Soy is actually a huge No.
My number 1 source is Dr.Mercola, Who is famous for being into alternative health, Natural foods and remedies. I have been subscribed to his website for a long time. There are a ton of videos and articles. Just a ton of information about what is best to eat, and what is worst. If you'd like to, i reccomend you subscribe to his website.
Here is a video about Soy products. Dr.Mercola is a FREE website, full of information.
I trust his opinions and research very much, at first i was skeptical of his work, but after double researching everything he said i now know that his information is very credible.
If I followed everything on that site, I would be in perfect health.
The Truth About Soy Foods
And if this isn't enough - here is a direct link to the part that is more of a direct answer to your question.
* Danger during pregnancy and nursing
Link Between High Soy Diet During Pregnancy and Nursing and Eventual Developmental Changes in Children
The only exception is Fermented soy products.
Here is an article about fermented vs nonfermented =
Soy Bad, Soy Good: The Pluses of Fermented Soy 8/4/04
I know this is a lot of stuff to read, but there is just so much information you should know before you make the choice. Please read this and watch the video in the top link...before you eat any unfermented soy products.