Methamphetamine Stunts Fetal Growth

TORRANCE, Calif., Sept. 7 -- Babies born to mothers who used methamphetamine during pregnancy are 3.5 times more likely to be small for their gestational age than children of non-users, according to researchers here.

The findings are similar to those seen in infants born to cocaine-using mothers, and they suggest direct growth-restrictive effects of in utero methamphetamine exposure, reported Lynne M. Smith, M.D., of the Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, here, and colleagues, in the September issue of Pediatrics.

"Both of these drugs are central nervous stimulants, and it appears that both drugs have similar effects on the developing fetus," said co-author Barry M. Lester, Ph.D., of the Brown Center for Children at Risk at Brown University in Providence, R.I.

"But I hope that the 'crack baby' hysteria does not get repeated," Dr. Lester continued. "While these children may have some serious health and developmental challenges, there is no automatic need to label them as damaged and remove them from their biological mothers. There are alternatives for the mother and the baby that can keep families together, such as the specialized drug court we established here in Providence that is based on treatment, rather than punishment."

The authors studied the effects on fetal growth of methamphetamine use during pregnancy as part of the multicenter, longitudinal IDEAL (Infant Development, Environment and Lifestyle) study.

The investigators enrolled 1,618 mothers at four clinical centers in cities where methamphetamine use was known to be a problem: Los Angeles, Des Moines, Tulsa, and Honolulu.

The investigators identified 84 newborns who were exposed to methamphetamine in utero, and 1,534 who were not exposed. Drug exposure was ruled in or out by a combination of self-reports by the mothers and by gas chromatography-mass spectrometry confirmation of amphetamine and metabolites in the infants' meconium.

In both groups some mothers had used alcohol, tobacco, or marijuana during pregnancy, but any who had used opiates, LSD, PCP (phencyclidine), or cocaine were excluded.

The investigators looked at neonatal birth weight and gestational ages in weeks, and conducted one-way analyses of variance, as well as linear regression analyses on birth weight by exposure. They also looked at the relationship between methamphetamine exposure and the rate of small-for-gestational age births.

They found that the children who were exposed in utero to methamphetamine were 3.5 times more likely than unexposed children to be small for their gestational age. A similar but somewhat less powerful effect was seen with tobacco use, with women who smoked during pregnancy being twice as likely as non-smokers to give birth to infants who were small for their gestational age.

The mothers who used methamphetamine were more likely to have a lower socioeconomic status, live in a household earning less than ,000 per year, be on Medicaid, live without a partner, and they were more likely not to have finished high school.

The drug users also tended to be younger, to seek prenatal care later in pregnancy, have fewer visits for prenatal care, and, somewhat surprisingly, to gain more weight during pregnancy relative to non-users.

To determine the reason for this unexpected finding, the authors compared weight gain between mothers who used methamphetamine only through the first or second trimester with weight gain among women who used the drug throughout pregnancy.

"Those who quit using methamphetamine earlier in gestation gained 10 lbs. more than those who continued to use throughout pregnancy (P=0.019), suggesting that the anorexic effects of methamphetamine are limited to continuous use, and there may be a rebound in weight gain if the mother quits," they wrote.

Meth-exposed infants were also more likely to be born pre-term (less than 37 weeks gestation). In all, 12.5% of the drug-exposed infants were born pre-term, compared with 6.5% of those who were not exposed (P=0.036).

Methamphetamine may affect fetal growth by altering maternal and fetal hemodynamics and by suppressing the mother's appetite, thereby depriving the fetus of adequate nutrition, the authors suggested.

The investigators plan to follow the children in the study until they are at least three years old.

The IDEAL study is funded by the National Institute on Drug Abuse and the National Center for Research Resources.