Table 2 Characteristics of included studies reporting on an individual clinic
Study details | Characteristics of women cared for in the clinic and spontaneous preterm birth rate | Eligibility criteria for referral to the clinic | Investigations and interventions offered | Timing and frequency of review |
|---|---|---|---|---|
1. Bolt 2011 Retrospective observational study. 12 month period, dates not reported. Guys and St Thomas’ Hospital, London, UK. Primary and secondary outcome data also obtained from Min 2016, Khambay 2012 and Duhig 2009. | 147 women; White 45%, Black 44%, Asian 4%, other 5% and unknown 3%. Risk factors for spontaneous preterm birth: previous preterm birth > 24 weeks 37%, previous late miscarriage 35%, LLETZ 13%, cone biopsy 11%, previous cerclage 16%, current cerclage 27%. Spontaneous preterm birth rate < 37 weeks 18%. | Previous preterm birth < 37 weeks. Previous PPROM < 37 weeks. Previous late miscarriage 16–24 weeks. Extensive cervical surgery e.g. LLETZ, cone biopsy, trachelectomy. Uterine abnormality. Cervical length < 25 mm on transvaginal scan. Previous cervical cerclage. | Investigations: - Transvaginal cervical length ultrasound scans. - Quantitative fFN at 22–30 weeks. Interventions: Cervical cerclage: offered electively if ≥ 3 previous spontaneous deliveries or losses at 16–34 weeks or ≥ 2 with an additional risk factor, a previous failed cerclage, or as an ultrasound-indicated procedure if cervical length is < 20 mm on transvaginal ultrasound. If considered high risk based on cervical length and fFN results at 23–28 weeks: - Hospital admission. - Antibiotics if infection suspected. - Tocolysis (nifedipine) if contracting. - Betamethasone. | Timing of planned first visit not reported. Women are seen 2–6 weekly, individualised to clinical need. Women assessed as low risk are discharged at 22–24 weeks. High risk woman are seen up to 30 weeks. |
2. Ivandic 2018 Retrospective audit. January 2013 – December 2017. Liverpool Women’s Hospital, Liverpool, UK. Primary and secondary outcome data also obtained from Care AG 2014 and Alfirevic 2013. | 129 women; White 85%, Black African 3%, Asian 2%, Arab 3% and other 7%. Risk factors for spontaneous preterm birth: previous preterm birth or PPROM < 34 weeks 76%, LLETZ 21%, knife cone biopsy 9%. Spontaneous preterm birth rate < 37 weeks 50%, < 34 weeks 29%. | Previous spontaneous preterm birth at 16–34 weeks. Previous PPROM at 16–34 weeks. Significant cervical surgery defined as ≥ 2 LLETZ or knife cone biopsy. Uterine abnormalities. Incidental finding of short cervix on ultrasound. Following an episode of threatened preterm labour. | Investigations: - Transvaginal cervical length ultrasound scans. Interventions: Treatment is offered if transvaginal cervical length < 3rd centile for gestational age, including: - Cervical pessary. - Vaginal progesterone. - Cervical cerclage. | The first visit is planned for 16 weeks, or earlier if there is a history of significant cervical surgery or cerclage in a previous pregnancy. Women are seen 1–4 weekly depending on the initial cervical length and the gestational age of previous preterm births. Women are discharged at 28 weeks. |
3. Karkhanis 2012 Retrospective audit. November 2007 – November 2009. Birmingham Heartlands Hospital, Birmingham, UK. Primary and secondary outcome data also obtained from Raouf 2009. | 180 women; ethnicity not reported. Risk factors for spontaneous preterm birth: previous preterm labour or mid-trimester loss 88%. Spontaneous preterm birth rate < 37 weeks 32%. | Previous preterm birth. Previous mid-trimester loss. | Investigations: - Transvaginal cervical length ultrasound scans. - Midstream urine. - Low vaginal swabs. Interventions: - Cervical cerclage. - Vaginal progesterone. - Combined treatment. | The first visit is planned for 16 weeks. Frequency of review is not reported. Women are discharged at 34 weeks. |
4. Yulia 2015 Retrospective audit (conference abstract only). January 2011 – December 2013. Chelsea and Westminster Hospital, London, UK. | 63 women; ethnicity not reported. Risk factors for spontaneous preterm birth: previous late miscarriage or preterm delivery < 34 weeks 40%, previous deep cervical treatment 43%, uterine anomaly 8%. Spontaneous preterm birth rate < 37 weeks 16%. | Previous preterm delivery < 34 weeks. Previous late miscarriage. Previous deep cervical treatment. Uterine anomalies. | Investigations: - Transvaginal cervical length ultrasound scans. Interventions: - Cervical cerclage. | Not reported. |
