Oxytocin and carbetocin after childbirth: the peptides that prevent bleeding

The problem: bleeding after birth

After a baby and placenta are delivered, the womb must contract hard to clamp the blood vessels where the placenta was attached. When it does not, bleeding can be fast and heavy. A 2026 review estimates that postpartum haemorrhage occurs in about 27 million women a year, 17 million after vaginal birth and 10 million at caesarean, and that about 43,000 women die from it annually, a death every 12 minutes. It is the leading cause of maternal death worldwide, and the commonest cause is a womb that fails to contract, called uterine atony (review) ¹.

Who is at risk, and the new definition

Any woman can haemorrhage after birth, but the 2026 review lists the main risk factors: caesarean birth, multiple pregnancy, anaemia, high BMI, a previous haemorrhage, pre-eclampsia, a very large baby, sepsis and inadequate antenatal care. Beyond death, consequences include severe anaemia, hysterectomy, organ failure and lasting psychological trauma, and the estimated global economic burden is about US$10.4 billion a year (review) ¹.

WHO has recently redefined haemorrhage to catch it earlier: objectively measured blood loss of at least 300 ml with an abnormal sign such as a racing pulse or low blood pressure, or at least 500 ml, whichever comes first (review) ¹. Measuring rather than estimating blood loss is part of the change, because visual estimates tend to miss the early stage when treatment works best.

Oxytocin: the standard

Oxytocin is a nine-amino-acid peptide hormone made in the brain and released during labour and breastfeeding. Given by injection, it makes the womb contract, which is why it is used both to induce or strengthen labour and to prevent bleeding after birth. In the US it is marketed as Pitocin for antepartum and postpartum use (dataset) ². Our oxytocin entry covers its other research, including the nasal spray studies that have not held up.

Oxytocin has one weakness that matters enormously in poor countries: it breaks down in heat. A 2018 review of the research landscape noted that heat degradation is one of the key reasons oxytocin can fail to prevent haemorrhage (review) ³. Where refrigeration and transport are unreliable, a vial may hold less active drug than its label says.

Carbetocin: a longer-acting relative

Carbetocin is a synthetic analogue of oxytocin, modified to last longer. A heat-stable formulation was developed so that it could be stored without a fridge; a 2025 review describes it as stable for up to three years at 30°C or below (review) ⁴. In the UK it is authorised as Pabal, given as a single 100 µg dose after delivery, and it is on WHO's Model List of Essential Medicines; it has no FDA approval (dataset) ². Its label dose is a single 100 µg injection after delivery (dataset) ², which suits busy or under-resourced labour wards where an infusion is harder to run. Our carbetocin entry has the details.

The CHAMPION trial

CHAMPION was designed to answer one question: is heat-stable carbetocin at least as good as oxytocin? It enrolled 29,645 women having vaginal births at 23 sites in 10 countries and gave each an intramuscular injection of carbetocin 100 µg or oxytocin 10 IU, with both drugs refrigerated so that the comparison was fair and blinded. Blood loss of at least 500 ml or the need for an additional uterotonic drug occurred in 14.5% on carbetocin against 14.4% on oxytocin (relative risk 1.01), which met the trial's test of non-inferiority. For severe bleeding of at least 1,000 ml, rates were 1.51% against 1.45%, but non-inferiority could not be shown because severe bleeding was too rare to measure precisely. Other interventions and side effects did not differ (randomised trial) ⁵.

The importance of the result lies in the refrigeration detail. Keeping both drugs cold removed the one advantage carbetocin was designed to have, so the trial tested the drugs themselves on equal terms. Under ideal conditions the two drugs performed alike, which means that in places where oxytocin is likely to have degraded, a drug that does not degrade should do better in practice.

What the reviews conclude

The 2025 Cochrane network meta-analysis of uterotonics pooled 122 trials with 121,931 women from 48 countries. All agents except injectable prostaglandins prevented bleeding of 500 ml or more compared with placebo; carbetocin had similar effects to oxytocin, on high-certainty evidence, and made little or no difference compared with oxytocin for bleeding of 1,000 ml or more. The two highest-ranked options were combinations: ergometrine plus oxytocin and misoprostol plus oxytocin (network meta-analysis) ⁶.

Some analyses suggest advantages in particular settings. A Bayesian meta-analysis of 30 trials found carbetocin reduced the need for additional uterotonics after caesarean (relative risk 0.43) and in high-risk vaginal births, and reduced transfusion (meta-analysis) ⁷. A meta-analysis focused on vaginal birth found no significant difference and concluded the choice would depend on cost-effectiveness (meta-analysis) ⁸.

