Karol Kaltenbach is devoted to a clientele that most of society would rather not even think about: mothers hooked on opiates such as heroin.

As director of maternal addiction treatment and research in the pediatrics department at Thomas Jefferson University, Kaltenbach knows too well that such women are stigmatized, underserved - and tough to help because their needs are vast and complex.

That's why she is excited about the results of a major international study she helped lead that compared treatments for pregnant addicts.

A drug called buprenorphine worked as well as the current standard, methadone, at keeping the women off more harmful opiates. Better, buprenorphine had dramatic advantages when the women gave birth. It caused far less hyper-irritability, feeding difficulties, digestive upsets, and other miseries in their newborns as the infants went through opiate withdrawal.

Both methadone and buprenorphine are synthetic narcotics with side effects such as euphoria. But buprenorphine, approved for addiction therapy in 2002, works in a way that reduces opiate dangers such as sedation, slowed breathing, and overdose.

Two older buprenorphine studies - both tiny - had inconsistent results in babies.

"These are very difficult studies to conduct," Kaltenbach said, because of eligibility restrictions, high dropout rates, and protocols. Women in the new study, for example, had to show up every day to get their medication. If they missed five days in a row, they were disqualified.

Ultimately, 131 women at eight sites, including Jefferson, finished the study. All the babies had withdrawal symptoms, but the ones exposed to buprenorphine needed intensive therapy for an average of four days, and went home after 10 days, while the methodone-exposed babies needed 10 days of care and 18 days in the hospital.

"It's extremely gratifying," Kaltenbach said. "We do think it's going to transform clinical practice."

And one hopes, cut costs. The study, published last week in the New England Journal of Medicine, noted that the United States spent up to $112 million last year to treat babies born to opioid addicts.