Mother's Smoking Linked to Muscle Problems in Infants
NEW YORK (Reuters Health) - Cocaine use during pregnancy can cause serious complications in infants. And researchers note that many women who use cocaine also smoke cigarettes. Now, US researchers report that cigarette smoking and not cocaine use during p
"The majority of babies that are born to moms that use cocaine are normal, but this specific population does show a higher prevalence of hypertonia,'' according to lead researcher Dr. Delia A. Dempsey of San Francisco General Hospital in California.
Approximately 80% to 90% of people who abuse drugs also smoke, and studies that have investigated adverse effects of drugs on infants whose mothers abuse drugs may overlook this fact, the researchers note in the July issue of Pediatrics. The goal of the study was to determine what effects cocaine exposure had on infants, while also taking into account the babies' exposure to cigarette smoke.
The study, which looked at 40 cocaine-exposed infants and 56 infants not exposed to cocaine during pregnancy, analyzed for metabolites breakdown products of cocaine and cigarette smoke. All the infants were roughly 6 weeks of age at the time of the examination.
Cotinine, a major nicotine metabolite with a long half life, is a widely used quantitative biomarker of cigarette smoking and gives more accurate prevalence rates than smoking histories or from counting the number of cigarettes smoked per day.
The researchers found that cotinine levels in the mother's urine could be used to predict abnormal neurological findings in the baby. Mothers with high cotinine levels had a three times greater risk of having a baby with hypertonia.
"This biomarker actually tells you the degree of the baby's exposure to these substances...it's more than just a yes or no answer,'' Dempsey told Reuters Health.
In contrast, cocaine exposure was not linked to hypertonia in the infants.
The findings suggest that "some outcomes that have been attributed to in utero cocaine exposure may actually be attributed to maternal cigarette smoking,'' Dempsey and colleagues conclude.
However, the investigators also note that it is not clear what effect hypertonia in infancy has on the child's development, "but it may be a marker for later childhood cognitive (learning and memory) or behavioral problems.''
"How this will affect these babies later in life is not known,'' added Dempsey.