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Obstetrics and gynaecology
Research
Risk of perinatal mortality in the first year of midwifery practice in New Zealand: analysis of a retrospective national cohort
  1. Lynn C Sadler1,2,
  2. Judith McAra-Couper3,
  3. Deborah Pittam4,5,
  4. Michelle R Wise6,
  5. John M D Thompson7
  1. 1 Women’s Health, Auckland District Health Board, Auckland, New Zealand
  2. 2 Department of Epidemiology and Biostatistics, Faculty of Medical and Health Science, University of Auckland, Auckland, New Zealand
  3. 3 Midwifery Department, Auckland University of Technology, Auckland, New Zealand
  4. 4 Maternity Services, Northland District Health Board, Whangarei, New Zealand
  5. 5 New Zealand College of Midwives, Christchurch, New Zealand
  6. 6 Department of Obstetrics and Gynaecology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
  7. 7 Departments of Paediatrics, Child and Youth Health, and Obstetrics and Gynaecology, Faculty of Medical and Health Science, University of Auckland, Auckland, New Zealand
  1. Correspondence to Dr Lynn C Sadler; lynns{at}adhb.govt.nz

Abstract

Objectives To determine whether there was an increased risk of perinatal mortality among mothers booked for care with community lead maternity carer (LMC) midwives in their first compared with later years of practice.

Design Retrospective cohort study using linked national maternity, mortality and workforce data; adjusted analysis using logistic regression.

Setting New Zealand.

Participants Women under community LMC midwifery care birthing 2008–2014.

Main outcome measures Perinatal mortality (stillbirths and neonatal deaths of babies born from 20 weeks’ gestation to the 27th day of postnatal life), excluding terminations and deaths associated with congenital abnormalities.

Results There were 2045 deaths among 344 910 births booked with midwives.

First year of practice midwives cared for women with higher risk of perinatal mortality, including Māori, Pacific, Indian, <20-year-old mothers, nullipara, smokers, women living in socioeconomic deprivation and with high body mass index, than midwives beyond first year of practice.

There was a significant reduction in unadjusted odds of perinatal mortality among women under the care of midwives beyond the first year compared with those within the first year (OR 0.79, 95% CI 0.67 to 0.93) but no significant reduction in risk remained after adjusting for known risk factors, (OR 0.89, 95% CI 0.74 to 1.07).

There was a significant increase in the adjusted odds of perinatal mortality among midwives booking a caseload of 15 or fewer mothers per year (1.34, 1.01 to 1.78) and 16 to 30 (1.25, 1.04 to 1.50) compared with midwives booking 51 to 80.

Conclusions Findings suggest that the first year of midwifery practice is not associated with an increased risk of perinatal mortality but there is evidence that early career midwives are caring for higher-risk women. These findings suggest inequity of access for higher-risk women to experienced midwives and highlight an opportunity to improve support for vulnerable women and new midwives.

  • midwifery
  • perinatal mortality
  • practice experience

This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/

https://doi.org/10.1136/bmjopen-2017-019026

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    Footnotes

    • Contributors LCS and JMDT conceived the protocol for the study and performed the analysis. The first author wrote the first draft of the paper. JMA-C, DP and MRW provided advice on the protocol, the analysis and interpretation of the findings. All authors were involved in editing the paper. LCS is the guarantor for the study. The first and last authors had access to the data throughout the study while the other authors did not. The lead author affirms that the manuscript is an honest, accurate and transparent account of the study being reported; that no important aspects of the study have been omitted and that any discrepancies from the study as planned have been explained. The authors requested that the study findings be submitted for publication and were responsible for preparation of the manuscript.

    • Funding The first and last authors of this study were supported by the New Zealand Ministry of Health and the Accident Compensation Commission (ACC) of New Zealand.

    • Disclaimer The funder (NZ Ministry of Health) requested a replication of the original study, but did not contribute to the study design, analytical plan, analysis or interpretation of the data. The authors approached the funders when it was clear that the initial study analysis could not be completed and proposed a change of the timeframe to 2008–2014. The sponsors/funders have not reviewed the paper prior to submission. All decisions were independent of the funders.

    • Competing interests JMcA-C is paid as the Chair of the Midwifery Council of NZ and DP is paid as the President of the NZ College of Midwives

    • Patient consent Not required.

    • Ethics approval New Zealand Northern A Health and Disability Ethics Committee (16/NTA/1).

    • Provenance and peer review Not commissioned; externally peer reviewed.

    • Data sharing statement The data for this study are not available for sharing; however, a similar dataset could be obtained from the New Zealand Ministry of Health, the New Zealand Midwifery Council and the PMMRC upon provision of usual ethical applications and consents.