According to the new recommendations:
"Women with a normal, uncomplicated labor may drink modest amounts of clear liquids such as water, fruit juice without pulp, carbonated beverages, clear tea, black coffee, and sports drinks. Fluids with solid particles, such as soup, should be avoided, however. Women who have uncomplicated pregnancies and are scheduled for a cesarean delivery may also drink these clear liquids up to two hours before anesthesia is administered."
It seems that the reason for limiting women to ice chips was to avoid aspiration – food and liquid entering the lungs – in the event of an emergency anesthetization. The decline of maternal death due to aspiration has lead to the new recommendations, which should be welcomed news for thirsty mamas. Were you allowed more than ice chips while birthing?