Heat-stable carbetocin in practice

The 2025 review of heat-stable carbetocin in low- and middle-income countries collected programme experience. In a Nigerian pilot covering 18,364 deliveries, 56% of women received heat-stable carbetocin and the recorded haemorrhage rate fell to 0.8%; programmes in Kenya and South Sudan reached over 90% coverage with training, pooled purchasing and designated 'PPH champions'; and an Indian cost model estimated it could prevent about 5,500 additional haemorrhages and save five maternal lives per 100,000 births if priced comparably to oxytocin (review) ⁴. Community work mattered too: in Kenya, awareness of uterotonics and of the danger signs of haemorrhage among new mothers rose from 48% to 81% after a community programme (review) ⁴. These are programme reports and models rather than randomised comparisons, but they show how a stable drug, combined with training and supply systems, changes what is possible.

WHO's 2025 postpartum haemorrhage guideline recommends carbetocin for all births and heat-stable carbetocin where the oxytocin cold chain cannot be maintained (dataset) ².

A small difference worth noting

Not every secondary finding favours carbetocin. In a nested CHAMPION study of 1,799 women at one site in southern India, blood loss did not differ, but haemoglobin two to three days after birth was very slightly lower after carbetocin than oxytocin (10.09 against 10.21 g/dL) (randomised trial, substudy) ⁹. A difference that small is unlikely to matter clinically, but it is a reminder that "non-inferior" means close, not identical. It also shows the value of nested studies: a single large trial can carry smaller measurements, like haemoglobin, that the main outcome would not capture, and report them honestly even when they lean the other way.

At caesarean

Bleeding risk is higher at caesarean birth, where the 2026 review puts haemorrhage prevalence at about 31% under the conventional definition (review) ¹. Lower doses may suffice in low-risk cases: in 277 women having planned caesareans under spinal anaesthesia, carbetocin 20 µg produced uterine tone non-inferior to the standard 100 µg, and low-dose oxytocin was likewise non-inferior to the standard dose, with similar blood loss and side effects (randomised trial) ¹⁰.

Oxytocin in labour: dose matters

Oxytocin is also used to strengthen labour, where the evidence shows its double edge. Across eight trials with 3,154 women, high doses shortened labour by about an hour but did not reduce caesarean births, while low doses caused less over-stimulation of the womb (meta-analysis) ¹¹. In another trial, continuing an oxytocin infusion through active labour more than doubled fetal heart-rate abnormalities compared with stopping it (51% against 20%) and increased uterine hyperstimulation (12% against 2%), at the cost of a 41-minute longer labour when it was stopped (randomised trial) ¹². Used well, oxytocin saves lives; used carelessly, it can harm mother and baby, which is why it is given under monitoring, with the dose adjusted to the strength of contractions and the baby's heart rate rather than set once and left.

When prevention fails: tranexamic acid

Uterotonics prevent haemorrhage; when bleeding happens anyway, treatment adds other drugs. The most important is tranexamic acid, which slows the breakdown of blood clots. In the WOMAN trial of 20,060 women with postpartum haemorrhage, it reduced death from bleeding from 1.9% to 1.5% (risk ratio 0.81), and more so when given within three hours of birth (1.7% to 1.2%), although it did not reduce hysterectomy or the combined outcome of death or hysterectomy (randomised trial) ¹³. Tranexamic acid is not a peptide, but it sits beside oxytocin and carbetocin in the bundle of care that saves lives, and the 2025 review notes that combining heat-stable carbetocin with tranexamic acid and other bundle elements further improved outcomes in programmes (review) ⁴.

When there is no injection: misoprostol

Where no trained person can give an injection, misoprostol, an oral tablet that also makes the womb contract, has been used for prevention. The 2025 Cochrane review rated the evidence for misoprostol alone as very low certainty and found it may be less effective than oxytocin for preventing severe bleeding (risk ratio 1.24) (network meta-analysis) ⁶. Heat-stable carbetocin, which still needs an injection but no fridge, fills a different gap: places where trained staff exist but reliable refrigeration does not.

Carbetocin beyond childbirth

Carbetocin has also been tested as a nasal spray for the extreme hunger of Prader-Willi syndrome, a rare genetic condition. In a phase 3 trial of 130 participants aged 7 to 18, stopped early by the COVID-19 pandemic, neither main endpoint reached significance at the higher dose, though the lower 3.2 mg dose showed nominally significant improvements in hunger, anxiety and distress, and flushing was the commonest side effect (randomised trial) ¹⁴. It is not approved for that use, and it is a reminder that a peptide proven for one job is not automatically useful for another.

