Board Thread:Theories and Speculation/@comment-3365837-20160826052003/@comment-734582-20160827182252

Heliosraven wrote: You should read the full post I did. I already addressed that: the other jinchuriki were extremely unlike to ever get pregnant, as they were considered nothing but tools. The females we know of have no known partners.

And again: pregnancy is very telegraphed, the jinchuriki were kept under surveillance and preparations could be made like Minato did. It's a minor problem. And considering that many nations had a lot of problems controlling their biju, they may as well have tried to see if women had better odds. It remains to be seen if jinchuriki children have some of the biju's power rub off, but i guess they could've been secondary goals in this.