Smoking during pregnancy causes respiratory problems in offspring

Robin Wulffson MD's picture
pregnancy, smoking, respiratory problems, bronchiolitis, breathing asistance
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Another impact of maternal smoking on offspring has emerged. A new study evaluated the incidence of bronchiolitis (inflammation of the smaller breathing tubes in the lungs) in infants born to mothers who smoked during their pregnancy.

Researchers affiliated with Harvard Medical School, Baylor College of Medicine, the University of Louisville, and the University of Pittsburgh published their findings online in the journal Pediatrics.

The researchers designed a study to identify factors associated with continuous positive airway pressure (CPAP) and/or intubation for children with bronchiolitis. They conducted a 16-center, prospective study of hospitalized children aged less than two years with bronchiolitis. For three consecutive years from November 1 2007 until March 2010, the investigators collected clinical data and a nasopharyngeal aspirate from the children. They oversampled children from the intensive care unit (ICU); samples of nasopharyngeal aspirate were tested by polymerase chain reaction for 18 pathogens.

The study group was comprised of 2,207 children; 379 (17%) were admitted to the ICU, and 161 (42%) of those children required continuous positive airway pressure (CPAP) and/or intubation; 59 (37%) required CPAP, 64 (40%) required intubation, and 38 (23%) required both. The median age of the subjects was four months; 59% were male; 61% were Caucasian, 24% were black, and 36% were Hispanic. In addition to collecting clinical information, the researchers conducted interviews to obtain patient demographics, medical histories, environmental histories, and acute illness details. The parents were asked if the mother of the child smoked cigarettes during the pregnancy.

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Significant factors for the prediction of CPAP/intubation were: age less than two months (4.3-fold increased risk), maternal smoking during pregnancy (1.4-fold increased risk), birth weight less than 5 pounds (1.7-fold increased risk), breathing difficulty began less than one day before admission (1.6-fold increased risk), presence of apnea (cessation of breathing; 4.8-fold increased risk), inadequate oral intake (2.5-fold increased risk), severe retractions (11.1-fold increased risk), and room air oxygen saturation less than 85% (3.3-fold increased risk).

The authors concluded that they had identified several demographic, historical, and clinical factors that predicted the use of CPAP and/or intubation, including children born to mothers who smoked during pregnancy. They also identified a unique subgroup of children who required mechanical respiratory support less than one day after respiratory symptoms began.

Take home message:
Previous studies have reported that mothers who smoke during pregnancy have children with impaired lung capacity at birth, which continues into childhood. However, this study notes that smoking during pregnancy is an independent risk factor for bronchiolitis requiring CPAP and/or intubation even after controlling for nine other factors. Obviously, women who smoke during pregnancy usually continue to smoke after their child is born. Other members of the household may also be smokers. Thus, many of these children are exposed to second hand smoke, which increases the risk of respiratory problems such as bronchiolitis and asthma. Smoking during pregnancy and exposing children to second hand smoke is a form of child abuse.

Reference: Pediatrics

See also:
Are you at risk for a preterm birth?
Screening for smoking may reveal substance abuse during pregnancy
Drug addicted newborns: a national disgrace
Preventing substance abuse in pregnancy: a successful program

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