i doubt it.
you two were not minors, his mom had no part in this obviously, he is most likely saying this out of anger.
what are you going to do?

No, he cannot press charges. For what? Underage sex?

He sounds like he's just angry. But, the thing is, why does your dad think the mother of your boyfriend should be reported, yet not himself? Why does he feel the mother is responsible in any way for what you two did?

he cant press charges on you or anyone involved. In most places 16 is the legal age of consent and there is nothing that he can do about the fact you became pregnant. He is probably just upset and it will blow over, hopefully. If he isnt supportive though and you are going to keep this baby you need to come up with a plan of action and get somewhere where you can have help and support.