So people have been confused of how could Saiki and the other guys are pregnant and know one is freaking out.

Let's begin

Only 48% of the male population can get pregnant and that's how it has been for.the past century. Male pregnancy varies from person to person. Some have menstrual cycles while other don't. Some may have birth canals and some don't . All in all they can get pregnant .

A male pregnancy lasts for 9 months like a normal one but for Saiki's case his one last for about 4 months due to his abilities.

Children know that they are carriers (that's what they are called) from birth . Some parents if they have the money can  change this however this is not always successful.

I hope this clears up everything .