Original Research
Obstetrics
The introduction of a universal transvaginal cervical length screening program is associated with a reduced preterm birth rate

https://doi.org/10.1016/j.ajog.2022.07.046Get rights and content

Background

Midtrimester sonographic short cervix is a good predictor of preterm birth in singleton pregnancies.

Objective

This study aimed to assess the impact of implementing a universal transvaginal cervical length screening program on preterm birth rate.

Study Design

This study consisted of 2 parts: a before-and-after multicenter study and a study on the ECHOCOL (“echo”=“ultrasound” and “col”=“cervix” in French) prospective cohort. We compared the rate of preterm birth before and after the introduction of universal cervical length screening at the time of midtrimester anatomy ultrasound. The multicenter before-and-after regional study included all women with a singleton pregnancy who gave birth after 24 weeks’ gestation in the South East of France from January 1, 2012 to April 30, 2018. In parallel, the ECHOCOL cohort study was prospectively conducted from May 2015 to July 2018, including 17 maternity hospitals in the South East region of France. In case of asymptomatic short cervix <25 mm, treatments offered included 200 mg of vaginal progesterone, or cerclage, or a pessary until 34 weeks’ gestation.

Results

We observed a significant decrease rate of preterm birth between periods A and B after multivariate analysis. (respectively, 5.8% vs 5.6%; adjusted odds ratio, 0.92; 95% confidence interval, 0.89–0.95; P<.0001). In parallel, the percentage of cervical length screening significantly increased from 28.9% in period A to 52.9% in period B (odds ratio, 2.76; 95% confidence interval, 2.71–2.80; P<.0001). Among the 3468 patients of the ECHOCOL prospective cohort, 38 (1.1%) asymptomatic short cervices were detected, and 192 patients gave birth prematurely (11 with an asymptomatic short cervix and 181 without). In the ECHOCOL cohort, a marked but statistically insignificant tendency toward a reduced rate of preterm birth before 37 weeks of gestation was observed (from 5.8% to 5.5%; adjusted odds ratio, 0.72; 95% confidence interval, 0.51–1.03; P=.068).

Conclusion

This study showed a significantly lower rate of preterm birth after the implementation of a universal cervical length screening and treating policy during the second trimester of pregnancy. The clinical trial was registered under NCT02598323.

Introduction

Preterm birth is birth before 37 weeks of gestation.1 It can be induced or spontaneous (two-thirds of cases).2 In 2014, 14.84 million infants were born prematurely worldwide, comprising 10.6% of live births.3 In France, preterm birth represented 6% of singleton live births in 2016 (vs 4.5% in 1995).4 Preterm birth is associated with a significant increase in short- and long-term neonatal and infantile morbidity.5 Risk factors for spontaneous preterm birth are previous preterm birth, multiple gestations and abnormalities of the reproductive organs, vaginal infections, underweight or obesity before pregnancy, placenta previa, diabetes mellitus and gestational diabetes mellitus, maternal age, drug use, and smoking. Among the risk factors, a midtrimester sonographic short cervix is a good predictor of preterm birth.6, 7, 8 Thus, a previous study on asymptomatic patients with a singleton pregnancy and no history of preterm birth showed that cervical length ≤15 mm exposed them to a risk of delivery before 32 weeks of gestation of ≥50%.9 In France, cervical length screening of singleton pregnancies is recommended for women with a history of preterm birth but not systematically in other cases.1 In the United Kingdom and the United States, the National Institute for Health and Care Excellence (NICE) guidelines and the American College of Obstetricians and Gynecologists recommend midtrimester cervical length screening in case of singleton pregnancy and previous preterm birth or midtrimester loss.10,11 However, most guidelines except 2 advised against universal cervical length screening in singleton pregnancy.12,13 In the absence of previous preterm birth when an asymptomatic short cervix is detected (cervical length ≤25 mm without regular and painful uterine contractions), vaginal progesterone is recommended.1,14, 15, 16, 17 Progesterone is known for its immunomodulatory and antiinflammatory effects, and for its inhibitory effects on uterine contractions and the production of prostaglandins, responsible for cervical ripening.18 Administration of vaginal progesterone acts on the adaptive immune system by increasing the proportion of decidual CD4+ regulatory T cells.19 A 2012 meta-analysis showed that the use of vaginal progesterone in cases of singleton pregnancies with an asymptomatic short cervix significantly reduced the rate of preterm birth before 33 weeks’ gestation (12.4% vs 22.0%; odds ratio [OR], 0.58; 95% confidence interval [CI], 0.42–0.80).20 In the case of an asymptomatic short cervix with a history of preterm birth or late miscarriage, cervical cerclage is also recommended.1,15,21, 22, 23 In France, pessary is not recommended for this indication because of contradictory results concerning its efficacy. Vaginal progesterone and cerclage are equally effective in preventing preterm birth in women with a singleton gestation, previous spontaneous preterm birth, and a short cervix.15,24 However, a combination of these methods seems to give better results in reducing preterm birth rates, including those of pregnancies with a short cervix <10 mm.25 Spontaneous preterm birth with a personal history of preterm birth currently represents 10% of spontaneous preterm births in France.1 Therefore, 90% of spontaneous preterm births occur in patients without a history of preterm birth, but these are not detected because there is currently no universal cervical length screening program.26 Two retrospective studies showed that a universal cervical length screening program enabled to significantly reduce the rate of preterm birth.27,28 However, these results need to be verified in larger prospective cohorts. On this background, our study prospectively assessed the impact of a program for universal transvaginal ultrasound cervical length screening and treatment in cases of asymptomatic short cervix on the preterm birth rate, and its medical consequences.

