Most Americans say they support an Obamacare rule that calls for employers to offer birth control coverage in their health plans, a new study says.

The national survey, conducted by researchers in the University of Michigan Health System, showed that 69 percent of adults support universal birth control coverage. The findings were reported this week in the Journal of the American Medical Association.

Women, blacks and Hispanics were more likely to support coverage of birth control mandates than were men, older individuals and adults without children in the home, the study showed.

"In other words, support is higher among individuals who may be more likely to directly benefit from affordable birth control," said lead author Dr. Michelle Moniz, an obstetrician, gynecologist and researcher at the University of Michigan Medical School.

Less than 10 percent of adults don't support contraceptive coverage but do support the other services covered under Obamacare, the study says. This group included a significantly higher percentage of men, adults over the age of 60 and Americans without children in the household.

The Affordable Care Act provides for a range of free preventive care, including 20 forms of contraception. The Obama administration has strongly defended the provision, saying it puts women in control of their health care.

The Supreme Court is expected to rule in June on whether businesses can opt out of the health care law's contraception mandates on religious grounds.

The case centers on two Christian-owned companies opposed to emergency contraceptives like the morning-after pill and certain intrauterine devices, arguing that life begins at conception and that destroying an already fertilized egg in the uterus is tantamount to abortion.

The justices appeared divided on the issue during oral arguments for the case last month.