A woman undergoing in vitro fertilization (IVF) treatment became pregnant at a Tokyo hospital this spring after concealing from doctors that her husband, who was believed infertile, was actually dead, according to hospital officials and sources close to the matter.

The incident at Hara Medical Clinic in Tokyo's Shibuya Ward has raised concerns over the ramifications for the child's biological father as infertility treatments in Japan are limited to married couples, and when donor sperm is used the husband usually assumes legal parenthood.

Japanese law does not cover cases in which the husband dies during IVF treatments. It is possible that, if identified, the sperm donor may be asked to legally accept recognition as the child's father.