Background
Objectives
Methods
Types of study
Types of participant
Types of intervention
Types of outcome measure
Search and screening strategy
Methodological quality assessments
Data collection and analysis
Results
Results of database searching
Description of included studies
Description of randomised studies
Study ID, design, country | Participants | Intervention | Outcomes | Results |
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Randomised controlled trials (RCTs) | ||||
1. Iams and Johnson [21], single centre, study duration 1983 to 1986 (abstract only), USA | 370 high-risk women based on Creasy scoring system were selected from 2829 women attending antenatal clinic. One hundred eighty-two women received routine antenatal care plus preterm birth prevention clinic the intervention and 188 women received routine antenatal care. | Preterm birth prevention clinic group received education about symptoms and signs of labour and the cervix examined at weekly visits between 20 and 36 weeks’ gestation Control group received standard antenatal care. | 1.Preterm labour (intervention vs control): 50/182 vs 40/188, P = 0.17 2. Preterm birth < 37 weeks (intervention vs control): 24/50 (48%) vs 35/40 (87.5%), P = 0.001 | No significant difference between the two groups with regards to the incidence of preterm labour. Significant difference between the two groups with regard to preterm birth among women who developed preterm labour. |
2. Main et al. [22], single centre, study duration: 3.5 years, USA | 367 black women at gestational age > 18 weeks were at high risk of preterm labour based on Creasy et al. [32] scoring criteria. Inclusion criteria: Black women with gestational age < 18 weeks were referred to the nurse specialist in the Preterm Labour Detection Clinic. Intervention group: N = 178, maternal age (yr) 23.9 ± 5.5, gravidity 3.7 ± 1.9, parity 1.4 ± 1.2, abortions ≤ 14 weeks 1.0 ± 1.0, abortion > 14 weeks 0.3 ± 0.7, women with previous preterm delivery 38%, gestational age at first visit (wk) 12.5 ± 3.7. Control group: N = 198, maternal age (yr) 24.1 ± 5.1, gravidity 3.8 ± 1.9, parity 1.6 ± 1.5, abortions ≤ 14 weeks 0.9 ± 1.1, abortion > 14 weeks 0.3 ± 0.7, women with previous preterm delivery 43%, gestational age at first visit (wk) 12.0 ± 3.3. | Attending a preterm labour detection clinic on a weekly or biweekly basis from 22 weeks’ gestation and cervical assessment by 1 of 3 physicians at each visit. Also education provided by a nurse specialist regarding subtle signs of labour. High risk control: received usual prenatal care. | 1.Preterm deliveries (intervention vs control): <28 weeks: 3% vs 3.9%, p = 0.42, 32 < 34 weeks: 6.6% vs 6.2%, p = 0.51, <36 weeks: 16.7% vs 13.4%, p = 0.46, <37 weeks: 23.2% vs 20.7%, p = 0.32, 2. Neonatal outcomes: 5-min Apgar <5 4.5% vs 6.1%, p = 0.32. Caesarean birth: 23.7% vs 21.2%, p = 0.64. NICU admission: 10.4% vs 16.4%, p = 0.32. Length of stay > 5 days: 21.4% vs 18.7%, p = 0.33. Stillborn: 4.8% vs 2.9%, p = 0.53. Neonatal deaths: 0% vs 0.7%, p = 0.48. 3. Cost/Hospital charges: Maternal charges: $5687 ± 4222 vs $5846 ± 4872, p = 0.97 Neonatal charges: $4958 ± 26,491 vs $4287 ± 24,247, p = 0.83. 4. Maternal hospital admission: Mean no. maternal hospital admissions: 1.7 ± 1.1 vs 1.3 ± 0.7, p = 0.0001, Women with one or more antepartum admissions: 44% vs 26%, p = 0.001. | No significant differences between the two high risk groups with respect to mean gestational age at delivery, birth weight or percentage delivering before term. |
3. Mueller-Heubach [23], study duration 3 years between September 1984 and August 1987, USA | 5457 women were scored for risk of preterm birth using the Creasy scoring system 1980, and 18.1% were classified as high risk these were randomised into two groups. Exclusion criteria: Patients registered after 28 weeks’ gestation. | The intervention group received weekly cervical examinations and teaching about signs and symptoms of preterm labour. Health care professionals received similar instructions. Historical control was used due to high contamination. The control group received the usual antenatal care. | Preterm birth rate (intervention vs control): 22.1% vs 20.8%, p > 0.05 Preterm birth in year one: 13.7%, in year two 9.3%, p < 0.001 and in year three 8.9%. Neonatal death (second and third year): 5/1755 vs 11/1203 the incidence: 2.8/1000 vs 9.1/1000. | There was no difference in preterm birth between the intervention and the control. There was a significant reduction in preterm birth rate in year 3 compared to year 1. There was a significant decrease in the neonatal death in the second and third year of the intervention compared with the control. |
