1 McRae DN, et al. BMJ Open 2018;8:e022220. doi:10.1136/bmjopen-2018-022220 Open access Reduced prevalence of small-for- gestational-age and preterm birth for women of low socioeconomic position: a population-based cohort study comparing antenatal midwifery and physician models of care Daphne N McRae, 1 Patricia A Janssen, 1 Saraswathi Vedam, 2 Maureen Mayhew, 1 Deborah Mpofu, 3,4 Ulrich Teucher, 5 Nazeem Muhajarine 4 To cite: McRae DN, Janssen PA, Vedam S, et al. Reduced prevalence of small-for- gestational-age and preterm birth for women of low socioeconomic position: a population-based cohort study comparing antenatal midwifery and physician models of care. BMJ Open 2018;8:e022220. doi:10.1136/ bmjopen-2018-022220 ► Prepublication history and additional material for this paper are available online. To view these fles, please visit the journal online (http://dx.doi. org/10.1136/bmjopen-2018- 022220). Received 9 February 2018 Revised 5 June 2018 Accepted 29 August 2018 For numbered affliations see end of article. Correspondence to Dr Daphne N McRae; daphne.mcrae@ubc.ca Research © Author(s) (or their employer(s)) 2018. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ. ABSTRACT Objective Our aim was to investigate if antenatal midwifery care was associated with lower odds of small- for-gestational-age (SGA) birth, preterm birth (PTB) or low birth weight (LBW) compared with general practitioner (GP) or obstetrician (OB) models of care for women of low socioeconomic position. Setting This population-level, retrospective cohort study used province-wide maternity, medical billing and demographic data from British Columbia, Canada. Participants Our study included 57 872 pregnant women, with low socioeconomic position, who: were residents of British Columbia, Canada, carried a singleton fetus, had low to moderate medical/obstetric risk, delivered between 2005 and 2012 and received medical insurance premium assistance. Primary and secondary outcome measures We report rates, adjusted ORs (aOR), and 95% CIs for the primary outcome, SGA birth (<the 10th percentile), and secondary outcomes, PTB (<37 weeks’ completed gestation) and LBW (<2500 g). Results Our sample included 4705 midwifery patients, 45 114 GP patients and 8053 OB patients. Odds of SGA birth were reduced for patients receiving antenatal midwifery versus GP (aOR 0.71, 95% CI 0.62 to 0.82) or OB care (aOR 0.59, 95% CI 0.50 to 0.69). Odds of PTB were lower for antenatal midwifery versus GP (aOR 0.74, 95% CI 0.63 to 0.86) or OB patients (aOR 0.53, 95% CI 0.45 to 0.62). Odds of LBW were reduced for midwifery versus GP (aOR 0.66, 95% CI 0.53 to 0.82) or OB patients (aOR 0.43, 95% CI 0.34 to 0.54). Conclusion Antenatal midwifery care in British Columbia, Canada, was associated with lower odds of SGA birth, PTB and LBW, for women of low socioeconomic position, compared with physician models of care. Results support the development of policy to ensure antenatal midwifery care is available and accessible for women of low socioeconomic position. Future research is needed to determine the underlying mechanisms linking midwifery care to better birth outcomes for women of low socioeconomic position. INTRODUCTION  As established in the literature, women of low socioeconomic position (SEP) are more susceptible to poor infant birth outcomes compared with women of higher SEP. 1 In response to this inequity, researchers have sought to determine if antenatal midwifery care could minimise the risk of adverse newborn outcomes for women of low SEP. In a 2016 scoping review of randomised trials and observational studies from high-re- source countries (1990–2015), comparing antenatal midwifery versus physician-led care for women of low SEP, 2 results indicated lower risk of preterm birth (PTB), 3 low birth weight (LBW) 4 and/or very low birth weight (VLBW) 4 5 for midwives’ patients in some studies (or subpopulations within studies), Strengths and limitations of this study ► This large, population-level cohort study (n=57 872) represented the majority of pregnant women with low socioeconomic position in British Columbia, Canada (2005–2012). ► The rigorous modelling approach controlled for correlation in outcomes at a family and community level. ► Findings are generalisable to other high-resource settings which offer similar, publicly funded mid- wifery services. ► The study was limited by self-selection of care pro- vider which could have introduced differences be- tween cohorts in social/health risks undocumented in the maternity record. ► Results included a post hoc analysis controlling for antepartum morbidity to assess the magnitude of self-selection bias. on June 9, 2020 by guest. Protected by copyright. http://bmjopen.bmj.com/ BMJ Open: first published as 10.1136/bmjopen-2018-022220 on 3 October 2018. Downloaded from