In this paper we present estimates of the difference in the cost of hospital care for women having different modes of singleton delivery. The estimates are based on observation of resources used in different procedures, and on data from the North West Thames Region Maternity Information System. For vaginal delivery the average cost is 363 pounds, but could fall between 189 pounds and 773 pounds, and for caesarean section the average cost is 1123 pounds, with a likely range from 837 pounds to 1560 pounds. The wide ranges in the costs of the two modes of delivery reflect variation in the length of stay and in the intensity of care required. The average cost for intrapartum care and postnatal stay is estimated to be 451 pounds for all singleton births. Variation in operative delivery rates between hospitals implies differences in the overall cost of care at different maternity units. This partly reflects differences in the needs of the population served by the units, but also differences in clinical practice. It is important for decision makers to consider the balance between the costs and outcomes of different policies of care.