4. Goldenberg et al. [24], five centres, study duration 1982–1986 (singleton and, multiple pregnancies), USA | 1000 high risk women were randomized to intervention or control. Seventy percent were black and 35% were younger than 20 years and 4% were 35 years or older. 3.5% in the intervention had multiple pregnancy and 4.2% in the control. Inclusion criteria: women with an estimated date of delivery between 1 November, 1982 and April 1, 1986, at < 30 weeks gestational age, women were classified as high risk based on a score of 10 or more on the based on Creasy et al. [32] criteria. | The intervention group attended the clinic weekly and pelvic examination and education about preterm signs and symptoms. Primary care was provided by a specially trained nurse who saw the same woman. Women in the control group received usual prenatal care. | 1. Pregnancy outcomes (intervention vs control): Spontaneous preterm labour: 26.9% vs 16.3% Spontaneous premature rupture of membranes (PROM) 6.3% vs 4.4% Preterm delivery incidence: 6.3% vs 2.5% Spontaneous delivery < 28 weeks: 2.7% vs 1.3%, p > 0.05 Spontaneous delivery <36 weeks: 11.8% vs 10.5%, p > 0.05 Spontaneous delivery < 37 weeks: 15.9% vs 14.2%, p > 0.05 Birth weight 1500–2499 g: 37.7 ± 3.8 vs 38.1 ± 3.1, p > 0.05 Mean birth weight: 2892 ± 771 vs 2935 ± 679, p > 0.05 2. Neonatal outcomes: Respiratory distress syndrome: 5.9% vs 3.8%, p > 0.05 Hyperbilirubinemia: 7.9% vs 9.4%, p > 0.05 Necrotizing enterocolitis: 0.6% vs 1.8%, p > 0.05 Patent ductus arteriosus: 2.4% vs 1.6%, p > 0.05 Interventricular haemorrhage: 1.8% vs0.4%, p < 0.05 Congenital anomaly: 6.75 vs 7.8%, p > 0.05 Sepsis: 0.8% vs 0.8%, p > 0.5 Hypoglycaemia:2.3% vs 4%, p > 0.5 Need for resuscitation: 8.2% vs 8%, p > 0.05 NECU: 27.4% vs 26.6%, p > 0.05 Time on ventilator: <12 h:93.5 vs 97.4, P < 0.05; >12 h: 6.5% vs 2.4%, p < 0.05 Babies days in hospital: ≤7: 89% vs 91.8%, p > 0.5; >7 11% vs 8,2%, p > 0.05 | Preterm labour diagnosis and spontaneous preterm PROM diagnosis were higher in the intervention group, but the difference was not significant. No significant difference between the groups on most the neonatal outcomes. |
5. Hobel et al. [25], multicentre study, 5 clinics in the intervention and three in the control, recruitment lasted from 1983 to 1986, USA | 1774 high-risk women in the intervention clinics and 880 in the control clinics. Women were predominantly Hispanics. Inclusion criteria: Had a gestational age of <31 week, no disabling condition, and were English or Spanish speaking. Exclusion criteria: major congenital anomaly, multiple births, pregnancies with missing charts of cost information. | Intervention group received preterm birth prevention education plus increased antenatal visits to the clinic and selected prophylactic interventions. Visits were scheduled at 2 weeks intervals, 3 educational classes about preterm birth prevention, nutritional and psychosocial screening and offered treatment when it was needed. The control clinics offered visits at 4 weeks intervals up to 30 weeks ‘gestation, then every 2 weeks from 30 to 35 weeks’ gestation, then weekly until delivery. | 1. Number of clinic visits(intervention vs control): 6.4 ± 3.4 vs.9 ± 2.5, p < 0.05 2. Preterm rate: 7.4% vs 9.1%, p = 0.063 3. Birth weight <2500gm: 5.8% vs 6.4%, p = 0.15 4. Gestatioanl age: 39.8 ± 2.3 vs 39.9 ± 2.5, p = 0.38 4. Inpatient costs per New born: <37 weeks: (n = 95, 17,206 ± 3995 vs n = 55, 31,129 ± 8572) ≥37 weeks: (n = 70, 2025 ± 273 vs n = 70, 2763 ± 628) 5. Average new born inpatient cost:$3146 vs $5342 | No significant difference between the two groups with regards to the incidence of preterm birth, low birth weight and gestational age. High risk prevention clinics had an average cost savings of $2196 for new born care (p = 0.2). |
Cohort studies | ||||
1. Herron et al. [26], prospective-cohort, single centre, between July 1, 1978 and June 30, 1979, USA. | Patients were screened based on the Creasy criteria 1980 and divided into two groups: 176 (15.2%) women assigned to the high risk group and 974 (84.8%) to the low-risk group. | For the high risk group: The intervention involved: the first visit to the clinic included education regarding the signs and symptoms of preterm labour and training the participants in self-detection of painless contractions. Weekly antenatal visit to the clinic, if the symptoms of painless labour occurs then patients were monitored for 1–2 h. Reporting to the clinic immediately if one of the preterm signs and symptoms occurred. AT the weekly visit the pelvic examination was performed by the same physician. If preterm labour occurred then patients admitted to hospital and tocolytic therapy was given. Staff training and education to prompt response to patients’ complaints, of any preterm signs and symptoms, early admission to patients having a mild increase uterine activity, aggressive therapeutic approach in patients with documented preterm labour, awareness of long term side effects of the tocolysis. | 1.Preterm labour(comparing high risk group to low risk): 30/176 (17.5%) vs 24/974 (2.5%), p < 0.05, 2. Preterm delivery (comparing high risk group to low risk group): 7/176 (4%) vs 9/974 (0.9%), p > 0.05. 