AJOG at a Glance

To the best of our knowledge, no study has evaluated the effect of introducing a universal transvaginal cervical length screening program on the preterm birth rate in a European country.

In a before-and-after study, the introduction of a universal transvaginal cervical length screening program in the South East of France was associated with a significant reduction in the singleton preterm birth rate (from 5.8% to 5.6%; adjusted odds ratio, 0.92; 95% confidence interval, 0.89–0.95; P<.029). In the prospective cohort study (ECHOCOL), the introduction of a universal transvaginal cervical length screening program was associated with a nonsignificant decrease in the rate of preterm birth at <37 weeks’ gestation (from 5.8% to 5.5%; adjusted odds ratio, 0.72; 95% confidence interval, 0.51–1.03; P=.068).

Our study showed a decrease in the rate of preterm birth within a large cohort in France after the implementation of a universal policy of cervical length screening to identify asymptomatic short cervix and provide preterm birth preventive treatment.

Section snippets

Ethical and regulatory issues

The ethics committee provided approval on July 21, 2014 (reference number 2014-A00920-47). The ClinicalTrials.gov website was updated when ethical and regulatory approvals were obtained (identifier: NCT02598323). An informed consent form was given to the patients to harmonize the information given (research goals, procedure, benefits, and risks). All women provided informed signed consent to be included in the study. Research on the ECHOCOL prospective cohort was performed in accordance with

Comparison of period A (before) with period B (after implementation of universal screening) in the whole Mediterranean Network

Multivariate analysis of data from all the maternity hospitals belonging to the Mediterranean Network revealed that there was a significant decrease in the rate of preterm birth for singleton pregnancies from period A (5.79%; 9903 preterm births out of 171,079 births) to period B (5.6%; 9275 preterm births out of 165,524 births) (adjusted OR, 0.92; 95% CI, 0.89–0.95; P<.0001) (Table 1). We also observed a significant decrease in the rate of spontaneous preterm birth from period A (1.9%;

Principal findings

Our study showed a −0.19% significant decrease in the rate of preterm birth between periods A and B after the promotion and implementation of a policy for universal cervical length screening and treatment of asymptomatic short cervix (5.8% vs 5.6%).

Results in context

Our results are in line with previous studies (Table 4). In 2016, Son et al27 showed in a retrospective cohort of 64,207 women with singleton pregnancies that the introduction of universal cervical length screening during the second-trimester anatomy

Acknowledgments

We thank the women enrolled in the trial. In addition, we thank the Mediterranean Network, the agence régionale de santé (ARS)—regional agency of Provence-Alpes-Côte d'Azur, the 17 maternity hospitals in the network that participated in the ECHOCOL study, and the following individuals who contributed to this trial: Hervé Meur; Meriem Ait-Ouali; Marika Larose; Jean Francois Cocallemen; Michèle Marcot; Julie Blanc, MD; Nicolas Gourheux, MD; Isabelle Mortier, MD; Sandrine Lobelle, MD; Carole

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  • Cited by (3)

    The authors report no conflict of interest.

    The agence régionale de santé (ARS) regional agency supported this program (number 20140650 conv C2014000343).

    ClinicalTrials.gov identifier: NCT02598323. Date of registration: November 5, 2015. First participant enrolled on May 19, 2015. https://clinicaltrials.gov/ct2/show/NCT02598323

    Cite this article as: Figarella A, Chau C, Loundou A, et al. The introduction of a universal transvaginal cervical length screening program is associated with a reduced preterm birth rate. Am J Obstet Gynecol 2023;228:219.e1-14.

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