Well, my last 'fetus' (now nearly 36 yr. old) didn't make me crave carbs at all. What I did crave was fresh herbs, like mint and parsley and basil which I grazed on in the garden!

We ate lots of farm fresh food- raised our own beef and chickens, had an organic garden, and milked a cow.

I think my four kids are really fortunate having had such a good source of healthy food, and back then we didn't even realize how lucky we were (despite the fact we ate far too many "healthy" grains along with the home-grown stuff).

I really miss having home grown beef, homemade butter from our own milk, and free range chickens producing beautiful bright-yolked eggs. What I don't miss is milking the dang cow! For our summers we still have home grown veggies and berries, so that is good.

First, babies are naturally in ketosis for some time after they're first born--even if the mother is on a carb-rich diet herself.

There is zero nutritional requirement for carbs. Look at the Inuits as an example.

For Paleolithic people, how would it be possible for mothers to have healthy children if ketosis was harmful? It would have been a frequent state back then, since food intake was often sporadic.

In fact, infant brain and nervous system health is probably more determined by adequate saturated fat intake, and harmed by not getting enough!

This is anecdotal, but I am a type 1 diabetic who had a healthy, happy baby last year, following the Bernstein diet. My husband's obstetrician cronies told him I would starve the baby or make her retarded by being in ketosis, but guess what?? They were wrong. Plus, apparently everyone gets ketogenic during a long overnight fast -- even normal women. I brought this up once and was told I would have to get up in the middle of the night and eat to prevent that. Ridiculous!

I think it's pretty clear that ketosis could be tolerated, after all, since HGs would clearly have had to not eat regular carbohydrate containing meals on occasion. Anything that mimics normal human non-eating is bound to be tolerable, but plausibly even pseudo-starvation and pregnancy wouldn't go well together. Since I'm suspicious as to whether (deep) ketosis would be optimal anyway, my intuition would be that something approaching the Optimal Diet would be optimal for pregnancy too (i.e. just enough carb to be slightly out of ketosis, give the brain (and possibly the growing foetus) an easy source of energy, while running most processes on fat.) Plausibly this moderate low carb diet would maintain the benefits of keeping carb and insulin low, while still signalling to the body that there are comfortable amounts of food around. There's been a lot written about stress/starvation/LC versus fertility/plenty/HC, so perhaps higher levels of carb would be preferable during pregnancy as well. Assuming that pregnant women only need about an extra 200 calories per day for the first 6 months or so, then presumably we're not looking at massive extra amounts.

Since we're in very vague, person-specific hand-waving territory here, as to amounts, I'd probably just reassert my feeling that pregnancy is probably analogous to increased activity levels: increased carbohydrate being far better tolerated and possibly optimal for recovery and growth.

Interesting question, but I haven't seen any studies on it. Clearly, it's not desirable for a woman to have high blood sugar while pregnant. There are many studies on mothers with gestational diabetes (eg. http://linkinghub.elsevier.com/retrieve/pii/S0002937803019276 ). When the mother is diabetic, it affects the glucose and free fatty acids that cross the placenta, among other things. Infants of diabetic mothers are at risk for a host of complications in the newborn period, including respiratory distress, LOW blood sugar, birth defects, overweight, high hemoglobin, low calcium, and heart failure. My own bias would be for a pregnant woman to keep everything as "normal" as possible during pregnancy, including her weight and blood sugar. I don't know whether or not ketosis is dangerous to the baby.

Doesn't the fact that we're both here having this conversation answer the question? :-)