Kelsey Hatcher, a 32-year-old mom of three was born with a rare uterine anomaly called uterus didelphys, or two uteruses. However, she was not diagnosed with the condition until last spring, when she discovered she was pregnant – in each uterus.
Hatcher said her husband almost didn’t believe her.
“He said: ‘You’re lying,’ I said: ‘No, I’m not,” Hatcher told NBC News.
Uterus didelphys affects about 0.3% of women. The abnormality forms in the female embryo very early in development, around eight weeks gestation, according to fertility researchers.
Basically, they are only twins if they are born on the same day, because the concept of fraternal twins is basically being born from the same woman on the same day. Identical twins with the split egg after insemination are the only real “twins” biologically (except clones, generally illegal). There’s also roman twins, but those are pretty rare, because it involves a woman releasing two eggs but having intercourse with two different men in a roughly 48 hour time period, resulting in half brother fraternal twins.