Too much of a good thing

Patients undergoing IVF treatment should avoid unprotected sex, say Stanford
doctors who implanted two embryos into a woman only to find later that she was
pregnant with quads. “We were surprised, amazed and very curious,” says Mary
Hinckley of the Department of Gynecology and Obstetrics. Genetic testing after
the babies were born has revealed that while the implanted embryos developed
into fraternal twins, the woman also conceived identical twins after having sex
around the time of implantation.