When a Scan Shows a Short Cervix: Which Treatments Help Keep a Baby Inside Longer?

A plain-language guide to Wu et al.'s 2026 BMJ Medicine review comparing progesterone, a cervical stitch and a cervical ring for women who have not had an early baby before

When a pregnancy scan shows that the cervix is shorter than usual, the baby has a higher chance of being born early. A review that combined 26 studies, covering more than 6,000 women, found that a daily vaginal progesterone medicine remains the best-proven way to lower that chance. Using two treatments together looked promising but was tested in too few women to be sure, and none of the options clearly changed how babies did after birth.

If you have been told that your cervix is short, or your baby is now in a neonatal unit after an early birth, you may be wondering what could have been done, or what might be offered next time. This article explains what one large new review found, what it could not tell us, and why doctors still recommend the approach they do.

Why a short cervix matters and how doctors learned to treat it

The review at the centre of this article, published in 2026 by Wu and colleagues in the journal BMJ Medicine, asked a question many families share: when a short cervix is found in a woman who has never had an early baby, which treatment works best [1]? To see why that question matters, it helps to start with the cervix itself. The cervix is the narrow neck at the bottom of the womb. During pregnancy it normally stays long and firmly closed until labour begins. Around the middle of pregnancy, an internal ultrasound scan (a small probe placed in the vagina) can measure its length, and a cervix that is shorter than usual is a warning sign that the baby may come early.

Being born early, or "preterm", means arriving before 37 weeks of pregnancy instead of around 40. It is common: about 13.4 million babies, roughly 1 in 10 of all babies born worldwide, arrived preterm in 2020 [2]. Complications of being born early were also the leading cause of death in children under five in 2019 [3]. Women who have already had an early baby are much more likely to have another [4], so doctors watch them closely. But most early births before 34 weeks happen to women who have never had an early baby before, and for them a short cervix on a scan is one of the best warning signs doctors can measure [5].

For more than 20 years, doctors have tested three main ways to help. The first option was progesterone, a hormone that the body naturally makes in pregnancy. In a large study coordinated by the Fetal Medicine Foundation, which screened more than 24,000 women in several countries, 250 women with a very short cervix placed either a progesterone medicine or a dummy look-alike (a placebo) in the vagina each night. Of those using progesterone, about 19 in every 100 gave birth before 34 weeks, compared with about 34 in every 100 of those using the dummy [6]. A second study across several countries, using a progesterone gel, found a similar benefit and fewer breathing problems in babies [7].

The second option was a cervical stitch, called a cerclage, which a doctor places around the cervix to help keep it closed. The third was a cervical pessary, a soft silicone ring placed around the cervix. The pessary story has had many twists. An early study called the Pesario Cervical para Evitar Prematuridad (PECEP) trial, in five hospitals in Spain, found a dramatic benefit: early births before 34 weeks fell from 27 in every 100 to 6 in every 100 [8]. But a later, large study in the United States, called TOPS, run at 12 hospitals in a national research network, found that the ring did not reduce early births. It was stopped early, partly because more babies died before or after birth in the pessary group: about 13 in every 100, compared with about 7 in every 100 [9]. Since then, the Society for Maternal-Fetal Medicine, a United States organisation of specialists in high-risk pregnancy, has recommended progesterone for a short cervix and advised against the ring, and against a stitch for most of these women [5].

What was still missing was a fair way to compare all of these choices, including using two together, specifically in women who had never had an early baby before.

What the researchers did

In 2026, a team of doctors from hospitals in China, Spain and Japan, led by Wu, published a review that gathered the results of every suitable study they could find [1]. They used a method called a network meta-analysis. In everyday terms, it works a little like a sports league table. Not every team plays every other team, but by combining all the results, you can still estimate how each team would fare against the others and rank them.

The review found 26 studies, all of the kind called randomised trials, in which women were assigned by chance to one treatment or another. Together these studies had enrolled 8,561 women, but the researchers used the 6,004 women who met the review's definition of no earlier very early birth (before 32 weeks). They compared progesterone given vaginally, a weekly progesterone-like injection, a stitch, a ring, and a stitch or ring combined with vaginal progesterone, against no treatment, a dummy treatment or usual care. Some of these studies compared treatments directly. Quadruple P, run at 20 hospitals and five scan clinics in the Netherlands, compared the ring with progesterone [10], and the Stitch, Pessary, or Progesterone Randomised Trial (SuPPoRT), at 19 hospital maternity units in the United Kingdom, compared all three [11].

