Poland’s lawmakers on Thursday approved a government bill that provides coherent regulations for in vitro fertilization and guarantees the procedure also to unwed couples. The vote was a big step toward giving IVF a solid and comprehensive legal framework. It still needs approval from the Senate and the president, who are expected to back it, as the government is taking steps to increase the number of births in the aging nation.

Prime Minister Ewa Kopacz said it was a “success of Poland’s freedom” and a “chance for some happiness” for the couples involved.

The lower house, or Sejm, voted 261 for the bill, 176 against, with six abstentions. Most of the ruling coalition voted for the bill, while the conservative, Catholic opposition Law and Justice party voted against, saying that IVF breaks the constitutional right to life and treats embryos as an object rather than a human being. The opposition warned it may take the bill to a special court that rules on the constitutionality of new laws.

Poland’s influential Catholic Church opposes the bill.

Under the bill, married and unwed couples will be eligible for IVF if other treatments give no results in 12 months. A couple can have up to six eggs fertilized. Those unused can be offered for use by other women after 20 years, but cannot be destroyed. The bill bans techniques that would influence the embryo’s gender or other features.

Poland already allows IVF in licensed clinics, but lacks coherent legal and logistical regulations. In a recent blunder, a woman was implanted with the wrong egg.