Selective abortion of twin.

Selective abortion of twin

In the latest twist on the abortion dilemma, researchers are refining methods that allow selective termination of a defective fetus in fraternal-twin pregnancies. The controversial procedure allows parents to terminate an affected fetus, yet carry the healthy twin to term.

Usha Chitkara, Ricahrd L. Berkowitz and their colleagues at the Mount Sinai Medical Center in New York City studied 17 twin pregnancies in which one twin had a disorder, such as Down's syndrome, that would cause lifelong mental or physical handicap. The team carefully identified the affected fetuses and used a variety of methods to terminate it during the second trimester of pregnancy. They report in the May OBSTETRICS & GYNECOLOGY that a cardiac injection of potassium chloride was effective in stopping the affected fetus' heart. The dead fetus remains in the womb but shrinks in size and is expelled during delivery.

Chitkara performs the procedure only in fraternal-twin pregnancies, where the fetuses have separate circulatory systems. Identical twins often have connected circulatory systems, and a lethal injection given to one twin may harm the other, she says.

She and her colleagues dramatically improved their method during the course of the experiment. In the first six cases, four women lost the entire pregnancy. Then the researchers refined their technique and began using potassium chloride. The last 11 mothers, they report, delivered a healthy child.

The ethics of the procedure remain the toughest issue, Chitkara admits. In her experience, most of the couples with a severely defective fetus ultimately decided to undergo the experimental procedure rather than abort both fetuses or carry thm both to term. But "they really go through a lot of emotional turmoil before deciding to go ahead with it," Chitkara notes.