3. Men gestational age at delivery (comparing high to low group): 33.7 ± 2.6 vs 33.3 ± 3.6 weeks 4. Preterm birth ≤ 36 weeks at year 1 after introducing the clinic: 2.4% compared with 6.75% before the clinic. | A significant decrease in preterm birth with the clinic. |
2. Manuck et al. [27], Retrospective cohort, multi-centre study from 17 hospitals, participants’ enrolment from 2008 to 2010, USA. | Inclusion criteria: Single pregnancy, previous PTB <35 weeks. Exclusion criteria: Women who delivered preterm babies <37 weeks due to medical or foetal complications, eg, preeclampsia, foetal growth restriction. Women excluded from the study analysis if they had a history of incompetent cervix (painless cervical dilation <24 week’s gestation). Total number of patients: 223 PTB clinic group: n = 70 Maternal age 28.5 years, white 83.1%, smoking 3.4%, married 86.4%, primary obstetrics provider is perintalogist 18.6%; number of PTB <37 weeks 1.7 (mean) Usual care group: n = 153 Maternal age 28.8% years, white 88.8%, smoking 9.8%, married 83%, primary obstetrics provider is perintalogist 11.8%; number of PTB <37 weeks 1.6 (mean) | The recurrent PTB prevention clinic includes three visits (10–18 weeks, 19–24 weeks, and 28–32 weeks): Detailed obstetric history and personal recurrence risk assessment: at visit 1 (10–18 weeks) Screen for BV and treat if positive with oral metronidazole at all three visits. Urinalysis : at all three visits Urine culture: at all visits (symptoms positive or urinalysis is positive). Transvaginal cervical length: at all visits. Cervical length <2.5 cm is abnormal. Offer 17 alpha hyroxyprogesterone caproate: at visit one for all patients, patients who declined were offered the treatment again at week 24 if cervical shortening is noted. Usual care group: Managed by their primary obstetrician without being referred to the clinic. | Primary outcome (PTB clinic vs usual care): 1. PTB < 37 weeks,%: 48.6% vs 63.4%, p=0.02 2. PTB < 37 weeks,%: 5.7% vs 13.7%, p=0.08 3. Delivery GA, mean wk: 36.1 vs 34.9, p = 0.02 Secondary outcomes: 1. Neonatal morbidity, %: 5.7 vs 16.3, p = 0.03 2. NICU admission, %: 44.3 vs 41.2, p = 0.66 3. Mean inpatient maternal cost: $6929 vs $7706, p = 0.48 4. Mean inpatient neonatal cost: $11,818 vs $15,662, p = 0.05 | 28% reduction in the risk of recurrent PTB <37 weeks and >1 week of pregnancy prolongation and reduced the rate of major neonatal morbidity with the intervention. |
3. Karkhanis et al. [28], retrospective-cohort from November 2007 to January 2009, Birmingham-UK (abstract) | 180 high risk women, mean age 29.85 years (18–41), mean BMI = 27.52 kg/m2, N = 158 with previous preterm labour or mid trimester loss. | All patients in the preterm prevention clinic underwent serial transvaginal scan monitoring and infection screening between 16 and 28 weeks. 40 women underwent cervical cerclage and progesterone 35 women received progesterone only | 1. Term delivery > 37 weeks: n = 123/180 2. Term delivery >37 weeks after one preterm delivery (PTD): 79% 3. Term delivery > 37 weeks after 2 PTD:71% 4. Term delivery >37 weeks after 3 PTD:60% 5. NICU admission: n = 36 babies 6. Infant mortality: n = 7 | The preterm prevention clinic reduced prematurity rate. |
4. Burul et al. [29], retrospective-cohort, clinic cases from January 2005 to December 2008, London-UK (abstract). | 210 cerclage cases: 85 cases before the establish of the clinic and 125 afterwards | Cervical cerclage | 1. Elective cervical cerclage 44% before the clinic vs 88% after establishing the clinic 2. GA at delivery 28 + 2/40 before the PTBC compared with 35 + 2/40 with the clinic care | |
