Evaluation of the introduction of a midwifery continuity of care model for women at increased risk of preterm birth in South London, United Kingdom

Student thesis: Doctoral ThesisDoctor of Philosophy


Preterm birth (birth before 37 completed weeks of gestation) remains a public health priority worldwide and in the UK. It has a complex and multifactorial nature that limits the understanding of causal pathways and the development and implementation of effective interventions and public health prevention strategies designed to address prematurity. So far, midwifery continuity of care models are the only health system intervention shown to reduce preterm birth, increase perinatal survival and improve experiences of care, but no evidence exists for women with identified risk factors for preterm birth. The aim of this thesis is to evaluate the feasibility and implementation of a model of midwifery continuity of care linked with a specialist obstetric clinic for women considered to be at risk of preterm birth (the [Pilot study Of midwifery Practice in Preterm birth Including women’s Experiences POPPIE] model).

A hybrid type 2, randomised, controlled, unblinded, parallel-group pilot trial with a nested mixed methods evaluation was undertaken at an inner-city maternity service in South London (United Kingdom). The feasibility outcomes included eligibility, recruitment and attrition rates, and fidelity of the model. The primary clinical composite outcome was at least one of timely and appropiate interventions provided for the prevention and/or management of potential preterm labour and/or birth. The secondary clinical outcomes included maternal and neonatal outcomes. Women’s experiences were measured and compared using a postnatal survey, and explored in depth using qualitative interviews. The implementation of the POPPIE model and potential mechanisms of action were measured and integrated with interviews of women and key stakeholders and analysis of organisational documents, and measures of contextual factors.

Between 9 May 2017 and 30 September 2018, 334 women were recruited (out of 553 screened and 430 eligible); and 169 were allocated to the POPPIE group and 165 to the standard group. Loss to follow up was less than 6.5%. Nearly a thrid of women were from Black, Asian and ethnic minority groups, more than two thirds were in employment and lived in areas of social deprivation, and more than a quarter had at least one pre-existing medical condition and multiple risk factors for preterm birth. More than 75% of antenatal and postnatal visits were provided by a named/partner midwife, and a midwife from the POPPIE team was present at 80% of births. The incidence of the primary composite outcome was similar between groups (POPPIE group 83.3% vs standard group 84.7%); risk ratio 0.98 (95% CI 0.90 to 1.08); p=0.742, after adjustments for key measures associated with preterm birth which included ethnicity, parity, education, index of multiple deprivation, and obstetric risk. Compared to women in the standard group, women in the POPPIE group were significantly more likely to have skin to skin after birth, breastfed immediately after birth and at hospital discharge, and report increased perceptions of trust, safety and quality of care. Overall, the POPPIE model was feasible, delivered with high fidelity and acceptable to most women and healthcare providers. There were some initial delays in early adoption related to POPPIE being the first continuity model in the hospital, and involving staff recruitment and a complex reconfiguration of the maternity service. The model was eventually embedded within established services and adapted and sustained after the trial, likely influenced by national NHS policy on continuity pathways.
Some of the potential mechanisms identified included trusting relationships, access to care, safety and advocacy. Overall quality and quantity of the implementation and the trial was considered to be of high quality.

This research demonstrates it is feasible to set up and achieve fidelity of a model of midwifery continuity of care linked with specialist obstetric care for women with risk factors for preterm birth in an inner-city maternity service in South London. There were no differences on most clinical outcomes for the very high risk population group included, but there was a difference on some process outcomes, such as the level of continuity achieved and a range of indicators about trust, safety and quality of care. Measuring implementation alongside the clinical outcomes of the POPPIE model was feasible and beneficial in understanding context and potential mechanisms. It is possible that hypothesised mechanisms of effect based on increased trust and engagement, improved care coordination and earlier referral, may improve outcomes in this and other populations suffering more social determinants of preterm birth such as women with social complexity and who find services hard to access. Larger appropriately powered trials are feasible and needed, including in other settings, to evaluate the impact of continuity of care models on women at increased risk of preterm birth and disadvantaged communities including women with complex social factors and social vulnerability, for which there is little evidence.
Date of Award1 Mar 2021
Original languageEnglish
Awarding Institution
  • King's College London
SupervisorJane Sandall (Supervisor), Andrew Shennan (Supervisor) & Kirstie Coxon (Supervisor)

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