[He gave Steve a filthy and unimpressed look at the automatic question about the paternity of the little butterfly fluttering inside of him. There was no question that he had mated only with Steve, and it had been often enough lately that there could be no other choice in his mind. Nothing in his memory indicated that HYDRA agents dared to come that close to him, and if they did, they ended up with their throats ripped out.

He wasn't showing too much, but he was still putting on weight for density. He softened at the large warm hand that passed over his belly, humming a soft sound and subsiding from the urge to bite his mate.]

I doubt it would be possible without previous intervention. I know there was a time when males of my species were entirely wiped out from disease. Females bred females in those bad times at sea.