I'm guessing a first-time parent? She made a very innocent/naive mistake in saying she would stay in touch with you. Brand new parents sometimes don't realize how much their life will actually change once that baby comes home. It isn't about her not caring about you; she's just in the throws of new-parenthood.

If you have her contact information, you could probably write a quick email touching base; that would probably be better than a text because she'll get to her email when she has a moment to sit still. I doubt she would be offended so long as you don't lay a guilt trip on her. She's probably just meeting herself coming and going, and a kind check-in will be fine. Be prepared; she may let you know that she realizes now that her plan to reach out to you might have been unrealistic on her part.