Six months from now, an HIV test will become part of the routine prenatal test for pregnant women in New Jersey.

Under the law, women will be tested early in their pregnancies and again in their third trimesters unless they refuse. If a woman refuses, it will be noted, and an H.I.V. test will be performed on the newborn unless the mother has religious objections.

This move is meant to prevent infection in babies of HIV-infected mothers. If the mother turns out to be HIV-positive, then early medical intervention can be done such as prescribing antiretroviral drugs and Caesarian section delivery, to reduce the risks of the child becoming infected.