Most of the health problems reported after the Sept. 11, 2001 attacks have involved respiratory difficulties and mental distress, according to a U.S. government report published on Wednesday.

Firefighters and other emergency workers showed long-term respiratory problems, including a syndrome called “WTC cough.”

A separate study published on Wednesday also showed subtle but significant effects on pregnant women and their babies.

The hijacked plane attacks that destroyed the World Trade Center created infernos that enveloped much of New York in a pall of smoke and dust loaded with toxic chemicals. Nearly 3,000 people were killed in the attacks and a similar one on the Pentagon in Washington.

“The primary health effects include various injuries, respiratory conditions, and mental health effects,” the Government Accountability Office, the investigative arm of Congress, said in a report summarizing the health problems.

“In the immediate aftermath of the attack, the primary injuries were inhalation and musculoskeletal injuries,” said the report, published on the Web at [url=http://www.gao.gov]http://www.gao.gov[/url]

“A range of respiratory conditions have also been reported, including wheezing, shortness of breath, sinusitis, asthma, and a new syndrome called WTC cough, which consists of persistent cough accompanied by severe respiratory symptoms,” it said.

“Almost all the firefighters who responded to the attack experienced respiratory effects, and hundreds had to end their firefighting careers due to WTC-related respiratory illness.”

The GAO said six separate registries had been set up to monitor reports of health problems following the attacks. “Some long-term health effects, such as lung cancer, may not appear until several decades after a person has been exposed to a harmful agent,” it said.

“The most commonly reported mental health effects include symptoms associated with depression, stress, anxiety, and post-traumatic stress disorder.”

In a separate study in the journal Environmental Health Perspectives, researchers found that pregnant women who were close to the twin towers at the time of the attack were more likely to give birth to lighter babies.

The Columbia Center for Children’s Environmental Health surveyed 300 nonsmoking women who delivered babies at three hospitals in lower Manhattan. Babies born to the women living within two-miles of the site weighed on average 149 grams or 5.2 ounces less at birth compared to infants born to the other pregnant women.

“This study indicates that fetal growth and length of gestation were significantly reduced as a result of exposure to pollutants or stress, or both, from the destruction of the World Trade Center, and shortened gestation means smaller, less mature babies,” said Dr. Sally Ann Lederman, who led the study.