Not the 'bonding hormone' sold online

Oxytocin is often marketed online as a 'love hormone' nasal spray for bonding, anxiety or social confidence. That has nothing to do with its proven medical use. Nasal oxytocin is not FDA-approved, and controlled trials in conditions such as Prader-Willi syndrome and autism have been disappointing (dataset) ²; our article on the oxytocin nasal spray studies explains how the early excitement failed to replicate.

Why carbetocin is not used everywhere

If carbetocin works as well as oxytocin and keeps without a fridge, why is oxytocin still the default in rich countries? Mainly cost and need. Where cold chains are reliable, oxytocin's heat sensitivity matters little, and the vaginal-birth meta-analysis concluded that the choice between them would come down to cost-effectiveness (meta-analysis) ⁸. The Scottish Medicines Consortium, for example, did not recommend Pabal for NHS Scotland in 2017 (dataset) ². The 2025 review's Indian cost model makes the same point from the other side: the benefit depends on carbetocin being priced comparably to oxytocin (review) ⁴.

A short timeline

• 2017: the WOMAN trial shows tranexamic acid reduces deaths from bleeding when given early (randomised trial) ¹³.
• 2018: CHAMPION shows heat-stable carbetocin is non-inferior to oxytocin in 29,645 women (randomised trial) ⁵.
• 2019: carbetocin joins WHO's Model List of Essential Medicines (dataset) ².
• 2021 to 2022: meta-analyses suggest advantages at caesarean (meta-analysis) ⁷, and low doses prove enough for planned caesareans (randomised trial) ¹⁰.
• 2025: the Cochrane network meta-analysis of 122 trials confirms carbetocin and oxytocin are similar (network meta-analysis) ⁶, and WHO's guideline recommends heat-stable carbetocin where cold chains fail (dataset) ².

Questions to ask your midwife or obstetrician

• Which drug will I be given after the birth to prevent bleeding, and when?
• Do I have risk factors for heavy bleeding, such as anaemia or a previous haemorrhage, and what is the plan if bleeding starts?
• Will my blood loss be measured rather than estimated?
• If I am being induced or my labour strengthened with oxytocin, how will the baby's heart rate be monitored?

Quick glossary

• Postpartum haemorrhage (PPH): heavy bleeding after birth, now defined by WHO from measured blood loss.
• Uterotonic: a drug that makes the womb contract, such as oxytocin, carbetocin, ergometrine or misoprostol.
• Uterine atony: a womb that fails to contract after birth, the commonest cause of PPH.
• Cold chain: the unbroken refrigeration a drug like oxytocin needs from factory to patient.
• Non-inferior: shown to be not meaningfully worse than the comparison, within a margin set in advance.

Why this matters beyond medicine

Most peptide stories on this site involve research compounds with thin evidence. This one is the opposite: two peptide hormones with some of the largest trials in obstetrics, a public-health problem that kills a woman every 12 minutes, and a practical engineering fix, heat stability, that matters more than any small difference in effect. It is a useful reminder of what rigorous evidence for a peptide looks like: large randomised trials, independent reviews, programme data from the places that need it most, and guidelines that change when the evidence does.

How it adds up (as of October 5, 2026)

Oxytocin, injected after birth, is the standard way to prevent postpartum haemorrhage, which kills an estimated 43,000 women a year. Its weakness is heat, which matters most where refrigeration is least reliable. In the 29,645-woman CHAMPION trial, heat-stable carbetocin was non-inferior to refrigerated oxytocin on the main outcome, though not shown non-inferior for severe bleeding, and the 2025 Cochrane review found the two similar. Carbetocin is not FDA-approved but is on WHO's Essential Medicines List, and WHO's 2025 guideline recommends heat-stable carbetocin where the cold chain cannot be maintained. Oxytocin sprays sold online for bonding are a different and unsupported use, and they should not be confused with the medicine given on a labour ward.

Frequently asked questions

Is carbetocin better than oxytocin?

In the 29,645-woman CHAMPION trial, heat-stable carbetocin was non-inferior to oxytocin for blood loss of 500 ml or more (14.5% vs 14.4%); its main advantage is that it does not need refrigeration.

Why does heat stability matter?

Oxytocin breaks down in heat, so where refrigeration is unreliable a dose may be weaker; heat-stable carbetocin stays stable without a fridge.

Is carbetocin approved in the US?