What they found

The clearest finding was about vaginal progesterone on its own. In the studies that compared it directly with no treatment, it lowered the chance of a baby being born before 34 weeks by about 44%, and the researchers rated this evidence as high quality [1]. Put in everyday numbers, the review's model suggested that out of every 100 women with a short cervix, about 19 would give birth before 34 weeks without treatment, compared with about 12 using vaginal progesterone.

When all the treatments were ranked together, the ring combined with progesterone came out on top, and in the model it lowered early births before 34 weeks to about 7 in every 100. The stitch combined with progesterone came second, and progesterone alone came third. That sounds as though combinations are better, but there is an important catch. Only 332 women in all the studies had received the ring plus progesterone, and just 43 had received the stitch plus progesterone, all of them in one small study that was stopped early [12]. Results from so few women can easily change when more are studied.

Combinations also came with more side effects for mothers. Women using progesterone alone had fewer side effects than those using the ring plus progesterone [1]. Most side effects were not dangerous; with the ring-based treatments, the most common was extra vaginal discharge. In one Italian study, about 87 in every 100 women with a ring noticed discharge, compared with about 46 in every 100 without one [13].

What it means for babies

For parents, the most important question is whether these treatments help babies be healthier. Here the honest answer is that we do not yet know. For outcomes such as a baby dying around the time of birth, needing admission to a neonatal intensive care unit, having breathing problems, infections, bleeding in the brain or a serious bowel illness, none of the treatments made a clear difference compared with no treatment [1]. This does not mean they do nothing. Some of these problems, such as baby deaths, bleeding in the brain and serious bowel illness, were rare in the studies (only 19 cases of bleeding in the brain and 29 of serious bowel illness were recorded), so even a large review did not have enough babies to detect a difference with confidence. Progesterone showed a slight leaning towards fewer baby deaths, but the evidence was too uncertain to be sure.

What families can take from this

If your cervix has been found to be short and you have not had an early baby before, this review supports what US specialist guidance already recommends: daily vaginal progesterone is the best-proven first step. The researchers suggest that using two treatments together should, for now, be offered only as part of a research study. They mention the ring as a possible alternative for some women who cannot use progesterone, but the Society for Maternal-Fetal Medicine advises against it [5], and the TOPS study found more baby deaths in the ring group [9], so it is worth asking your care team about the risks and benefits for you.

It also helps to know that treatment lowers the chance of an early birth but does not remove it. If your baby does arrive early, that is not a sign that you or your doctors did something wrong. Neonatal teams care for many babies born after their mothers received progesterone or other treatments, and they will explain what to expect for your baby's particular gestation.

What researchers are working on next

Researchers want to know whether combined treatments really help babies, not just whether they delay birth, and which women benefit most depending on how short the cervix is. An international project called the PROspective Meta-analysis of Pessary Trials (PROMPT) is pooling the detailed results of individual women from many pessary studies to answer these questions for the cervical ring more clearly [14]. An earlier review covering a wider group of high-risk women also found that vaginal progesterone was the best-supported option [15], so the overall picture has been steady for several years.

If you would like to read more, In[Neo]Sight has published articles on what different kinds of studies tell us about the cervical ring and on whether every pregnant woman should have her cervix measured. For now, this new review gives families and doctors a reassuringly clear message: daily vaginal progesterone remains the most trustworthy choice when a short cervix is found, and newer combinations need more study before they become routine.

