New York ? New Jersey this week launched one of the most ambitious efforts in the country to control mother-to-child transmission of HIV, making screening tests mandatory for all pregnant women in the state beginning next year.

A bill signed into law Wednesday by the Senate president, Richard J. Codey, in his capacity as acting governor, requires two tests for pregnant women, at the beginning of the pregnancy and again in the third trimester, unless the mother objects. If the mother objects, the objection will be noted and the newborn will then be tested for HIV, with the only exception being on religious grounds. Newborns will also be tested if the woman tests positive.

Just four other states have mandated testing for pregnant women, and three more require screening of newborns. But New Jersey’s law appears to go further by requiring both.

The mandatory screening has raised privacy concerns. The American Civil Liberties Union of New Jersey and the state’s chapter of the National Organization for Women both questioned whether the mandated tests violate a woman’s right to privacy and the right to make her own medical decisions.

Riki E. Jacobs, executive director of the Hyacinth AIDS Foundation, a New Jersey nonprofit helping people living with AIDS, said the law is unnecessary and comes when the state should be focused on expanding care for pregnant women. “I am adamantly opposed to this bill. New Jersey already reduced the perinatal rate of transmission with mandatory counseling of pregnant women,” she said. “The issue is getting those women who are not in prenatal care in for services and testing.

“I definitely think it is an invasion of privacy,” Jacobs said. She said women choose to test their babies in 98 percent of cases, so the new law’s mandatory provisions for testing children are not needed: “The fact that we assume women won’t choose to test is ludicrous and wrong.”

But in the end, lawmakers decided that the risk of exposing children to the infection outweighed those concerns.

While men represent the majority of new HIV and AIDS cases in the United States, women now account for an increasing share, from just 8 percent of new diagnoses in 1985 to 27 percent in 2005, according to the Kaiser Family Foundation. Of the estimated 1.2 million people living with HIV/AIDS in the United States in 2005, about 300,000 were women, and the vast majority were between 25 and 44 years old.

The U.S. Centers for Disease Control and Prevention, among other groups, has been recommending that HIV screening become a routine part of prenatal tests. The CDC recommended HIV tests become a routine part of the battery of prenatal tests, and that there be no separate written consent required.

Mother-to-child transmission of the disease – during pregnancies and through breast-feeding – peaked in the United States in 1992, according to the Kaiser Family Foundation, which reported that the number of cases since then has dropped “dramatically” because of early detection and the increased use of antiretroviral therapy, which lowers the risk of transmission to less than 2 percent.

The majority of those new cases that still occur are mostly among black Americans, reflecting the changed demographic of the epidemic since it was first identified.

According to the CDC, 100 to 200 children a year are infected by their mothers. As of 2005, the last year for which figures are available, there were 6,051 people in the United States living with HIV/AIDS who had been infected perinatally – during pregnancy or breast-feeding.