User blog comment:B214/High School DxD EX/@comment-24053170-20160113224250/@comment-24053170-20160114023704

I know that, but you also have to remember that Ophis is considered a member of Isseis harem too. Since Ishibumi himself stated that fact. Besides, Ophis can take any form or gender it wants, and she stays in the form of a female loli when around Issei.

Ophis is like Loki from the actual norse myths in that he became a female horse and gave birth to Sleipnir. So I wouldn't be surprised if Ophis could give birth if she remained in female form too.

Besides, given the extreme/insane nature of this series anything is possible. ^^