Congrats on the new baby!!!
I've never had a baby, but being in the skin care biz and seeing as how there is a baby boom going on, I've seen and heard all the remedies. I would imagine that the new stuff Strivectin et al (go for the SD with spf) would be an excellent choice. The oligo-peptides (seaweeds) strengthen and heal, bilberry and licorice lighten and there are several other skin strengtheners in there. Most of the over the counter scar and stretchmark products are zinc with a few other things added. Zinc will help heal soft tissue damage and it's an absolute
must when you get back in a bathing suit as that tissue is very easily discolored by the sun. But zinc alone isn't going to lighten are lessen stretchmarks. If you are breast feeding make sure you have your dr check out the ingredients for safety etc.
Vitamin E isn't really used straight out of the capsule anymore since plastic surgeons stopped recommending it...seems it actually retards healing in some cases. But Vit E along with cocoa butter etc would a great thing to rub down with as a preventative as the tummy grows to keep the skin supple. ...but we're past that here.
There are other treatments as well if you feel that they're really bad. Cool laser and LED light therapies produce some great results without the hot laser pain. Look around at some more progressive spas in the area that may be performing these therapies and get a consultation.
Good luck!!
EDIT: a couple more points and I'll shut up
Do NOT use anything with alpha hydroxy acids that are more than about 4% and don't let someone talk you into doing a peel on them. They actually can cause inflamation within the cells that will increase the discoloration. Besides...aha's are mostly exfoliants and that tissue doesn't need exfoliation..don't know why they put it in scar trt creams
Also be aware that most 'post inflamitory hyperpigmention" (I love using big terms

) can take several months to fade...just be patient and don't over-treat the area.
Okay...that's all.