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.

The JSOG’s voluntary rule states that in vitro fertilization can be performed on “married husbands and wives who strongly desire to bear children.”

Hideo Aono, an JSOG official, said the term “married” would be dropped from the rule, which was written in 1983 when the first in vitro baby was born in Japan.

On top of the unequal inheritance rights that children born out of wedlock could face, being husbands and wives basically meant they were legally married back then, so the JSOG had apparently not qualified common-law married couples for in vitro fertilization, Aono said.

The relaxed rule will also help doctors, because privacy issues had made it difficult to confirm whether couples are legally married, and thus it was left up to physicians to determine the status of those seeking treatment in lieu of screening them with questions and formal documents to completely make sure. The submission of a family registry has not been mandatory when seeking in vitro fertilization.

The relaxed criteria are a way to apply the Supreme Court’s decision to current realities, Aono said.

A married couple with a combined income below ¥7.3 million can qualify for subsidies for in vitro fertility treatment.

Information from Kyodo added.