My step son just found out that his girlfriend is pregnant and he is assumed to be the father by all parties involved. He would like to not only do the right thing in caring for the child after birth he wants to be able to attend doctor appts and receive any information regarding the child during the pregnancy and to make sure that the mother doesn't seek an abortion or adoption. The girlfriends family although excited to have a grand baby on the way is now preventing the assumed father from contacting or seeing his girlfriend for the sake of the child. They both live in the state of Missouri. Any help would be great.

How old are they both?

First off... he has no rights to stop her from seeking an abortion, he does have a say on an adoption however.(within limits). Second.. until its legally established he is the father... through a DNA test after the child's birth. The smart thing is to not assume he is until then. MANY, MANY guys have been told they were, or assumed they were... only to find out years later they weren't.

Only after its been established he is... then step up and do the right thing. The court will order it anyway. Assuming they don't get married.

How old are they both?
She is 19 and he is 21

At this time he has NO rights that can be enforceable. NONE. Later after the birth he becomes an equal, even if it takes a court order to enforce them.

As noted, he has no rights until the child is born. However, he should check to see if MO has a putative father's registry to forestall the child being given up for adoption.

What I would suggest is that he goes to the girl and her parents. That he explains to them that since it is believed the child is his, that he expects to be a part of the child's life. Tell them that as soon as the child is born he will go to court to enforce his rights. But that he would rather be a part of the child's life starting right away. And that he would prefer their cooperation for the child's sake.

As noted, he has no rights at all, at this point and time. The women's family has no rights what so ever. The baby has no rights at this time. The only person who has any rights is the mother, all of the choices are hers at this point and time.

If the mother does not want him at the doctor, he can not go. If mother wants an abortion, he can not stop it.

After the child is born, he can file for partial custody or visitation and arrange proper child support though the courts.