Baby speech not developing

Hello,
> We have a couple of concerns about our daughter who is 15 weeks old.
> She seems to be
> developing normally in most areas but there are a couple of things
> that we are seeing recently that
> don't seem quite right. Just as background... I had a normal
> pregnancy and delivery. She makes
> eye contact and smiles at us. She can reach for a toy but is not
> interested in rolling over at this
> point.
>
> The first issue is that she seems to be vocalizing less than she was
> a month ago. She used to
> repeat vowel sounds that we made and would say "ah-goo" when we said
> it, as well. She still
> makes noises, but they aren't the consonant sounds that we expect
> and the "ah-goos" are
> completely gone.
>
> Secondly, she has begun sucking on her fingers like there is no
> tomorrow! In fact, she sucks on
> them so much that she will lie in her very dark room looking at
> nothing (we don't have a mobile or
> any toys in her crib) for a long time (perhaps an hour?) so long as
> she is sucking on her fingers.
> For instance, last night I woke up at 2:30am because that's usually
> a time that she wakes at night
> to nurse. I just went in to turn down the heat in her room and
> realized that she was awake and
> lying there sucking on her fingers. I'm not really concerned about
> her weight gain right now; she
> eats plenty during the day. Our concern stems from the fact that we
> thought that babies her age
> were supposed to be soaking in the world around them while our
> little girl seems content to lie in
> darkness with her fingers in her mouth.
>
> We don't know if these issues warrant a trip to the pediatrician.
> She is our first child an we don't
> want to be overreacting, but at the same time we want to be the best
> advocates for her that we
> can be.
>
> Any advice that you can offer would be greatly appreciated!
>
I share your concern about your daughter's regression in speech and the possible disinterest in the world around her,
I think you should see your pediatrician and that s/he should arrange a formal hearing test.
From the way that you asked your question, it appears you are concerned about developmental retardation and/or autism. While these are possible, hearing loss is much more likely but you should raise these concerns with your pediatrician as well.
I hope I am wrong about all these things but, if they are present it is important to find out as early as possible so treatment can be put in place as soon as possible.
Please let me know what happens and don't hesitate to ask more questions.
Yours sincerely