Nobody knows what brought the tragedies to the families of men on the C shift.

The dozen Baltimore city firefighters eat together, sleep together and risk their lives together with the North Avenue Engine Company. In the past few years, they have shared another, disturbing experience.

From 1982 to 1984, the firefighters fathered eight babies, including three sets of twins. All of the babies were miscarried or born hopelessly premature; all of them died. During that time, a female paramedic on another shift gave birth to still another set of premature twins who did survive, despite serious complications.

"We tried to joke about it at first," said Kevin Higgins, 37, a pump operator. On Jan. 1, 1982, he and his wife, Mary Anne, became the first couple to lose their babies, twin girls born three months premature. Last November they produced the only full-term, healthy child born to the group since the series of miscarriages and premature births.

"We used to sit around the station," Higgins recalled, "and we'd say, 'My God, another set of twins. It must be something in the water.' "

Eventually, the firefighters did have their drinking water tested, in an independent effort to find out what was causing their problems. They examined fires they had fought for possible exposure to toxic materials. They checked out diesel exhaust. They considered sewer gas and a chemical unloading yard across from the station. But nothing could be pinpointed as a cause.

In January, Higgins began to focus his suspicions on the high-gloss paint the firefighters often used to touch up their equipment. The paint, a popular Du Pont Co. product called IMRON, contains a compound, ethoxyethanol, that has been found to cause certain reproductive problems in laboratory animals.

Although no specific link has been found and there is no scientific evidence to tie the paint to the local problem, the fire department last week removed the paint from all 57 of its firehouses. The firefighters union had urged the removal despite Du Pont's assertion that the product has never been linked to reproductive problems.

On Thursday, Ray Lloyd, the assistant commissioner of Maryland Occupational Safety and Health, said the agency will investigate whether the paint is to blame, also at the union's request.

However, Bryan Hardin, a toxicologist with the National Institute of Occupational Safety and Health (NIOSH), said it is unlikely that the paint caused the problems. Studies of ethoxyethanol showed that mice and rabbits developed sterility and infertility rather than a tendency toward premature births, he said.

Hardin said it is significant that personnel on other shifts and at other firehouses, who routinely used IMRON, have apparently not had a high degree of reproductive problems. Nor have problems in other cities come to light, although the paint is widely used across the country for industrial equipment.

Until conclusive evidence is found, the case remains a mystery both fascinating and sad. Maybe the firefighters came into contact with something harmful. Or maybe it is just a coincidence, one of those scarcely credible flukes.

"There's a chance it could be what is called 'a spontaneous cluster,' " Hardin speculated. "When you talk about one-in-a-million occurrences, well, maybe this is that one time."

The firefighters quickly dismiss that possibility.

"First of all, it is unusual that you would have that many pregnancies in such a short period of time in that small a group," said Jeff DeLisle, who represents the men as president of Local 734 of the International Association of Firefighters. "Then you have that many twins, that many lost, that same shift. Strange things do happen in life, but this is just too much."

Twins occur in one out of every 80 to 100 births. None of the affected families had a history of twins. Also, there had been no history of difficult births among the wives and girlfriends. Four had previously given birth to healthy children.

For the North Avenue firefighters on the C shift, the experience has had a series of effects.

"There's been an awful lot of heartache in that one firehouse," said one firefighter's wife, who did not want to be identified.

Only Higgins, who is a union official, has discussed the situation publicly. Others, not wanting to antagonize their superiors, refer questions to the fire department's public information office.

The infant deaths caused sadness, guilt and depression. Several of the wives sought counseling after losing their babies, Higgins said.

And the situation has drawn an already close-knit group even tighter, although it went largely undiscussed.

On the C shift, firefighters work from 7 a.m. until 5 p.m. for four days and are off for two days. Then they work 14-hour shifts on four successive nights, from 5 p.m. until 7 a.m.

The result is a rare closeness among coworkers and their families. When the firefighters are not out on calls, their wives or girlfriends often come over to the firehouse and eat dinner with them in a big open room on the first floor. The men catnap in bunks upstairs. They touch up and repair their equipment. They answer about 1,400 calls a year.

"It was not so much what anybody said about their problems," said Higgins. "It was what you'd see -- like, someone not coming to work on time or not doing his job as well or acting like he wasn't all there.

"There was a lot of drinking. It's an escape. After we lost our babies, I went out and got plastered. Believe me, it doesn't help."

For Higgins, that unhappy period is past. On a recent afternoon, he sat in his Baltimore row house, cheerfully baby-sitting for Kevin Jr., 5 months old. His son is the first child born to the group since the last premature infant died in March 1984.

Higgins talked about the paint and his suspicions while giving a bottle to Kevin Jr., who is teething and was feeling a little irritable.

"I stopped working with the stuff about a year and a half ago," he said. "One day a sprayer blew up in my hand and all I could see for a minute or two was orange. I said, 'That's it.'

"The studies say that the effects of exposure to ethoxyethanol are temporary," he said, kissing the baby's forehead. "Maybe that explains him."

When Mary Anne Higgins became pregnant again, the couple entered an anxious period that often seemed interminable.

"What if it happened again?" said Higgins. "That was always in the back of our minds. We were scared. And we were scared the whole nine months. But he's worth it."