Birth · C-section
Robson 10-Group C-Section Classification
WHO global standard for comparing C-section rates by 10 obstetric groups. Identifies where hospitals can improve. NICE NG121. Plus what affects C-section rates and your informed choices.
Last reviewed 2 June 2026
Robson 10-group CS classification
WHO global standard for CS rate audit
Parity
Prior caesarean delivery?
Gestational age
Fetal presentation
Number of fetuses
Onset of labour
Answer all 6 questions to see the Robson group.
Educational tool only. The Robson classification is used at hospital/system level to audit and compare CS rates. WHO 2017 Implementation Manual is the operational standard. It is not a personal CS decision tool — but understanding which group you fall into can help interpret published CS rates in context.
What does this mean?
The Robson 10-Group Classification (2001) is the global standard (WHO 2015, FIGO 2016) for auditing caesarean section rates fairly. Every pregnancy belongs to exactly one group based on six characteristics: parity, prior CS, GA, onset of labour, presentation, and number of fetuses. The system lets you compare hospital A to hospital B without comparing apples to oranges — the same overall CS rate can mean very different things depending on case mix. Typical CS rate by group in high-income systems: Group 1 (low-risk nullips, spontaneous labour) should be ≤ 10 %; Group 5 (any previous CS) usually contributes the largest single chunk of overall CS, with a typical CS rate of 50–90 % (varies by VBAC uptake). Knowing your group can help you interpret CS rates in context and choose providers/units with good Group-specific outcomes.
What is Robson classification?
International standard for classifying C-section rates by 10 groups based on obstetric characteristics. WHO 2015 global standard. Identifies which groups drive total rate; informs quality improvement.
The 10 groups
- Nulliparous, single cephalic, ≥37 wk, spontaneous labour.
- Nulliparous, single cephalic, ≥37 wk, induced or pre-labour C-section.
- Multiparous (no previous C-section), single cephalic, ≥37 wk, spontaneous labour.
- Multiparous (no previous C-section), single cephalic, ≥37 wk, induced or pre-labour C-section.
- Previous C-section, single cephalic, ≥37 wk.
- Nulliparous, single breech.
- Multiparous, single breech.
- Multiple pregnancies.
- Single, transverse or oblique lie.
- Preterm (<37 wk) single cephalic.
Why use Robson groups?
- Standardises comparison.
- Identifies groups with highest C-section rates.
- Groups 1, 2, 5 typically drive most.
- Detects outliers.
- Measures change after interventions.
What’s a healthy C-section rate?
WHO 2015: “no specific rate; should be based on individual need”. UK national ~32%; varies 20-40% between trusts. Context matters — high-risk populations need more.
Why rates are rising globally
- Maternal choice.
- Previous C-section (Group 5 large).
- Rising obesity + medical complications.
- Older maternal age.
- Multiple pregnancies (IVF).
- Litigation concerns.
- Hospital practice variation.
C-section emergency categories
- Category 1 (crash): immediate threat — within 30 min.
- Category 2: compromise not immediately life-threatening — within 75 min.
- Category 3: stable compromise.
- Category 4: elective / planned.
C-section risks
Maternal:
- Bleeding more than vaginal.
- Infection.
- Thromboembolism.
- Anaesthesia risks.
- Adhesions affecting future pregnancies.
- Placenta accreta in future pregnancies (rises with each).
- Slower recovery.
- Breastfeeding initial delays.
- Possible PTSD / emotional impact.
Baby:
- Respiratory difficulties (TTN even at term).
- Breastfeeding delays.
- Gut microbiome differences.
Maternal request C-section (CMR)
Allowed UK NHS per NICE NG121. Informed decision-making: consultant discussion, risks/benefits, mental health considerations, documented. Specialist mental health support for tokophobia.
VBAC option
Trial of labour after C-section possible (~60-80% success). Both ERCS + VBAC reasonable. Informed choice. See /calculators/vbac-success.
Future pregnancy implications
- Placenta accreta: 0.3% after 1 C-section → 6.7% after 5+.
- Placenta praevia.
- Uterine rupture in next pregnancy (~0.5%).
- Adhesions.
Different scenarios
Scenario 1: First-time mum, term, spontaneous labour, no complications
Group 1. Most births aim for vaginal. C-section rate in this group should be moderate (10-15% typically).
