Cephalopelvic disproportion

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Cephalopelvic disproportion
Deformed female pelvis, which is at risk for cephalopelvic disproportion
SymptomsDifficult childbirth, specifically obstructed labor[1]
ComplicationsBaby: Death, cerebral palsy, brachial plexus injury[2]
Mother: Obstetrical fistula, pelvic floor dysfunction[2]
CausesSmall pelvis, large baby, malpresentation of the babies head[1][2]
Risk factorsShort (<1.60 m), rickets, prior pelvic fracture[2]
Diagnostic methodBased on symptoms, supported by medical imaging[2]
PreventionInduction of labor at 38 weeks[2]
TreatmentC-section, operative vaginal delivery, oxytocin infusion[2]
Frequency1 in 250 pregnancies[3]

Cephalopelvic disproportion (CPD) occurs when the size of the mothers pelvis, and thus birth canal, is smaller than the size of the babies head.[1] Symptoms include difficult childbirth, specifically a form known as obstructed labor.[1] Complications may include death of the baby, cerebral palsy, brachial plexus injury, obstetrical fistula, and pelvic floor dysfunction.[2]

The most common cause is a small pelvis.[1] Other causes include an overly large baby, which may occur due to hydrocephalus, thyroid tumors, or macrosomia.[2] Some also include relative size difficulties such as occur in malpresentation of the babies head.[1] Risk factors include being short (<1.60 metres (5.2 ft)), rickets, and prior pelvic fracture.[2] Diagnosis is based on symptoms such as failure of the head to decend into the pelvis and the shape of the babies head changing; though may be supported by medical imaging.[2]

Treatment often requires C-section; however, occasionally an operative vaginal delivery or oxytocin infusion maybe used.[2] Oxytocin is associated with a risk of uterine rupture.[2] Preventive efforts may include induction of labor at 38 weeks in those with large babies.[2]

Cephalopelvic disproportion occurs in about 1 in 250 pregnancies.[3] Poor outcomes are particularly common in low and middle income countries where access to expert care is often limited.[2] In high income countries some women are refusing typically recommended management options.[2] It is a relatively common reason for legal cases in obstetrics.[2]

Signs and symptoms

Symptoms include difficult childbirth.


A large fetus can be one cause of CPD. A large fetus can be caused by gestational diabetes, postterm pregnancy, genetic factors, and multiparity.[citation needed]

The shape of the pelvis can also be a cause of CPD. The pelvis may be too small, or the shape of the pelvis may be malformed.[4] Shorter women are more likely to have CPD[5] as are adolescents.[6]


Diagnosis of CPD may be made when there is failure to progress, but not all cases of prolonged labour are the result of CPD. Use of ultrasound to measure the size of the fetus in the womb is controversial, as these methods are often inaccurate and may lead to unnecessary caesarian section; a trial of labour is often recommended even if size of the fetus is estimated to be large.[4]

Theoretically, pelvimetry may identify cephalo-pelvic disproportion. However, a woman's pelvis loosens up before birth (with the help of hormones). A Cochrane review in 2017 found that there was too little evidence to show whether pelvimetry is beneficial and safe when the baby is in cephalic presentation.[7] A review in 2003 came to the conclusion that pelvimetry does not change the management of pregnant women, and recommended that all women should be allowed a trial of labor regardless of pelvimetry results.[8] It considered routine performance of pelvimetry to be a waste of time, a potential liability, and an unnecessary discomfort.[8]


In the case of a fetus being too large, some obstetricians recommend induction of labour for earlier delivery. Diagnosis of CPD in active labour will usually result in a Caesarian section.[citation needed]

See also


  1. 1.0 1.1 1.2 1.3 1.4 1.5 Skandhan, Avni K. P. "Cephalopelvic disproportion | Radiology Reference Article | Radiopaedia.org". Radiopaedia. Archived from the original on 13 February 2024. Retrieved 4 March 2024.
  2. 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 2.13 2.14 2.15 2.16 Murphy, Deirdre J. (January 2020). "Malpresentation, malposition, and cephalopelvic disproportion". Oxford Textbook of Obstetrics and Gynaecology. Oxford University Press: 395–406. doi:10.1093/med/9780198766360.003.0032.
  3. 3.0 3.1 "Cephalopelvic Disproportion (CPD)". American Pregnancy Association. 26 April 2021. Archived from the original on 1 October 2023. Retrieved 4 March 2024.
  4. 4.0 4.1 "Cephalopelvic Disproportion (CPD): Causes and Diagnosis". American Pregnancy Association. 26 April 2012. Archived from the original on 2016-03-22. Retrieved 2016-03-22.
  5. Liselele HB, Boulvain M, Tshibangu KC, Meuris S (August 2000). "Maternal height and external pelvimetry to predict cephalopelvic disproportion in nulliparous African women: a cohort study". BJOG. 107 (8): 947–52. doi:10.1111/j.1471-0528.2000.tb10394.x. PMID 10955423.
  6. McKenry, Patrick C.; Walters, Lynda Henley; Johnson, Carolyn (1979-01-01). "Adolescent Pregnancy: A Review of the Literature". The Family Coordinator. 28 (1): 17–28. doi:10.2307/583263. JSTOR 583263.
  7. Pattinson R, Cuthbert A, Vannevel V (2017-03-30). "Pelvimetry for fetal cephalic presentations at or near term for deciding on mode of delivery". Cochrane Database of Systematic Reviews. 3 (12): CD000161. doi:10.1002/14651858.CD000161.pub2. PMC 6464150. PMID 28358979. Archived from the original on 2023-04-15. Retrieved 2024-03-04.
  8. 8.0 8.1 Blackadar CS, Viera AJ (2004). "A retrospective review of performance and utility of routine clinical pelvimetry". Fam Med. 36 (7): 505–7. PMID 15243832. Archived from the original on 2023-02-20. Retrieved 2024-03-04.

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