my protector

maybe he senses your vulnerable state....

I'm not sure this is healthy behavior.  I would have to see it to be sure, but I would not want the dog to become protective over you in relation to the baby. 
 
I would, for the next 2-3 months, put DH in charge of the dog.  Walking, feeding, exercising, training, etc.  This will help alleviate some of the dogs tension as far as pack order is concerned. Your dog maybe having trouble seeing you as the leader during this time, and this can go very wrong very fast.  Allow DH to step in and demonstrate clear and distinct leadership to the dog.  You can be involved with the dog, of course.  But I would only to it in situations where your are in control, and that is clear to the dog.
 
I would follow this regimen until the growling subsides.

I'm no animal behaviorist, but I think he's just taken on the role of the protector, like your subject line says.  I don't think he would do any harm to your husband, you, or your baby.  Dogs can sense (and smell) changes in our body chemistry and their behavior may change because of that.  I think the growling is being used as a warning to anyone that may intend to cause harm to you, not ossessiveness.  The fact that he is staying by your side and on guard while you're sleeping is his way of making sure nothing bad happens to you or your baby.  I would not discipline your dog or change your relationship with him because of this.  I have to disagree with Mic in that I don't see this as a 'tension over pack order' problem at all.     

 

I think the growling is being used as a warning to anyone that may intend to cause harm to you

 
Amylu
Growling is a "warning to anyone" that what is about to happen?  If it is a warning, that means you believe something is going to follow it.
 
I do think that this will continue to progress, and could quickly end up as a resource guarding issue. 
 
Think about it like this...If this were a 100 pound dog would you take action?  I know I would. 
 

I would not discipline your dog 

 
I would not discipline the dog either.  But I do think that you have to take back the control.  It is not your dogs job to protect you...he is not genetically prepared to handle this task, and this WILL lead to behavior problems. 
 

I'm definitely a little worried.  Like I said, he is the sweetest thing.  As soon as he finds out what or who the noise is, he's fine, tail wagging, happy as can be, even if he doesn't know the person.  The oil guy was just here.....Sam heard him come in the door, started to growl (burped while he was growling, the funniest sound) but then as soon as he saw that it was a person, he was happy and wagging his tail.  I can't even imagine him ever hurting a person but I guess this change in behavior has me a little on edge with the baby coming.  Part of me also thinks that he is also just copying one of our other dogs behavior, who barks at every little noise AND bites anyone that he comes into contact with that he doesn't know.  (This is my sister in laws maltese, she lives upstairs)  My dog hasn't seen him bite people but he is definitely an aggressive dog.  Also, my husband seems to think it's great that he has started growling or barking at strange noises.  He encourages it.  While I feel better knowing that he'll growl if someone is breaking into the house, I'm not so sure we should encourage it!  It's almost as if the behavior itself, the growling, suprises even the dog!  Tonight when he heard my brother in law come home, he heard the door open upstairs, he started to growl.  He was barely growling and not even for that long and it seemed to overwhelm him, he started panting and running around like he didn't know what he was feeling or how to handle it.  ???

Mic.....you mention that I need to take back the control.  I'm just wondering, what may have happened to cause this switch in control?  Why does he suddenly think HE'S in control?  I love the idea of a watch dog but I don't want him to be possessive of me or anyone in this house in particular.  He was just in bed with my husband and I had to go in and get him because he was crying.  When he knows I'm awake, he has to be with me.  He won't growl or get agressive to get what he wants, he just cries until I go in and pick him up.  (He's too small to jump off the bed/it's too high).  Now he's sound asleep in his little bed next to me.  When I'm finished online, I'll tell him it's time for bed, and we'll go in together, and he'll fall asleep instantly tucked into my pregnant belly.  I hope it's just a case of him loving me rather than a developing behavioral problem! 

In reference to the example you gave about him crying in the bed and you had to come pick him up to make him stop...
 
Who do you think controlled that situation?  It was not you...
 
He seems to be able to get you to do what ever he would like with a little bit of whining.  You should not be responding to the crying unless he is in some sort of real danger.
 
I would start of by ignoring the crying until he is quiet, and if you want to pick him up or do something for him he needs to do something for you first.  I recommend having him sit, and wait a few seconds before you pick him up.  This is called deferment.  I would expect your dog to sit and wait a few seconds before you do ANYTHING for him.  this includes feeding, PETTING, going outside, coming in, pretty much anytime you interact with him.
 
Teaching the dog to deffer to you is the key to getting things under control.
 
I have included a link to a case study that relates to some degree.  This is what can happen if the dog is not treated.
 
It is not exactly the same but you will see the similarities.
 
[linkhttp://dvm.adv100.com/dvm/article/articleDetail.jsp?id=15787]http://dvm.adv100.com/dvm/article/articleDetail.jsp?id=15787[/link]

Thanks for the help!