5. Cohen et al. [30], audit of two London preterm surveillance clinics between January 2013 and May 2014, UK (abstract). | 509 pregnancies reviewed; mean age 33.6 years (18–49 years), BMI 24.4 (range 17–48), 59% White and 15% Afro-Caribbean. Reasons for referral to the clinics: Previous cervical treatment (50%) Previous preterm birth before 34 weeks 926%), mid trimester miscarriage (MTL) (17%) Uterine anomalies (2%) Multiple pregnancy (3%) | Clinic interventions: Cervical shortening found in 44% Progesterone supplementations 25% Cervical cerclage 27% | Preterm delivery: <28 weeks 0.7% delivered <34 weeks 4% delivered <37 weeks 11% derived | Early referral to the clinics for better monitoring. |
Description of cohort studies
Description of qualitative studies
Study ID, country | O’Brien et al. [31], UK |
Study Aims | High risk pregnant women’s views on attending a specialised antenatal clinic. |
Ethics | Study was reviewed by the hospital’s Research & development committee and gained ethical approval from local research ethics committee. |
Participants | Women who had a previous preterm birth, experience antenatal care for the current pregnancy was provided in preterm clinic and English speaking. Women were excluded if they had a known foetal malformation. |
Recruitment | Specialist preterm clinic. |
Sampling method | Women were identified for inclusion in the study through obstetrician referral. |
Participants characteristics | 37 women were interested in participating in the study and 14 were interviewed. Age range 23–44 years; 13 were white and one Black Caribbean. Gestational age an interview range (14–32 weeks). |
Data quality rating | Two independent researchers analysed the data. |
Data collection | Three focus groups and face to face interviews. |
Data analysis | Interpretative approach (thematic coding method) was used. |
Data extracts | Data transcribed anonymously, coding and categories and themes were developed by two researchers. |
Themes | 1. Balancing the risks: Women were aware of their risk, but viewed positively due to the extra care (“I would prefer to know and I would see it as a positive thing because you would expect that they would monitor you closely and if necessary give you medication or obviously try and lower the risk somehow to have a successful pregnancy”). 2. Threat of preterm labour: All women felt paranoid about potential signs or symptoms of PTB “Just get through this bit. 3) Personal coping buy developing strategies to survive the pregnancy however, women tried not to focus on their pregnancy avoiding bonding with the baby and were reluctant to look too far to the future. a) Recognizing that something does not feel right: Ignoring the warning signs of PTL with previous pregnancies, however, the PTB was realised they were feeling guilty and not ignoring their intuition again: (“When I look back, leading up to actually having her there were some little signs. And I was very much ignoring them because I was thinking I was being paranoid and silly… the promise that we made to ourselves and particularly to myself was that I am just not going to take any risks….. I don’t care if anyone thinks I ‘m paranoid, you know, or nuts, whatever, as long as I eventually have a healthy baby”). Some women struggled with the health professional to have their concerns taken seriously. Some felt worse after interactions with health professionals in the clinic. c) Need regular reassurance from health professionals were not always sensitive to women’s worries about the risk of PTL, felt better with the routine reassurance of the clinic screening and scanning. |
Quality assessment of quantitative research
Study/year | Selection bias | Allocation to intervention | Performance bias | Baseline differences in characteristics | Baseline differences in outcomes | Contamination | Attrition bias | Selective reporting | Other bias |
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Randomized controlled trials (RCTs) | |||||||||
1. Hobel et al. [25] | Low: Cluster randomization with a restricted block | Low: cluster randomization. | Low: women were not aware of their intervention status nor the clinics teams | Low: participants were comparable with respect to age, marital status, gravidity, parity and preterm birth rate | Low: no difference between the groups with regards to high risk preterm problems at baseline | Low: intervention was provided on a clinic-basis rather than patients | Unclear: the number of women who left the study was not reported | Low | low |
2. Main et al. [22] | High: a random numbers table was used for the first 479 participants then the second sample of464 women was divided into groups by birthday date | High: women’s’ date of birth was used to allocate women to intervention or control | Low: In the control group neither the doctors nor the women were made aware they were at high risk of preterm birth. | Low: no differences between groups with respect to maternal age, gravidity, parity, previous preterm deliveries, and gestational age at first visit | High: More women with previous preterm birth were assigned to the intervention. | High: 8 women from the control group transferred to the clinic | High: insufficient reporting on the rate of attrition. | Unclear | Low |
