is quoted in the report as saying. “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.”

Though the authors note their study is limited to “conservative smoking estimates” because their data set does not include environmental smoke exposure during pregnancy or postpartum, including fathers who smoke, they affirm that maternal smoking has been linked to premature deaths in infants. In fact, some studies have shown that smoking is the “strongest prenatal modifiable risk factor for SIDS in industrialised nations,” according to the study.

“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 Anderson in the reprot. “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.”

Abstract
Objectives: Maternal smoking during pregnancy is an established risk factor for sudden unexpected infant death (SUID). Here, we aim to investigate the effects of maternal prepregnancy smoking, reduction during pregnancy, and smoking during pregnancy on SUID rates.
Methods: We analyzed the Centers for Disease Control and Prevention Birth Cohort Linked Birth/Infant Death Data Set (2007–2011: 20 685 463 births and 19 127 SUIDs). SUID was defined as deaths at <1 year of age with International Classification of Diseases, 10th Revision codes R95 (sudden infant death syndrome), R99 (ill-defined or unknown cause), or W75 (accidental suffocation or strangulation in bed).
Results: SUID risk more than doubled (adjusted odds ratio [aOR] = 2.44; 95% confidence interval [CI] 2.31–2.57) with any maternal smoking during pregnancy and increased twofold between no smoking and smoking 1 cigarette daily throughout pregnancy. For 1 to 20 cigarettes per day, the probability of SUID increased linearly, with each additional cigarette smoked per day increasing the odds by 0.07 from 1 to 20 cigarettes; beyond 20 cigarettes, the relationship plateaued. Mothers who quit or reduced their smoking decreased their odds compared with those who continued smoking (reduced: aOR = 0.88, 95% CI 0.79–0.98; quit: aOR = 0.77, 95% CI 0.67–0.87). If we assume causality, 22% of SUIDs in the United States can be directly attributed to maternal smoking during pregnancy.
Conclusions: These data support the need for smoking cessation before pregnancy. If no women smoked in pregnancy, SUID rates in the United States could be reduced substantially.

Authors
Tatiana M Anderson, Juan M Lavista Ferres, Shirley You Ren, Rachel Y Moon, Richard D Goldstein, Jan-Marino Ramirez, Edwin A Mitchell

IFL Science report
Pediatrics abstract


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