My husband and I have found ourselves in the interesting position of raising my very childish 18 year old sister. She ran away for home to live with her drug dealing meth addicted boyfriend, and we didn't see her for months, until she showed up on my doorstep and told me she was pregnant, homeless, and had left the boyfriend. She was filthy, and obviously has been abusing drugs, although I believe she has stopped since finding out she is pregnant. We are both estranged from our parents because they are extremely abusive, and I am the only family she has. I am also only 7 years older then her and she has no respect for me, my home, or my rules.
Just tonight, after my husband and I repeatedly told her that it was inappropriate for a mom to be to go to an out of town illegal rave, that we were afraid that she could be arrested and/or get hurt out of town and we wouldn't be able to get to her quickly, she lied to us and went anyway. Her excuse is always that she is 18 and an "adult". And when I tell her she can not live here and act that way she says "what are you going to do, throw me out when I am pregnant with your niece or nephew?" And of course we won't, because if we are not there to remind her of Dr appointments or to take her vitamins or not to drink caffeine, she will neglect this pregnancy.
My husband and I are so afraid that we will end up raising a child with special needs because of her lack of concern, we are already certain that we will end up raising this child anyway. We don't have children yet for a reason, we are newlyweds and just purchased our first home, we want to be enjoying the early years of our marriage, and this is something that we didn't think we would have to deal with for years. It has quickly become too much for us, but there is literally no one else to help her. Any advice is appreciated!

Tell her that she is being just like her parnets.. she's abusing this child but doesn't see it. Tell her that you WILL make her leave. Do it for a night or two . She will have to come back she pretty much has NO other choice.. I hope everything turns out well (: .

She is using you and after the child is born it will be you baby sitting while she is out party, and you buying all the baby needs, then after you get attached to the baby, she will use the baby to black mail you, you give her this or that, or you do this or that and if you don't she will move and take the baby.

Time to call her bluff and kick her out.

Not to sound like the voice of doom here, but one thing stuck out to me, actually two, but more importantly the fact that she is already using your "niece" or "nephew" as leverage.
Something that no doubt will continue.
Would your sister be open to some family counseling, in part to deal with her upbringing and to make her realize that she needs to stop that cycle now and not let it continue with her own child.

She is 18. You are not 'raising' her anymore. She is raised.

Unfortunately, though 18 is not old enough anymore to behave like an adult, legally, she IS an adult, and there is nothing to be done about it.

You make a choice.

You continue to help her and help her with her child, but ignoring the behavior you cannot control.

Or you stop helping her, and hope she learns the hard way.

Wow... this is a super tough situation. You and your new husband have big hearts... and are to be commended for trying to take such an active role in keeping your sister and her baby safe. Definitely need some boundaries here, though, so that everyone is protected...

Since you don't really have family support, maybe you should run this by a counselor, who could give you some advice about what you can/should do in this situation. It may be that you have to exercise tough love... don't know... but perhaps an outsider could give you some perspective on the situation. Do you know of a counselor, pastor or someone you trust that you can talk to about this? If you want to speak w/ a counselor over the phone, my workplace (Focus on the Family) offers a free consultation... 855-771-4357.

Also, don't know if your sister would be willing to do this (maybe only if she's desperate enough), but calling a crisis pregnancy center might be helpful to her. Often they can offer parenting classes, counseling, and support during and after the pregnancy. Maybe she'd listen better to "non-relatives"... just a thought. You can locate a center in your area by going to www.optionline.org or calling 800-712-HELP.

You have a great heart... praying for a positive outcome for all in this situation. Take care of yourself!