References

  1. Wu H, Yu L, Zhang J, et al. Progestogens, cervical cerclage, and cervical pessary for preventing preterm birth in asymptomatic singleton pregnancies with a sonographic short cervix and no previous history of spontaneous preterm birth: systematic review and bayesian network meta-analysis. BMJ Med. 2026;5(1):e003010. doi:10.1136/bmjmed-2026-003010 ↩
  2. Ohuma EO, Moller AB, Bradley E, et al. National, regional, and global estimates of preterm birth in 2020, with trends from 2010: a systematic analysis. Lancet. 2023;402(10409):1261-1271. doi:10.1016/S0140-6736(23)00878-400878-4) ↩
  3. Perin J, Mulick A, Yeung D, et al. Global, regional, and national causes of under-5 mortality in 2000-19: an updated systematic analysis with implications for the Sustainable Development Goals. Lancet Child Adolesc Health. 2022;6(2):106-115. doi:10.1016/S2352-4642(21)00311-400311-4) ↩
  4. Yang J, Baer RJ, Berghella V, et al. Recurrence of Preterm Birth and Early Term Birth. Obstet Gynecol. 2016;128(2):364-372. doi:10.1097/AOG.0000000000001506 ↩
  5. Biggio J. SMFM Consult Series #70: Management of short cervix in individuals without a history of spontaneous preterm birth. Am J Obstet Gynecol. 2024;231(2):B2-B13. doi:10.1016/j.ajog.2024.05.006 ↩
  6. Fonseca EB, Celik E, Parra M, Singh M, Nicolaides KH. Progesterone and the risk of preterm birth among women with a short cervix. N Engl J Med. 2007;357(5):462-469. doi:10.1056/NEJMoa067815 ↩
  7. Hassan SS, Romero R, Vidyadhari D, et al. Vaginal progesterone reduces the rate of preterm birth in women with a sonographic short cervix: a multicenter, randomized, double-blind, placebo-controlled trial. Ultrasound Obstet Gynecol. 2011;38(1):18-31. doi:10.1002/uog.9017 ↩
  8. Goya M, Pratcorona L, Merced C, et al. Cervical pessary in pregnant women with a short cervix (PECEP): an open-label randomised controlled trial. Lancet. 2012;379(9828):1800-1806. doi:10.1016/S0140-6736(12)60030-060030-0) ↩
  9. Hoffman MK, Clifton RG, Biggio JR, et al. Cervical Pessary for Prevention of Preterm Birth in Individuals With a Short Cervix: The TOPS Randomized Clinical Trial. JAMA. 2023;330(4):340-348. doi:10.1001/jama.2023.10812 ↩
  10. van Dijk CE, van Gils AL, van Zijl MD, et al. Cervical pessary versus vaginal progesterone in women with a singleton pregnancy, a short cervix, and no history of spontaneous preterm birth at less than 34 weeks' gestation: open label, multicentre, randomised, controlled trial. BMJ. 2024;384:e077033. doi:10.1136/bmj-2023-077033 ↩
  11. Hezelgrave NL, Suff N, Seed P, et al. Comparing cervical cerclage, pessary and vaginal progesterone for prevention of preterm birth in women with a short cervix (SuPPoRT): A multicentre randomised controlled trial. PLoS Med. 2024;21(7):e1004427. doi:10.1371/journal.pmed.1004427 ↩
  12. Boelig RC, Tersigni C, Di Simone N, et al. Cerclage in singleton pregnancies with no prior spontaneous preterm birth and short cervix: a randomized controlled trial. Am J Obstet Gynecol MFM. 2025;7(4):101602. doi:10.1016/j.ajogmf.2025.101602 ↩
  13. Saccone G, Maruotti GM, Giudicepietro A, Martinelli P. Effect of Cervical Pessary on Spontaneous Preterm Birth in Women With Singleton Pregnancies and Short Cervical Length: A Randomized Clinical Trial. JAMA. 2017;318(23):2317-2324. doi:10.1001/jama.2017.18956 ↩
  14. Thom EA, Saade GR, Askie LM, et al. PROMPT: Prospective Meta-analysis for Pessary Trials Study Protocol. Am J Perinatol. 2024;41(S 01):e2230-e2237. doi:10.1055/s-0043-1771018 ↩
  15. Care A, Nevitt SJ, Medley N, et al. Interventions to prevent spontaneous preterm birth in women with singleton pregnancy who are at high risk: systematic review and network meta-analysis. BMJ. 2022;376:e064547. doi:10.1136/bmj-2021-064547 ↩