A surprising study showing that AZT prevents transmission of the AIDS virus from pregnant women to their babies has already affected one HIV-infected Boston mother-to-be.

[Ken McIntosh] said he wanted to make sure the mother got the drug during delivery. It turned out she wasn't ready to deliver, but her supply of pills - the doctors don't know who gets the AZT and who gets the sugar pill - was fast switched with pills known to be AZT.