Dear Catherine: I located some articles on ketosis in pregnancy, but there is only one reference to the first trimester (and it was about rats!). I originally read about ketones in Nutrition and Lactation by Worthington-Roberts. As I said before, the only full-blown articles I have seen were in regard to gestational diabetes. It is quite possible that the literature on embryology would have more in it, but I am not familiar with it! I, too, would be interested in learning more. Maybe I'll get to go to the library again soon!! Martha Grodrian Brower RD LD IBCLC Ketosis, OH