By David Douglas
NEW YORK (Reuters Health) – Heightened maternal serum levels of paraxanthine, a caffeine metabolite, are associated with small-for-gestational age infants, researchers report in the January 1st issue of the American Journal of Epidemiology. In fact, lead author Dr. Mark. A. Klebanoff told Reuters Health that "this was particularly true if the mother also smoked."
Dr. Klebanoff, at the National Institutes of Health, Bethesda, Maryland, and colleagues sought to determine whether third-trimester serum concentrations of paraxanthine were associated with delivery of small-for-gestational age infants.
The researchers examined serum samples from 2515 women who had given birth during a 7-year study. Of the offspring, 222 were considered to be small-for-gestational age.
Mothers of such small infants had significantly higher (p = 0.02) mean levels of paraxanthine (754 ng/mL) than did the other mothers (653 ng/mL). Furthermore, a trend towards a linear correlation between paraxanthine levels and reduced fetal weight was seen in smokers. There was no such association in nonsmokers.
Allowing for other factors such as maternal weight, ethnicity, and number of cigarettes smoked did not prompt a substantial change in the relationship.
Commenting on these findings Dr. Klebanoff added that "our research shows that increasing maternal exposure to caffeine during pregnancy is associated with reduced growth of the fetus." Most importantly, he added, "our results provide yet another reason for women not to smoke, particularly during pregnancy. Among women who smoke, consuming caffeine may well add to the harm of smoking."