About 2,800 underage indigent women have been sterilized in the last two years despite government regulations imposed in 1973 to stop such procedures, new federal figures show.

The sterilizations performed on Medicaid patients under 21 years old since 1977, as reported last week old since 1977, as reported last week by the Health Car Financing Administration, represent 2 percent of all the government-funded sterilizations performed in 1977 and 1978.

The figures showed that Maryland has one of the highest proportions of sterilizations of patients under 21. Ten percent of Medicaid sterilizations in the state were performed on underage women, while the national average is 2 percent. Only Wisconsin and Oregon had such high percentages.

Maryland continued to fund sterilization of patients from 18 to 21 with Medicaid money until April of this year, according to John J. Kent Jr., assistant secretary of the Maryland Department of Health and Mental Hygiene. About 1,400 Medicaid-funded funded sterilizations have been performed in Maryland annually in the past three years, of which 125 to 150 yearly have been on patients under 21, he said.

Maryland has been involved in a battle with the federal government for several years regarding the age at which a patient may give informed consent to sterilization. Since 1973, when a court case about teen-agers sterilized in Alabama received widespread publicity, federal guidelines have forbidden Medicaid funding for sterilization of any patient under 21. Stricter guidelines were issued this year.

However, Maryland, like some other states, has continued to claim federal money for such sterilizations. Doctors and state health officials felt that since a Maryland resident is legally considered an adult at 18, he or she should have as much right to consent to medical sterilization, including vasectomies for males, as to sign any other contract.

Federal officals disagreed, and in 1976 they disallowed payment of $70.000 in Medicaid funds to the state for sterilizations performed during the preceding year that failed to conform to guidelines. There have been no further disallowances because the state is still appealing the guidelines, although Kent said Maryland brought its regulations into line with the federal age limit of 21 last April.

Nationwide the government has disallowed almost $12 million since May 1975 for sterilizations failing to conform to guidelines.

The statistics indicated that the vast majority of sterilizations performed were tubal ligation, in which a woman's fallopian tubes are cut or tied to prevent eggs from reaching the uterus. Such an operation is usually irreversible.

Federal officials now plan to track down the sterilizations of minors state by state, and disallow funds for any in which payments have not already been refused, according to a statement by Leonard D. Schaeffer, of the Health Care Financing Administration.

If states fail to comply with federal guidelines, they can only be penalized by this kind of retroactive withholding of Medicaid money, officials said.