High Fetal CO Exposure May Up Gastroschisis Risk


ST. PETE BEACH, FLA. — Young pregnant women who smoke cigarettes or marijuana or who are malnourished have a significantly increased risk of having an infant with gastroschisis, a case-control study suggests.

Those who have both risk factors have an even greater risk of having an infant with this severe birth defect, Phung Kim Lam, Ph.D., reported at the annual meeting of the Teratology Society.

Dr. Lam studied 55 infants with gastroschisis and 94 age-matched controls. Maternal information was based on interviews and food-frequency questionnaires.

Mothers were said to have high carbon monoxide (CO) exposure if they smoked at least one pack of cigarettes daily near the time of conception or if they smoked marijuana habitually around that time, said Dr. Lam of the University of California, San Diego.

Malnutrition was characterized by protein intake of less than 72 g/day, zinc intake of less than 10 mg/day, and maternal body mass index of less than 22 kg/m2; these three factors were highly correlated (low zinc with low protein, and low protein with BMI). They are also correlated with numerous other markers of nutritional status, such as intake of certain other vitamins and minerals.

On multiple conditional logistic regression, gastroschisis was associated with high CO exposure (odds ratio 2.64) and low animal protein intake (OR 2.45).

Young mothers without low BMI but with high CO exposure were more likely than controls to have a baby with gastroschisis (odds ratio 16.81), as were those with low BMI and no CO exposure (OR 19.69). But the finding was much more marked in those with low BMI and high CO exposure, compared with controls (OR 26.49), she said.

The findings support those of an animal model in which exposure to high levels of carbon monoxide and low protein and zinc intake in pregnant mice led to this birth defect.

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