The Japan Society of Obstetrics and Gynecology said Monday that it will officially allow those in common-law marriages to undergo in vitro fertilization, relaxing a longtime voluntary curb.

JSOG, which has about 16,000 members nationwide, will ease the criteria for in vitro fertilization in line with a September ruling by the Supreme Court that said a clause in the Civil Code that denies full inheritance rights to children born out of wedlock was unconstitutional.

The move may also prompt the health ministry to consider providing subsidies for the treatment to common-law couples, sources said. Currently, the treatment is not covered by insurance, but subsidies are provided to legally married couples in certain conditions linked to age and income.