This research is very interesting. I even don't think about it. to have a baby 22nd May you need to conceive in the end of august, I don't understand why it is the least common birthday) Maybe someone can tell me

22nd May is considered to be the least common birthday according to some survey in America. On the other hand, 5th October is the most common birthday. To have a baby on 5th October, you need to conceive in the new year's eve.