@Tomfafa if they live in NY as I see you do, legal abortion should be fairly available if that is what they decide on. Some more rural states have major psychological and geographic hoops that have been set up to make medically safe abortion feel less accessible.
Ideally, this young couple needs some counseling about the choice they’re facing – it has to be the girl’s decision about whether to continue the pregnancy or end it, and if she continues, whether to parent or adopt. You nephew should be telling her how he feels about the options, but in the end, he needs to support her in her choice.
Sometimes families can help teens sort through this without pressuring to create the outcome they the older adults want and sometimes not. Can you help your nephew and his girl get the counseling they need ASAP? They may want to have their own thoughts sorted out and decisions made before they face their parents. It’s possible the girl doesn’t feel she can involve her parents at all.