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Robson Ten-Group Classification

Also called Robson classification, TGCS, caesarean section audit, WHO Robson

Places any woman admitted for birth into one of the 10 mutually exclusive WHO Robson groups (with the common 2a/2b, 4a/4b, 5.1/5.2 subdivisions).

Parity and previous caesarean

Earlier miscarriages do not count; uterine scars from myomectomy do not count as previous CS.

Number of fetuses
Final lie / presentation before decision for delivery or diagnosis of labour
Gestational age at admission
Onset of labour

Spontaneous labour later augmented with oxytocin or amniotomy is still "spontaneous".

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Formula and scoring

Order of decisions: multiple → 8; transverse/oblique → 9; breech → 6 (nullipara) or 7 (multipara); cephalic <37 weeks → 10; cephalic ≥37 weeks: previous CS → 5 (5.1 one, 5.2 two or more); nullipara → 1 (spontaneous) or 2 (2a induced, 2b pre-labour CS); multipara without CS → 3 or 4 (4a/4b).

Exam and ward pearls

  • Groups 1, 2 and 5 together normally contribute about two-thirds of all caesareans in most hospitals (WHO manual).
  • WHO proposes the Robson classification as the global standard for assessing, monitoring and comparing caesarean section rates within and between facilities.
  • Previous myomectomy alone does not put a woman in Group 5 — only CS scars count.

When not to rely on it

  • It is an audit tool for groups of women, not a clinical risk score for an individual.
  • Women with missing core variables are "unclassifiable" and must be reported separately; state your definition of a birth (weight / gestation cut-off) in the report.

Source

  1. World Health Organization. Robson Classification: Implementation Manual. Geneva: WHO; 2017 (Tables 2–3 and frequent questions). Link

Formula and cut-offs checked against these sources on 8 Nov 2026. Educational tool for clinicians; it does not replace clinical judgement.

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