(AP)—An Austrian university says that the number of newborns deliberately killed within 24 hours of their birth has been cut by more than half in the country because of a law allowing mothers to remain anonymous during and after delivery.

's medical university says the rate dropped dramatically after the law was passed in 2001. In a study it made public Wednesday, the university says that around three in 100,000 were killed between the years 2002 and 2009, compared to about 7 per 100,000 between 1991 and 2001.

The study says the rate did not fall between 2002 and 2009 in Sweden and , which do not allow for anonymous delivery.

The study estimates that between 30 and 40 women in Austria make use of the law annually.