The Buddhist country of Thailand will allow abortion in cases when fetuses have proven birth defects that are linked to the Zika virus, according to a Reuters report. While the practice is still technically illegal, officials are allowing it on a temporary basis in this special circumstance.

Thailand confirmed its first known case of microcephaly linked to the Zika virus, which is spread by mosquitoes and has been running rampant in South and Central America. Two cases of the birth defect, which results in small heads and brain damage, were the first reported in Southeast Asia. Zika is already causing widespread birth defects in the Americas.

Health officials will be drafting guidelines for expectant mothers, and say that abortions can be carried out at up to 24 weeks for serious birth defects caused by Zika.

“The difficulty with Zika is to determine microcephaly. It is usually found later in pregnancy,” Pisek Lumpikanon, president of the Royal Thai College of Obstetricians and Gynaecologists, told Reuters. “Legal medical abortions can be done up to 24 weeks. The reason is that at 24 weeks and after the baby already has a good chance of survival.”

Abortion is illegal in Thailand, except in cases of rape or to save the woman’s life. In those cases, it must be carried out in upt o 12 weeks of pregnancy — after that, it is decided on a case by case basis.

While there is no test that can prove a child has microcephaly, ultrasound scans allow it to show up in the third trimester.