5. Kindinger 2013 Retrospective audit (conference abstract only). January 2011 – January 2013. St Mary’s Hospital, London, UK. | 160 women; ethnicity not reported. Risk factors for spontaneous preterm birth: previous cervical treatment 43%, previous preterm birth < 34 weeks 21%, previous mid-trimester loss 26%, uterine anomalies 5%, multiple pregnancy 3%. Spontaneous preterm birth rate < 34 weeks 8%. | Previous preterm birth < 34 weeks. Previous mid-trimester loss. Previous cervical treatment. Uterine anomalies. Multiple pregnancy. | Investigations: - Transvaginal cervical length ultrasound scans. Interventions: - Vaginal progesterone. - Cervical cerclage. | Not reported. |
6. Burul 2014 Retrospective audit (conference abstract only). January 2005 – December 2012. University College London Hospital, London, UK. | 125 women; ethnicity and risk factors for spontaneous preterm birth not reported. Spontaneous preterm birth rate not reported, but median gestation at delivery was 35+ 2 weeks. | Not reported. | Investigations: - Not reported. Interventions: - Cervical cerclage. | Not reported. |
7. Grant 2016 Prospective observational study (conference abstract only). January 2014 – January 2016. Royal Derby Hospital, Derby, UK. | 146 women; ethnicity not reported. Risk factors for spontaneous preterm birth: previous preterm birth < 37 weeks 36%, previous second trimester miscarriage 13%, previous failed rescue cerclage 1%, previous LLETZ 49%, previous cone biopsy 2%, previous cervical biopsies 2%, medical history (not further defined) 4%. Spontaneous preterm birth rate < 37 weeks 25%. | Previous preterm birth < 37 weeks. Previous second trimester miscarriage. Previous failed rescue cerclage. Previous LLETZ. Previous cone biopsy. Previous cervical biopsies. Medical history (not further defined). | Investigations: - Transvaginal cervical length ultrasound scans. Interventions: - Vaginal progesterone. - Cervical cerclage. | Not reported. |
8. O’Brien 2010 Qualitative interpretive study. Study dates not reported. Manchester, UK. | 14 women; White British 93%, Black Caribbean 7%. Risk factors for spontaneous preterm birth and spontaneous preterm birth rate not reported. | Previous preterm birth. Cervical surgery or other gynaecological procedures that increases the risk of cervical incompetence (not further defined). | Investigations: - Transvaginal cervical length ultrasound scans. Interventions: - Cervical cerclage. - Vaginal progesterone. - Aspirin. - Antibiotics. - Activity restriction. - Hospital admission. | Timing of planned visit is not reported, however it is noted that women are encouraged to attend as soon as they become pregnant. Frequency of review is weekly, fortnightly or monthly depending on individual needs. Timing of last visit is not reported. |
9. Turitz 2016 Cross-sectional study. November 2009 – June 2013. Hospital of the University of Pennsylvania, Pennsylvania, United States of America. | 218 women; African American 83%, Caucasian 12%, other 6%. Risk factors for spontaneous preterm birth: previous second trimester loss 39%, previous spontaneous preterm birth < 37 weeks 71%. Spontaneous preterm birth rate < 37 weeks 36%. | Previous spontaneous preterm birth < 37 weeks. Previous second trimester loss 16–24 weeks. | Investigations: - Transvaginal cervical length ultrasound scans. Interventions: - IM 17OHP-C for all. - Cervical cerclage also recommended if cervical length ≤ 15 mm or previous preterm birth < 34 weeks. | Not reported. |
10. Manuck 2011 Retrospective cohort study. Usual care patients June 2002 – June 2010, preterm birth clinic patients 2008–2010. Utah, United States of America. | 70 preterm birth clinic patients; Caucasian 83%. (153 usual-care patients). Risk factors for spontaneous preterm birth: previous spontaneous preterm birth < 35 weeks 100%. Spontaneous preterm birth rate < 37 weeks 49% in preterm birth clinic patients (63% in usual care patients). | Previous spontaneous preterm birth < 35 weeks. | Investigations: - Transvaginal cervical length ultrasound scans. - Vaginal swab for bacterial vaginosis. - Urine culture. - fFN only if symptoms. Interventions: - IM 17OHP-C for all. - Cervical cerclage if cervical length < 25 mm at < 22 weeks. If cervical length shortening is detected > 22 weeks: - Hospital admission. - Activity restriction. - Tocolysis (indomethacin) if contracting. - Betamethasone. | The first visit is planned for 10–18 weeks. Frequency of review is six weekly with additional visits as clinically indicated (every 1–2 weeks if the cervix shortens). Women are discharged at 28–32 weeks. |
