Placental theophylline transfer in pregnant asthmatics.

The newborn's potential for xanthine toxic reactions from placental transfer of theophylline or caffeine conversion from theophylline was studied in 12 newborns of asthmatic mothers. Our results showed that maternal and cord theophylline levels were not notably different, yet heelstick levels tended to be higher than maternal levels. Newborn heelstick theophylline levels ranged from 2.3 to 19.6 microgram/mL with a mean of 10.5 microgram/mL. No caffeine conversion from theophylline was seen. Heart rate, Apgar scoring, and other parameters were not statistically different in babies whose mothers received theophylline compared with mildly asthmatic mothers not receiving theophylline and nonasthmatic mothers. Side effects in three babies with levels of theophylline greater than 10 microgram/mL were tachycardia and transient jitteriness. Newborns seem to tolerate theophylline levels corresponding to maternal levels without serious adversity; however, transient toxicity might occur with levels in the so-called therapeutic range.