An Australian woman has given birth to twin girls conceived 10 days apart. Kate was diagnosed with polycystic ovarian syndrome (PCOS), a hormonal condition that left her unable to ovulate, in 2006.
She had been having hormone injections to help boost her fertility.
She and husband Peter soon found out they were pregnant with two babies, conceived at different times, even though the couple say they only had unprotected sex once.
“What makes this case even more rare, is that my husband and I only had intercourse one time — his sperm stayed alive for 10 days to fertilise the second egg released,” Mrs Hill said.
Nine months later, she gave birth to two baby girls, Charlotte and Olivia. “We actually didn’t realise how special that was until they were born,” she added.
This rare occurrence is often referred to as superfetation, said Royal Australian and New Zealand College of Obstetricians and Gynaecologists President, Professor Michael Permezel. It’s believed there are only 10 or 11 cases of superfetation in the world.
“[Charlotte and Olivia] are classified as twins,” Prof Permezel told news.com.au.
“Normally with twins, both eggs are released at the same time and conceived at the same time.
But in this case, one egg appears to have been released 10 days later and the sperm survived in the female genital tract before fertilising the other egg.
“We do know that sperm can survive in the female genital tract for up to a week, but usually not for 10 days.”