Smoking Linked to Oral CleftsDec 23, 2008 | Parker Waichman LLP
A new study published in the journal Epidemiology says that smoking during the first trimester of pregnancy is linked with an increased risk of oral clefts in newborns, reports Science Daily. The Mayo Clinic explains that cleft lip and cleft palate are among the most common of birth defects, affecting about one in 700 infants annually in the United States.
The study was based on a larger Norwegian case control study involving researchers from the Norwegian Institute of Public Health, the University of Bergen, Rikshospital, Haukeland University Hospital, and the National Institutes of Health (NIH) in the United States, said Science Daily. Science Daily said the research team wanted to learn if smoking or exposure to passive—second-hand—smoke was involved in oral cleft defects and if genes influence the risk in how toxic chemicals in cigarette smoke are processed.
Of the 676 babies born with oral clefts and referred for cleft surgery in the years between 1996 and 2001, 573 were involved in the study; 763 babies born during the same time frame in Norway were randomly selected as controls, reported Science Daily.
Science Daily explained that an array of blood, PKU, and DNA samples were taken from the children referred for surgery and their parents, as well as children and parents from the control group. When the babies were four weeks old, the mothers completed a questionnaire with information concerning medical conditions and environmental exposure. The survey included specific questions about the mothers' smoking habits and exposure to passive smoking before pregnancy and during the first trimester of pregnancy, said Science Daily.
The researchers found that 42 percent of the mothers who gave birth to babies with oral clefts and 32 percent of the control group mothers reported having had smoked in the first trimester of pregnancy. Also, there was an increased risk (nearly two-fold) for cleft lip, with or without cleft palate if the mother smoked in excess of 10 cigarettes daily and 1.6-fold when the mother was exposed to passive smoke. According to Science Daily, the researchers concluded that 19 percent of Norwegian cleft lip cases might be linked to maternal smoking in the first trimester.
According to The Mayo Clinic, cleft is defined as an opening or split in the upper lip, the roof of the mouth (palate), or both and can affect one or both sides of the upper lip. Under normal circumstances, lip closure occurs about five weeks into pregnancy and is followed by palate closure at week nine.
WebMD notes that oral clefts are treatable birth defects in which the baby's palate does not develop normally during pregnancy, leaving an opening, known as a cleft, that can extend into the nasal cavity. Unless corrected surgically, clefts can “interfere with feeding, speech development, and hearing,” says WebMD, adding that babies whose mothers used certain medicines, were exposed to radiation or infections, took illegal drugs, smoked, or drank alcohol during pregnancy might be at increased risk for the defect.