Superfetation: How an Australian Woman Got Pregnant Twice in 10 Days

An Australian woman receiving hormone treatment for polycystic ovary syndrome, a condition that prevents women from ovulating, got pregnant twice in 10 days.

According to the report from BBC New, Kate Hill had unprotected sex with her husband Pete Hill, making her pregnant. Then, ten days later, without any unprotected sexual intercourse with her husband, Kate became pregnant with another child.

"We were shocked, scared and excited all at the same time," Kate told Us Weekly. "Throughout our pregnancy we were constantly worried about their growth and how much smaller baby No. 2 would be."

Kate's pregnancy is a very rare medical phenomenon called superfetation. This condition is so rare that there are only 10 reported cases in the world. Superfetation occurs when a woman continue to ovulate even after conceiving. The second egg could be fertilized by any lingering sperm in the fallopian tube and uterus of the women. The second conception occurs when the second fertilized egg implant itself in the lining of the womb.

As oppose to the usual process of fraternal twins where two eggs were released by the ovary and fertilized at the same. In a rarer identical twin, a single fertilized egg splits into two embryos, creating two babies with exact same genetic makeup.

Despite having different due dates that were ten days apart, Kate's twin were born on November 29. Kate and Pete named their twins as Charlotte who weighed 4.23 pounds and Olivia at 5.46 pounds. Kate claimed that the twins are a bit different with each other. Olivia is more like the loud and adventurous sister while Charlotte is the cautious one.

According to the Centers for Disease Control and Protection, there are 135,336 twin births in the United States, with 33.9 per 1,000 live births were twins. Furthermore, there are 47 cases of quintuplets and other higher order births.