The only medical advice I'm aware of is to determine the gender. It wouldn't have an effect on the mother's mood. The pregnancy books only grant the wish to read one. It doesn't do anything else for the pregnancy. Aside from just keeping her in a good mood, it's critical that she get enough rest. That means her energy must never drop to yellow or red. If you do everything else perfectly, but she gets too tired, you'll loose the chance to pick one of the traits.
When a sim is pregnant, an option opens up on the pie menu for the hospital for her to "Get Medical Advice," or something to that extent. I'm not totally sure what it does, but I had assumed that it did the same thing as reading a pregnancy book (and in light of the information you gave, perhaps it does lol). I did go once, and got charged something like $200 for the visit. I got to pick both traits for the child, but I suppose it could be coincidental.
I wonder what that does now. I'm going to have to search it out.
Edit: From what I read, getting medical advice from the hospital and reading pregnancy books adds to her "pregnancy mood" (a term I saw pop up a couple of times). I'm assuming that this
could offset some of the negative impact that lower moods and times where she doesn't get enough rest, but it's anyone's guess as to how much effect it has (or if what I've read is even true). It also mentioned that fulfilling her wishes during that time helped too, but I'm assuming that this due to nothing more than getting the "Fulfilled" moodlet that would help elevate her mood. I also saw someone say that sims could get a wish to get medical advice, but I've never had a sim generate that wish in all of the time I've played.
But if what Pam says is true (and I
do believe that it is: she has had enough sim babies to know what she's talking about lol), these extra measures wouldn't even be necessary if you're taking proper care of the mother to begin with.