TORONTO -- Methamphetamine can be detected in the hair of newborns, the first direct evidence that crystal meth can cross the placenta and affect the growing fetus, researchers here reported.
TORONTO, Nov. 2 -- Methamphetamine can be detected in the hair of newborns whose mothers used the drug during pregnancy, researchers here have found.
It represents the first direct evidence in humans that crystal meth, which is a growing drug-abuse problem in North America, can cross the placenta and affect the growing fetus, according to Facundo Garcia-Bournissen, M.D., of the Motherisk program at the Hospital for Sick Children.
Researchers at the program have been testing hair samples from parents and adults across Canada for several years, usually when there is clinical suspicion of drug abuse on the part of parents, Dr. Garcia-Bournissen and colleagues reported in the online issue of Archives of Disease in Childhood.
From June 1997 through December 2005, the database accumulated results of 34,278 tests for drugs in hair, representing 8,270 people. Nearly 60% (or 4,926) of these people were positive for at least one drug of abuse, the researchers said.
In a retrospective analysis, Dr. Garcia-Bournissen and colleagues examined the incidence of methamphetamine in hair samples:
The median methamphetamine values in the mother-baby pairs were 1.75 ng/mg for the mothers and 1.63 ng/mg for the newborns. Dr. Garcia-Bournissen and colleagues said.
The median concentrations were not significantly different, "suggesting that the transplacental transfer of methamphetamine is extensive," the researchers said. On an individual level, maternal and neonatal drug levels correlated significantly (at P=0.003, using Spearman's rho test, with r=0.8).
Interestingly, among the 171 subjects who were positive for methamphetamine and whose hair was tested for other drugs, 83.5% were positive for at least one other drug, usually cocaine, Dr. Garcia-Bournissen and colleagues found.
In contrast, among the 1,053 subjects negative for methamphetamine but positive for some other drug, only 38% were positive for more than one drug, they said.
"Positive exposure to methamphetamine strongly suggests that the person is a polydrug user, which may have important implications for fetal safety," the researchers said.
The effects of the drug on the exposed child remain unclear, Dr. Garcia-Bournissen and colleagues noted, although there is some evidence that "children exposed in utero to methamphetamine are at risk of developmental problems, because of either the effect of direct exposure to the drug during pregnancy or growing in the environment associated with parental methamphetamine misuse, or probably both."
Because the study was retrospective and anonymous, clinical information on the exposed infants is not available, the researchers said.