3. Iams and Johnson [21] | Unclear | Unclear | Unclear | Unclear | Unclear | Unclear | Unclear | Unclear | Unclear |
4. Goldenberg et al. [24] | Low: randomization by a randomization officer | Unclear: allocation to intervention or control method was not reported | Low: nobody was aware of the intervention status | Low: No significant difference between high-risk group and high-risk control with regard to number of birth, race, age and parity | Low: no differences of previous preterm birth and multiple pregnancies between the two groups | low | Unclear: the number of missing women was not reported | Low | Low |
5. Mueller-Heubach [23] | Low: participants were selected to intervention and controlled randomly | Unclear: method of allocation to intervention or control was not reported | High: nurses were aware of the intervention status of the participants | Low | Low | High: a historical control was used in the analysis | Unclear | low | low |
Cohort studies | |||||||||
1. Herron et al. [26] | High | High | High | Low | Unclear | Low | Low | Low | Low |
2. Manuck et al. [27] | High | High | High | Low | Low | Low | Low | Low | Low |
3. Karkhanis et al. [28] (abstract) | High | High | High | Unclear | Unclear | Low | Unclear | Unclear | Unclear |
4. Burul [29] (abstract) | High | High | High | unclear | Unclear | Low | Unclear | Unclear | Unclear |
5. Cohen et al. [30] (abstract) | High | High | High | Unclear | Unclear | Low | Unclear | Unclear | Unclear |
Quality of evidence of qualitative study
Study ID | O’Brien et al. [31] |
Study objective | Yes, understanding the women’s experiences of attending and being referred to the specialist antenatal clinic. |
Appropriate method | Yes, qualitative methodology is appropriate to seek women’s experience of the clinic. |
Study design | Yes, through focus groups and in depth face to face interviews. |
Recruitment strategy | Yes, women were enrolled from a specialist clinic which is a major referral centre in the North West England. |
Data collection | Yes, data collected through focus groups and face to face interview. All were recorded and transcribed and data saturation was discussed. |
Researcher-participant relationship | Unclear, no information was given. |
Ethical approval | Yes, study reviewed by Hospital’s Research and development Committee. |
Data analysis | Yes, data was analysed by two independent researchers using the constant comparative method. |
Study findings | Yes, three themes were explicitly defined and the credibility of the findings was also clearly discussed. |
Study values | Yes, researchers identify a new area for further research. |
Effects of the interventions from quantitative research
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Preterm birth: (birth < 37 weeks’ gestation):Results from all RCTs [21‐25] showed no significant difference between the intervention and the control groups in preterm delivery (7.4% vs 9.1%, p = 0.063; 23.2% vs 20.7%, p = 0.32; 22.1% vs 20.8%, p > 0.05; 15.9% vs 14.2%, P > 0.05; and 22.1% vs 20.8%, P > 0.05?) respectively. In contrast, results from cohort studies showed a reduction of preterm birth incidence after the clinic was introduced. A 28% reduction in the risk of preterm birth in comparison to data from women receiving usual care was reported in Herron et al. [26]. In Karkhanis et al. [28], the prematurity rate was reduced and the term delivery > 37 weeks’ figures were reported for women with one (74%), two (42%) and three (41%) previous preterm deliveries.
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Very preterm birth (birth before 34 weeks’ gestation) and extremely preterm birth (birth <28 weeks’ gestation):
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Gestational age at birth:Results from one study [25] showed no significant differences between women attending the specialist clinic mean gestation 39.8 (2.3) and women receiving usual care 39.9 (2.3) weeks, p = 0.32. The median gestational age at delivery increased from 28 + 2/40 to 35 + 2/40, P = 0.6, in the cohort study reported by Burul et al. [29].
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Stillbirth:One RCT [22], reported no significant difference between the women in the two groups, with seven deaths reported in the intervention group compared with six in the control.