This year, more than half of American mothers with children 1 year old or younger will go to work. Tough economic and family situations are forcing many women to the labor force shortly after childbirth.

What responsibility do employers have to these women who give birth while on their payrolls?An answer may be found in the Family and Medical Leave Act, which as been on the calendar in the U.S. House since early spring.

The compromise bill, sponsored by Rep. William Clay, D-Mo., provides an employee - male or female - up to 10 weeks of unpaid leave within the first year after the birth or adoption of a child. It also mandates a guarantee of the same or equivalent position upon return. In addition, either the employee of employer may substitute existing paid leave for any part of the unpaid leave.

Not everyone is covered, however. Workers would have to be employed for at least one year and work 20 hours a week to be eligible for unpaid leave, and only employers with 50 or more workers for the first three years after enactment, and 35 workers thereafter, would be included in the law.

Such an exemption would exclude nearly 95 percent of all employers from the bill, although General Accounting Office estimates 1.7 million workers a year would still be eligible under the law.

Several state legislatures have sensed a growing need for regulation. A January 1987 Supreme Court decision upheld a California law requiring most of the state's employers to give women workers up to four months of unpaid, job-protected leave. The rule of thumb for normal pregnancies is six weeks off after birth and four weeks before, but each case is reviewed. If the leave goes beyond that, the need must be verified by a doctor. The law also allows women to use their accrued sick pay and vacation time for maternity leave.

Oregon has one of the newest - and perhaps most innovative - maternity laws in the nation. According to Don Jepson of the Bureau of Labor and Industry, the 1987 Parental Leave Law allows up to 12 weeks leave, with job guarantee, following the birth or adoption of a child under 6 years old. Fathers can even share the leave time with their wives, as long as their total time off doesn't exceed 12 weeks.

The bill was hotly debated, and the National Federation of Independent Businesses and other big business associations fought against its passage.

John Redd, R-Bountiful, who sponsored the only pregnancy-related bill in the 1988 Utah Legislature, said he knows of no recent efforts to establish laws covering maternity leave.

"There's quite a gap that needs to be covered in the state," Redd said.