Scenario 2: Previous C-section, term, planning birth
Group 5. ERCS vs VBAC discussion. NICE-supported informed choice.
Scenario 3: Twin pregnancy 36 wk
Group 8. Often C-section but vaginal delivery possible if twin 1 cephalic + skilled team.
Scenario 4: Breech presentation at 37 wk first baby
Group 6. ECV offered first. If unsuccessful, ERCS usually; some centres support vaginal breech with skilled team.
Scenario 5: Preterm 32 wk severe PE
Group 10. C-section often chosen for safety; vaginal possible in selected stable cases.
Care guidance — C-section decisions
- Informed choice essential.
- Ask hospital’s C-section rate by Robson group.
- VBAC option if previous C-section.
- ECV for breech.
- Doula / continuity midwife model can reduce avoidable C-sections.
- Birth debrief if emergency C-section traumatic.
- Future family size affects C-section accumulated risk.
- Mental health support for tokophobia.
Sources
- Robson MS. Classification of caesarean sections. Fetal Matern Med Rev 2001.
- WHO. Robson Classification: Implementation Manual 2017.
- NICE NG121. Caesarean birth.
- Hannah ME, et al. Term Breech Trial. Lancet 2000.
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Frequently asked questions
What is the Robson classification?
INTERNATIONAL STANDARD for classifying C-section rates by 10 GROUPS based on obstetric characteristics. CREATED by Michael Robson 2001. ADOPTED by WHO 2015 as global standard. PURPOSE: comparing C-section rates between hospitals + countries + over time; identifying which groups drive total rate; informing quality improvement. 10 MUTUALLY EXCLUSIVE GROUPS based on: parity, previous C-section, gestation, fetal lie/presentation, type of labour (spontaneous, induced, pre-labour C-section).
What are the 10 Robson groups?
GROUP 1: nulliparous (first baby), single cephalic, ≥37 wk, spontaneous labour. GROUP 2: nulliparous, single cephalic, ≥37 wk, induced or pre-labour C-section. GROUP 3: multiparous (previous baby), no previous C-section, single cephalic, ≥37 wk, spontaneous labour. GROUP 4: multiparous, no previous C-section, single cephalic, ≥37 wk, induced or pre-labour C-section. GROUP 5: previous C-section, single cephalic, ≥37 wk. GROUP 6: nulliparous, single breech. GROUP 7: multiparous, single breech (including previous C-section). GROUP 8: multiple pregnancies. GROUP 9: single, transverse or oblique lie. GROUP 10: preterm (<37 wk) single cephalic.
Why use Robson groups?
(1) STANDARDISES comparison between hospitals/countries; (2) IDENTIFIES which groups have HIGHEST C-section rates — focus improvement; (3) GROUPS 1, 2, 5 typically drive most C-sections; (4) DETECT outliers — hospital with high Group 1 C-section may have inappropriate management; (5) MEASURES change over time + after interventions; (6) ENABLES audit + feedback. WHO RECOMMENDS Robson reporting for all maternity units globally. NHS UK reports nationally + by trust.
What's a healthy C-section rate?
WHO previously suggested 10-15% optimal — REVISED 2015: 'no specific rate; should be based on individual need'. CONTEXT MATTERS: high-risk populations need more C-sections; healthy populations less. UK NATIONAL ~32% (2023); varies 20-40% between trusts. SOME COUNTRIES very high (Brazil ~55%; Egypt ~52%); others lower. EVERY C-SECTION has risks + benefits — appropriate INDICATIONS matter more than absolute rate.
Why are C-section rates rising?
GLOBAL TREND. CONTRIBUTORS: (1) MATERNAL CHOICE — preferences for planned birth; (2) PREVIOUS C-section (Group 5 contributes large amount); (3) RISING obesity + medical complications; (4) OLDER maternal age; (5) MULTIPLE pregnancies (IVF related); (6) LITIGATION concerns; (7) PERCEIVED safety; (8) CULTURAL factors; (9) HOSPITAL practice variation. NHS UK rate from ~9% (1980s) to ~32% (2023). NICE / RCOG support informed choice + reducing avoidable C-sections.
What's an 'unnecessary' C-section?