No. It has no FDA application, but it is authorised in the UK as Pabal and is on WHO's Model List of Essential Medicines.

How common is postpartum haemorrhage?

An estimated 27 million women a year experience it and about 43,000 die, making it the leading cause of maternal death worldwide.

Does oxytocin nasal spray help bonding?

Nasal oxytocin is not FDA-approved, and controlled trials of it have been disappointing; its proven use is injection around childbirth.

Related on Grey Peptides

• Oxytocin
• Carbetocin
• Oxytocin nasal spray studies
• Peptides in IVF

Sources

1. Coomarasamy, A., et al. (2026). Postpartum haemorrhage: epidemiology, consequences, and missed opportunities. Lancet, 408(10549), 62-73. PMID: 42285119
2. Grey Peptides dataset rows for oxytocin (Pitocin, NDA 018261, antepartum and postpartum use; label effective May 5, 2026) and carbetocin (no FDA application on Drugs@FDA, read September 30, 2026; UK Pabal SmPC, 100 µg once after delivery, updated August 6, 2025; WHO Model List of Essential Medicines since 2019; 2025 WHO PPH guideline recommendation; Scottish Medicines Consortium, December 2017).
3. Theunissen, F. J., et al. (2018). Current research on carbetocin and implications for prevention of postpartum haemorrhage. Reprod Health, 15(Suppl 1), 94. PMID: 29945640
4. Adnani, Q. E. S., et al. (2025). Heat-Stable Carbetocin in the Management of Postpartum Haemorrhage in Low- and Middle-Income Countries: A Comprehensive Review of Clinical Evidence, Cost-Effectiveness, Implementation Challenges and Adoption Strategies. Int J Womens Health, 17, 1615-1630. PMID: 40487679
5. Widmer, M., et al. (2018). Heat-Stable Carbetocin versus Oxytocin to Prevent Hemorrhage after Vaginal Birth. N Engl J Med, 379(8), 743-752. PMID: 29949473
6. Gallos, I. D., et al. (2025). Uterotonic agents for preventing postpartum haemorrhage: a network meta-analysis. Cochrane Database Syst Rev, 4(4), CD011689. PMID: 40237648
7. Kalafat, E., et al. (2021). Efficacy of carbetocin in the prevention of postpartum hemorrhage: a systematic review and Bayesian meta-analysis of randomized trials. J Matern Fetal Neonatal Med, 34(14), 2303-2316. PMID: 31537134
8. Jin, X. H., et al. (2019). Carbetocin vs oxytocin for prevention of postpartum hemorrhage after vaginal delivery: A meta-analysis. Medicine (Baltimore), 98(47), e17911. PMID: 31764790
9. Vernekar, S. S., et al. (2022). Effect of heat stable carbetocin vs oxytocin for preventing postpartum haemorrhage on post delivery hemoglobin-a randomized controlled trial. J Matern Fetal Neonatal Med, 35(25), 8744-8751. PMID: 34763599
10. McDonagh, F., et al. (2022). Carbetocin vs. oxytocin at elective caesarean delivery: a double-blind, randomised, controlled, non-inferiority trial of low- and high-dose regimens. Anaesthesia, 77(8), 892-900. PMID: 35343585
11. Aboshama, R. A., et al. (2021). High dose vs. low dose oxytocin for labor augmentation: a systematic review and meta-analysis of randomized controlled trials. J Perinat Med, 49(2), 178-190. PMID: 32950965
12. Bor, P., et al. (2016). Continuation versus discontinuation of oxytocin infusion during the active phase of labour: a randomised controlled trial. BJOG, 123(1), 129-35. PMID: 26309128
13. WOMAN Trial Collaborators. (2017). Effect of early tranexamic acid administration on mortality, hysterectomy, and other morbidities in women with post-partum haemorrhage (WOMAN): an international, randomised, double-blind, placebo-controlled trial. Lancet, 389(10084), 2105-2116. PMID: 28456509
14. Roof, E., et al. (2023). Intranasal Carbetocin Reduces Hyperphagia, Anxiousness, and Distress in Prader-Willi Syndrome: CARE-PWS Phase 3 Trial. J Clin Endocrinol Metab, 108(7), 1696-1708. PMID: 36633570

Educational information, not medical advice. Each dose in this guide names its source, an approved label or a published study. None is a recommendation for you. An unapproved compound has no established safe or effective human dose, and products sold for “research use only” are not made or tested for people. Talk to a doctor before acting on anything on this site, including before you start, stop or change any medicine or dose.