The Robson Ten Group Classification in all 50 states and the District of Columbia · 2016–2024 · observed rates, not predictions
Each square is one state, placed roughly where it sits on the map. Click a square, a row in the table, or a name in the ranking to open that state’s full ten-group profile.
Same data as Compare states. This page draws on exactly the counts behind Compare states: CDC WONDER, Natality 2016–2024 expanded, mother’s state of legal residence, because the natality public use file carries no geography. Hospital births to residents of the 50 states and the District of Columbia, gestational age from the obstetric estimate valid at 17 to 47 weeks, 2016 to 2024 pooled: pregnancies. Women whose presentation, previous cesarean or parity was not stated are carried as Unclassified rather than dropped, so every state’s group sizes and contributions add to its whole.
The unit is the pregnancy, not the baby. A twin pregnancy is one record, taken at the delivery of the last-born, so it counts as a cesarean if either baby was delivered abdominally. WONDER collapses set order at “3rd or higher”, so a quadruplet or higher-order set can contribute more than one record; that is roughly 40 sets a year nationally.
Three measures. Cesarean rate in group is cesareans divided by deliveries within the group. Size of group is the group’s deliveries as a per cent of all the state’s deliveries. Contribution is the group’s cesareans divided by all the state’s deliveries, in percentage points; across the groups it adds up to the state’s overall cesarean rate. A state can sit high on the map for a group because the group is large there, because its cesarean rate is high, or both; switching between the three measures separates the two.
Suppression. CDC WONDER suppresses any count of one to nine births. Suppressed cells are excluded rather than imputed, so a figure carrying the ▲ mark is a lower bound on the count behind it, understated by at most nine births per suppressed cell. This matters only for small groups in small states.
Group 9. The birth certificate offers only “Other” for presentation, which conflates transverse and oblique lie with face and brow, so the observed rate in group 9 is lower than a pure abnormal-lie group would give. Labour onset. Induction and trial of labour are tick boxes completed differently from state to state; between-state differences in groups 1 to 4 partly reflect how those boxes are filled in, not only practice.
Suggested citation. Centers for Disease Control and Prevention, National Center for Health Statistics. National Vital Statistics System, Natality on CDC WONDER Online Database. Data are from the Natality Records 2016–2024. Accessed 29 August 2026.