Caffeine consumption in small amounts (less than 200 mg/day) during pregnancy does not seem to be associated with miscarriage or preterm birth. However, caffeine’s effect on the growth of the fetus is not known. (34)
Caffeine and diabetes:
Caffeine may increase blood glucose levels by lowering insulin sensitivity. Lowering insulin sensitivity makes insulin less effective at lowering blood glucose levels.
Drinking caffeinated coffee with meals may decrease insulin sensitivity, according researchers.Ten healthy men 5 mg/kg of caffeinated coffee one hour before eating a meal (75-g oral glucose load) with either a high glycemic index (Crispex) — comprised of foods that raise blood sugar levels quickly, such as processed carbohydrates — or a low glycemic index meal (All Bran). Caffeinated coffee before a high glycemic index meal resulted in significant insulin sensitivity reduction of 40% compared to decaffeinated coffee before the same meal. Caffeinated coffee prior to a low glycemic index meal led a 29% decrease in insulin sensitivity than the same meal eaten after consuming decaffeinated coffee. (22)