Mine did with our first two and was right, he worked in the medical field so he knew some signs and symptoms of me possibly being pregnant, he was right both times. With our third and this one I knew before he did.
Medically & accurately, no he can’t. He can be saying it & be correct but just out of coincidence. My husband has guessed a few times I was pregnant when I wasn’t.
If they know your cycles pretty well yeah. My husband knew i was with our first when i just thought being sick throw off mine and saw the symptoms that i was having since i was more worried about other things.