CONTROVERSIAL — context-dependent. POTENTIAL examples: (1) FIRST-STAGE diagnosis of 'failure to progress' before adequate time / techniques; (2) FETAL DISTRESS based on CTG concerning without confirmation; (3) MATERNAL request without thorough discussion of alternatives; (4) BREECH presentation without trial of vaginal breech (in selected cases); (5) Big baby suspected without confirming with ultrasound. EVERY birth different; CLINICAL judgment essential. RIGHT to refuse + right to consent both important.
What about VBAC (vaginal birth after C-section)?
Group 5 (previous C-section) drives many subsequent C-sections. ELECTIVE REPEAT C-SECTION (ERCS) common. TOLAC (trial of labour after C-section) leading to VBAC possible — ~60-80% success. Both options reasonable. NICE NG121 supports informed choice. /calculators/vbac-success for detail. INFLUENCES Robson Group 5 rates: hospitals encouraging VBAC have lower C-section rates in this group.
Does this affect my birth plan?
POTENTIALLY YES. AWARENESS that hospital practices vary; can ask about: (1) C-section rate by Robson group at your hospital; (2) VBAC success rates if applicable; (3) FETAL MONITORING approach; (4) MOBILITY / position support; (5) INDUCTION protocols. INFORMED CHOICE important. SOME WOMEN choose maternity unit based on practices. DOULA / midwife continuity model associated with lower C-section rates without compromised safety.
What are C-section risks?
(1) MATERNAL: bleeding (more than vaginal); infection; thromboembolism (DVT/PE); anaesthesia risks; bladder/bowel injury (rare); ADHESIONS affecting future pregnancies; PLACENTA ACCRETA in future pregnancies (rises with each); HYSTERECTOMY rare; slower recovery (6-8 weeks vs 2-4 weeks); breastfeeding initial delays; emotional impact / PTSD possible. (2) BABY: respiratory difficulties (TTN, even at term); breastfeeding delays; gut microbiome differences (research). C-SECTION life-saving when indicated but not 'safer' across the board.
What about emergency vs elective C-section?
CATEGORY 1 (CRASH): IMMEDIATE threat to mum/baby (cord prolapse, severe distress, abruption) — birth within 30 minutes. CATEGORY 2: maternal/fetal compromise not immediately life-threatening — within 75 minutes. CATEGORY 3: maternal/fetal compromise stable. CATEGORY 4: ELECTIVE / planned. DIFFERENT outcomes + recovery: emergency C-sections often have higher complication rates + more traumatic; planned often smoother. EMOTIONAL DEBRIEF helpful for emergency C-section experiences.
What's a vaginal breech birth?
BABY in breech presentation (bottom-down) born vaginally. OFTEN avoided since Term Breech Trial 2000 (Lancet) showed worse short-term outcomes with vaginal breech vs C-section. BUT recent evidence + skilled birth attendants in selected cases: vaginal breech outcomes similar. NICE NG121: planned C-section recommended for term breech but VAGINAL BREECH option in selected centres with experienced practitioners. ECV (external cephalic version) — turning baby — offered first. /calculators/vbac-success Group 5 context.
Can I request a C-section without medical reason?
YES — CAESAREAN MATERNAL REQUEST (CMR) allowed in UK NHS per NICE NG121. INFORMED DECISION-MAKING: (1) Discussion with consultant; (2) Information about risks/benefits both options; (3) Mental health considerations (tokophobia = fear of childbirth); (4) Decision documented. SOMETIMES specialist mental health support helps women explore reasons. SOMETIMES specific phobia / trauma history makes vaginal birth not feasible. CONSULTANT may decline if no clinical/psychological grounds, but second opinions available. /calculators/gad7-perinatal for tokophobia.
How does this affect future pregnancies?
MORE C-sections in mum's history = HIGHER RISKS in subsequent pregnancies: (1) PLACENTA ACCRETA (placenta growing into uterine scar): increasing risk with each C-section (0.3% after 1 → 6.7% after 5+); (2) PLACENTA PRAEVIA; (3) UTERINE RUPTURE in next pregnancy (rare; ~0.5%); (4) BOWEL/BLADDER injury at repeat surgery; (5) ADHESIONS. INFORMS FAMILY SIZE planning. SUBSEQUENT VBAC reduces these complications.
How does this relate to other calculators on BumpBites?
Companion: /calculators/vbac-success; /calculators/bishop-score (induction); /calculators/membrane-sweep; /calculators/birth-plan-builder; /calculators/preeclampsia-diagnosis; /calculators/gad7-perinatal (tokophobia).