BOSTON — Cocaine use during pregnancy, which experts say has risen in recent years, appears to increase the risk of miscarriages and cause unresponsive, erratic behavior in newborn infants, a new study published in today's New England Journal of Medicine concludes.
In addition, the researchers said that their work contains a troubling hint that cocaine use by pregnant women might increase the odds of physical birth defects in their babies.
The study, conducted at Northwestern Memorial Hospital in Chicago, was based on a survey of 23 heavy cocaine users and their children. The study's director, Dr. Ira J. Chasnoff, said the findings were released despite the relatively small numbers because they were "of such consequence and the cocaine problem is so bad."
Chasnoff said that the findings could help explain why children of drug abusers are more likely to be victims of child abuse.
When tested at the age of 3 days, the babies of the cocaine users often failed to respond to talking, cooing or other attention from their parents.
"If the infant is passive, the mother becomes resentful and passive, and the more passive the mother is, the more passive the infant becomes," he said. "It's very easy to understand how that can lead to child abuse."
Chasnoff said the babies were also emotionally fitful. For instance, they would scream uncontrollably when startled and then abruptly fall asleep.
"It's a yo-yo effect," he said. "Their emotions are right on the edge. These infants don't have the ability to respond with the proper emotions."
The study was conducted on four groups of expectant women: 12 who used cocaine, 11 who used cocaine and heroin, 15 who took methadone and 15 who did not use any of those drugs.
Medical histories showed that the cocaine-using women were far more likely than usual to have had miscarriages, or spontaneous abortions. Thirty-eight percent of the cocaine users had had spontaneous abortions, as had 46% of those who used both cocaine and heroin. None of the drug-free women had had miscarriages.
During the pregnancies that were studied, several of the women reported feeling contractions and increased movement of their fetuses within minutes after using cocaine.
Four of them experienced detachment of their placentas from their uterine walls and the start of labor immediately after injecting themselves with cocaine.
"We can theorize that, when a woman takes a heavy dose of cocaine, it could interrupt the blood supply to the placenta and fetus," Chasnoff said. "If there's a severe enough interruption, she's going to abort."