B.B.
how much milk is she drinking? And is she eating light colored foods? I would suggest keeping a food log and keeping track of how much and what she's eating and drinking. Then if it is something Physiological you can show the DR what has been going in... I watched one little girl that was drinking just a ton of milk and her BM was whitish yellow.
Watch her for any abnormal behavior and call DR asap if you see anything that makes your mommy sense tingle...
Good luck AND congrats on the little one!!!