A team of California and Ohio scientists said today that maternal exposure to cigarette smoke is associated with a doubled risk of a rare but "devastating" condition called persistent pulmonary hypertension of the newborn, in which infants starve for oxygen because blood is not pumped through the lungs to the body.
In persistent pulmonary hypertension of the newborn, or PPHN, the newborn baby’s blood continues to flow as it did when the fetal lungs were not functioning and life-giving oxygen was derived from the mother, through the placenta. Without medical help, which may include a heart-lung bypass, the infant may die.
The scientists reported their findings today in the National Institute of Environmental Health Sciences’ journal Environmental Health Perspectives. The study, supported in part by the National Institutes of Health, was conducted at Children’s Hospital Oakland, in California, to which more than 30 infants with the condition were referred over 18 months. The work was carried out by pediatrician Cynthia Bearer, M.D., Ph.D., of Case Western Reserve University, Cleveland, Ohio, and other scientists there and at the Children’s Hospital Oakland Research Institute.
They said 27.3 percent of the mothers of children with PPHN reported they had smoked during pregnancy, compared to 14 percent of the mothers of normal controls. The non-smokers were asked about passive smoke exposure. Additionally, the infants’ blood samples were tested for a nicotine break-down product called cotinine.
Cotinine was detected in 50 percent of the PPHN infants born to non-smoking mothers, compared to only 18 percent of the normal controls. The levels of cotinine were also significantly higher in the PPHN infants.
Two non-smoking mothers who reported no exposure to passive smoke nevertheless had high cotinine levels. Dr. Bearer -- currently on maternity leave herself -- speculated that the passive smoking may have seemed so ordinary -- or distant -- to these women that it did not "register."
She said that, although PPHN occurs only 1.9 times per 1,000 births, "our study is another good reason that young women should not smoke. We encourage pregnant women not only to cease smoking but to avoid exposure to second-hand tobacco smoke."
The other authors of the study are Renee K. Emerson of Children’s, Mary Ann O’Riordan, Case, and Esther Roltman and Cedric Shackleton, Ph.D., Children’s. They also quizzed the mothers about their exposure to caffeine, vitamins, antacids, pain-killers, antibiotics, alcohol, cocaine and opiates such as heroin -- with no significant variations turning up. However, seven mothers who gave birth to children with PPHN had taken prescription antinausea medications such as Compazine and Phenergan while there was no such use among the mothers of non-PPHN infants. The authors said the use of these drugs should be studied in future studies to discover their "possible role."
Dr. Bearer can be contacted at (216) 321-6943. The full text of the research report will be faxed to reporters calling 919/541-3665 or 919/541-1402.
Also available from today’s issue:
The February 1997 journal, which was unavoidably delayed until today, also contains a commentary on narrowing the scope of studies of endocrine-disrupting chemicals; and a news report on underrepresented minorities in science and engineering, and what’s being done about it at the National Institutes of Health.