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Rising cesarean rates call for studies on which subgroups of women contribute to the rising rates, both in countries with high and low rates. This study investigated the cesarean rates and contributing groups in Iceland using the Robson 10-group classification system.This study included all births in Iceland from 1997 to 2015, identified from the Icelandic Medical Birth Registry (81 839). The Robson distribution, cesarean rate, and contribution of each Robson group were analyzed for each year, and the distribution of other outcomes was calculated for each Robson group.The overall cesarean rate in the population was 16.4%. Robson groups 1 (28.7%) and 3 (38.0%) (spontaneous term births) were the largest groups, and groups 2b (0.4%) and 4b (0.7%) (prelabor cesareans) were small. The cesarean rate in group 5 (prior cesarean) was 55.5%. Group 5 was the largest contributing group to the overall cesarean rate (31.2%), followed by groups 1 (17.1%) and 2a (11.0%). The size of groups 2a (RR 1.04 [95% CI 1.01-1.08]) and 4a (RR 1.04 [95% CI 1.01-1.07]) (induced labors) increased over time, whereas their cesarean rates were stable (group 2a: P = 0.08) or decreased (group 4a: RR 0.95 [95% CI 0.91-0.98]).In comparison with countries with high cesarean rates, the prelabor cesarean groups (singleton term pregnancies) in Iceland were small, and in women with a previous cesarean, the cesarean rate was low. The size of the labor induction group increased, yet the cesarean rate in this group did not increase.