Preterm labour and birth

It is 23:40 and a 29-week primigravida is tightening every four minutes. She is frightened, the cervix is 2 cm and soft, and your hospital has a special care nursery but no neonatal intensive care. Everything that matters in the next hour is decided by three questions: is she really in labour, is there a reason she must deliver now, and can you get her somewhere better before the baby comes. Get those three right and the drugs almost prescribe themselves.^[2][19]

For the undergraduate-level overview of preterm labour, see the MBBS page on preterm labour. This topic assumes it and goes to consultant depth.^[2]

Overview and definition

Preterm birth is birth before 37+0 weeks. Preterm labour is a clinical diagnosis you have to earn: regular uterine contractions plus documented cervical change. Contractions alone are not the diagnosis, and treating them as though they were is how units burn magnesium, beds and helicopter hours on women who were never going to deliver.^[2][15]

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Two framings help at the station. Tempo: threatened preterm labour (symptoms, uncertain outcome) versus established preterm labour (progressive cervical change, birth is coming). Route: spontaneous preterm labour, preterm prelabour rupture of membranes, and provider-initiated preterm birth for a maternal or fetal indication. Each route has a different prevention strategy and a different conversation.^[2][20]

References20ShowHide

1. [1]Stock SJ, Thomson AJ, Papworth S, et al. Antenatal corticosteroids to reduce neonatal morbidity and mortality: Green-top Guideline No. 74 BJOG, 2022.PMID 35172391
2. [2]American College of Obstetricians and Gynecologists Practice Bulletin No. 171: Management of Preterm Labor Obstet Gynecol, 2016.PMID 27661654
3. [3]McGoldrick E, Stewart F, Parker R, Dalziel SR Antenatal corticosteroids for accelerating fetal lung maturation for women at risk of preterm birth Cochrane Database Syst Rev, 2020.PMID 33368142
4. [4]Gyamfi-Bannerman C, Thom EA, Blackwell SC, et al. Antenatal Betamethasone for Women at Risk for Late Preterm Delivery N Engl J Med, 2016.PMID 26842679
5. [5]Crowther CA, Haslam RR, Hiller JE, Doyle LW, Robinson JS Neonatal respiratory distress syndrome after repeat exposure to antenatal corticosteroids: a randomised controlled trial Lancet, 2006.PMID 16765760
6. [6]Walters A, McKinlay C, Middleton P, Harding JE, Crowther CA Repeat doses of prenatal corticosteroids for women at risk of preterm birth for improving neonatal health outcomes Cochrane Database Syst Rev, 2022.PMID 35377461
7. [7]Oladapo OT, Vogel JP, Piaggio G, et al. Antenatal Dexamethasone for Early Preterm Birth in Low-Resource Countries N Engl J Med, 2020.PMID 33095526
8. [8]Shepherd ES, Goldsmith S, Doyle LW, Middleton P, Marret S, et al. Magnesium sulphate for women at risk of preterm birth for neuroprotection of the fetus Cochrane Database Syst Rev, 2024.PMID 38726883
9. [9]Crowther CA, Hiller JE, Doyle LW, Haslam RR Effect of magnesium sulfate given for neuroprotection before preterm birth: a randomized controlled trial JAMA, 2003.PMID 14645308
10. [10]Rouse DJ, Hirtz DG, Thom E, Varner MW, Spong CY, et al. A randomized, controlled trial of magnesium sulfate for the prevention of cerebral palsy N Engl J Med, 2008.PMID 18753646
11. [11]Crowther CA, Ashwood P, Middleton PF, McPhee A, Tran T, Harding JE Prenatal Intravenous Magnesium at 30-34 Weeks' Gestation and Neurodevelopmental Outcomes in Offspring: The MAGENTA Randomized Clinical Trial JAMA, 2023.PMID 37581672
12. [12]Wilson A, Hodgetts-Morton VA, Marson EJ, Markland AD, Larkai E, et al. Tocolytics for delaying preterm birth: a network meta-analysis (0924) Cochrane Database Syst Rev, 2022.PMID 35947046
13. [13]van Vliet EOG, Nijman TAJ, Schuit E, Heida KY, Opmeer BC, et al. Nifedipine versus atosiban for threatened preterm birth (APOSTEL III): a multicentre, randomised controlled trial Lancet, 2016.PMID 26944026
14. [14]King JF, Flenady V, Papatsonis D, Dekker G, Carbonne B Calcium channel blockers for inhibiting preterm labour; a systematic review of the evidence and a protocol for administration of nifedipine Aust N Z J Obstet Gynaecol, 2003.PMID 14712983
15. [15]Stock SJ, Horne M, Bruijn M, White H, Heggie R, et al. A prognostic model, including quantitative fetal fibronectin, to predict preterm labour: the QUIDS meta-analysis and prospective cohort study Health Technol Assess, 2021.PMID 34498576
16. [16]Iams JD, Goldenberg RL, Meis PJ, Mercer BM, Moawad A, et al. The length of the cervix and the risk of spontaneous premature delivery N Engl J Med, 1996.PMID 8569824
17. [17]EPPPIC Group Evaluating Progestogens for Preventing Preterm birth International Collaborative (EPPPIC): meta-analysis of individual participant data from randomised controlled trials Lancet, 2021.PMID 33773630
18. [18]Alfirevic Z, Milan SJ, Livio S Caesarean section versus vaginal delivery for preterm birth in singletons Cochrane Database Syst Rev, 2013.PMID 24030708
19. [19]Gordon HG, Shub A, Stewart MJ, Kane SC, Cheong JL, et al. In-utero transfer, survival-focused care and survival to 28-days at 22-24 weeks' gestation pre- and post- implementation of an extreme prematurity management guideline in Victoria, Australia BMJ Paediatr Open, 2024.PMID 39433430
20. [20]Chawanpaiboon S, Vogel JP, Moller AB, Lumbiganon P, Petzold M, et al. Global, regional, and national estimates of levels of preterm birth in 2014: a systematic review and modelling analysis Lancet Glob Health, 2019.PMID 30389451