One case is no proof to anything, but *I am sure* that giving my third baby probiotics after birth helped tremendously. My first son had some food intolerances, my DD had true allergies and a lot of food intolerances, so I knew that I had to avoid stuff with my third one. I did not do anything during pgcy (in fact I started eating everything, including dairy and gluten, since I stopped BFing my DD as I felt really malnourished). When my third kid was born and his stools looked green and smelled like vinegar, he was always fussy, some eczema etc., I knew that I had a long road ahead of me again. I started eliminating everything from my diet, but after weeks on TED and no ``normal" stools, I reached the conclusion that this was not helping. What I did from the time he was about 4-5 weeks old (I wish I started earlier!) was to give him an allergen free probiotic (don't remember the name, was in a blue glass container, the doctor/lactation consultant that I saw recommended it). I gave him many times the recommended dose, I would just put it on the spoon and feed it to him, as much as he would take, then give him water (or I would mix it with water and give it with a dropper). I am still BF-ing him (he is 20+ months), and we are still mostly GF free, but we do eat butter, mozarella cheese, and in small amounts he is ok with these. On rare occasions I have other stuff, he usually waked up more and he is more fussy/clingy when I step off the safe route, but this way I do not feel like I am restricting myself too much. He is gaining weight *very well*, he is mostly very healthy, we had few episodes of ear infections but they always came after me eating gluten or dairy (traveling for conferences etc.).
It may not be much that you can do during pgcy, but I definitely recommend probiotics as soon after birth as you feel comfortable doing it. Body Ecology has a nice cocobiotic - a liquid that contains a very good probiotic, you can try that too (they say it is safe to give it to the baby from a couple of weeks old).
Good health to your babies!
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