11. Hughes 2017 Retrospective audit. 2004–2013. Royal Women’s Hospital, Melbourne, Australia. | 756 women; ethnicity not reported. Risk factors for spontaneous preterm birth: previous spontaneous preterm birth 54%, previous cervical surgery 24%, uterine malformations 11%, incidental finding of short cervix 9%. Spontaneous preterm birth rate < 37 weeks 21%. | Previous spontaneous preterm birth. Previous mid-trimester loss. Previous cervical surgery: ≥1 cold knife cone biopsy or ≥ 2 LLETZ. ≥3 surgical terminations of pregnancy or ≥ 4 dilatation and curettage procedures. Incidental finding of a short cervix < 25 mm on transvaginal scan in the mid-trimester. Uterine malformation. | Investigations: - Transvaginal cervical length ultrasound scans. - Cervical swabs for abnormal flora at each visit and for chlamydia at the first visit. - Serum thyroid stimulating hormone and alkaline phosphatase at the first visit. - fFN at the final visit. Interventions: Women are offered treatment if cervical length < 25 mm, options include: - Vaginal progesterone. - Cervical cerclage. - Arabin pessary (as part of a study only). Appropriate antimicrobials as indicated. | The first visit is planned for 14 weeks. Women are seen fortnightly. Women are discharged at 26 weeks. |
12. Newnham 2017 Prospective population-based cohort study. 2009 – December 2015 (November 2014 – December 2015 for assessment of preterm birth clinic) Perth, Western Australia. | 154 women cared for in the preterm birth clinic, but data on 92 concluded pregnancies reported only (233,527 births in whole statewide cohort); ethnicity not reported. Risk factors for spontaneous preterm birth: previous early preterm birth 67%, recurrent pregnancy losses 26%, previous cone biopsy or other ablative procedures of the cervix 14%, uterine anomalies 11%, autoimmune conditions 11%, placental risk factors 10%. Preterm birth < 37 weeks 32% (spontaneous preterm birth rate not reported separately). | Previous early preterm birth. Recurrent pregnancy loss. Previous cone biopsy or other ablative procedure of the cervix. Uterine anomalies. Previous stillbirth or neonatal death. Autoimmune conditions. Placental risk factors. | Investigations: - Transvaginal cervical length ultrasound scans. Interventions: - Vaginal progesterone. - Cervical cerclage. - Mental health support. - ‘Medical interventions’ not further specified. | Timing of planned visit is not reported, however the median gestational age at first visit was 13+ 6 weeks. Frequency of review and timing of last visit is not reported. |
13. Stricker 2016 Retrospective cohort study. October 2008 – December 2014. Marburg, Germany. | 106 women; ethnicity not reported. Risk factors for spontaneous preterm birth: previous preterm birth < 37 weeks 33%, previous surgical conisation 19%, previous cervical cerclage for a short cervix 12%, short cervix <3rd centile in current pregnancy 48%. Spontaneous preterm birth rate < 37 weeks 44%, < 34 weeks 28%. | Previous preterm birth or mid-trimester loss at 16–37 weeks. Previous surgical conisation. Previous cerclage for a short cervix. Short cervical length < 3rd centile on transvaginal scan in current pregnancy. | Investigations: - Transvaginal cervical length ultrasound scans. Interventions: For singleton pregnancies with a short cervix <3rd centile: - Cervical pessary. - Vaginal progesterone. - Cervical cerclage. | Gestation of planned first visit and frequency of review not reported. Women are discharged at 32 weeks. |
14. Danti 2014 Randomised controlled trial. May 2000 – May 2003. Hospital of the University of Brescia and University of Turin, Italy. | 87 women; Caucasian 95%, others not reported. Risk factors for spontaneous preterm birth: short cervix ≤25 mm at 24–32 weeks 100%, previous preterm delivery or PPROM 14%, previous mid-trimester miscarriages 3%, uterine anomalies (bifid uterus, uterine septum, myoma) 3%, previous cervical surgery 1%. Spontaneous preterm birth rate < 37 weeks 15%. | Previous preterm labour and/or PPROM. Previous mid-trimester miscarriage. Previous cervical insufficiency. Previous cervical surgery. Uterine fibromyoma. Uterine malformations Clinical suspicion of cervical shortening. | Investigations: - Transvaginal cervical length ultrasound scans. - Vaginal culture for trichomonas, aerobic and/or anaerobic bacteria, chlamydia. - Rectal samples for beta haemolytic streptococcus. Interventions: - Cervical cerclage. - Vaginal progesterone. - Targeted antibiotic therapy for positive cultures. Tocolysis (nifedipine) as the study intervention (compared to placebo). | The first visit is planned for 14 weeks. Frequency of planned review not reported. Women are discharged at 34 weeks. |