Daisymae said ... You don't condone her behaviour yet you facilitate it by constantly having her children so that she can be footloose. I wonder if it time to pull back and let her shoulder the responsibility. She has made her choices.
I agree with Daisymae ... you are facilitating your daughter's behaviour. She is the mother of two young boys, and needs to act more responsibly. I can understand that what you are doing, you are doing out of love for your daughter and grandchildren, but it's really not helping in the long run.
You loan her money, bail her out when she's in trouble, and have the grandchildren most weekends to enable her to go out and behave promiscuously. She now finds herself in this difficult situation, and no doubt thinks that mum will come to the rescue and make it all alright again.
Adult child, or not, I'd be having a serious talk with her and leave her in doubt that whilst I love her very much, and I will always be here for her, but I am very disappointed with the way she conducts her life, and the situation she now finds herself in. I'd tell her that's it's time she grew up, and acted like a responsible mother, as those two little boys deserve better.
I'd support her with whatever decision she makes about the pregnancy, but I'd tell her in no uncertain terms that things need to change. It is not your responsibility to continually bail out your daughter ... when will it all end? Probably never, if you continue to do it ...