@hi. like in most omega verses when the omega is pregnant before they actually find out is usually when they see like a animal or something in their dreams, also you can kinda tell since his body doesn't like other peoples pheromones and only likes the alphas he's usually with (I forgot their names to bare with me 😭😭).
yall got any BL recommendations please share 
or any manwha recommendations is greatly appreciated also 
or any manwha recommendations is greatly appreciated also