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. 2017 Oct 5;7(10):e017713.
doi: 10.1136/bmjopen-2017-017713.

Incidence, risk factors and perinatal outcomes for placenta accreta in Australia and New Zealand: a case-control study

Cynthia M Farquhar  1 , Zhuoyang Li  2 , Sarah Lensen  1 , Claire McLintock  3 , Wendy Pollock  4 , Michael J Peek  5 , David Ellwood  6 , Marian Knight  7 , Caroline Se Homer  2 , Geraldine Vaughan  2 , Alex Wang  2 , Elizabeth Sullivan  2
Affiliations

Incidence, risk factors and perinatal outcomes for placenta accreta in Australia and New Zealand: a case-control study

Cynthia M Farquhar et al. BMJ Open. .

Abstract

Objective: Estimate the incidence of placenta accreta and describe risk factors, clinical practice and perinatal outcomes.

Design: Case-control study.

Setting: Sites in Australia and New Zealand with at least 50 births per year.

Participants: Cases were women giving birth (≥20 weeks or fetus ≥400 g) who were diagnosed with placenta accreta by antenatal imaging, at operation or by pathology specimens between 2010 and 2012. Controls were two births immediately prior to a case. A total of 295 cases were included and 570 controls.

Methods: Data were collected using the Australasian Maternity Outcomes Surveillance System.

Primary and secondary outcome measures: Incidence, risk factors (eg, prior caesarean section (CS), maternal age) and clinical outcomes of placenta accreta (eg CS, hysterectomy and death).

Results: The incidence of placenta accreta was 44.2/100 000 women giving birth (95% CI 39.4 to 49.5); however, this may overestimated due to the case definition used. In primiparous women, an increased odds of placenta accreta was observed in older women (adjusted OR (AOR) women≥40 vs <30: 19.1, 95% CI 4.6 to 80.3) and current multiple birth (AOR: 6.1, 95% CI 1.1 to 34.1). In multiparous women, independent risk factors were prior CS (AOR ≥2 prior sections vs 0: 13.8, 95% CI 7.4 to 26.1) and current placenta praevia (AOR: 36.3, 95% CI 14.0 to 93.7). There were two maternal deaths (case fatality rate 0.7%).Women with placenta accreta were more likely to have a caesarean section (AOR: 4.6, 95% CI 2.7 to 7.6) to be admitted to the intensive care unit (ICU)/high dependency unit (AOR: 46.1, 95% CI 22.3 to 95.4) and to have a hysterectomy (AOR: 209.0, 95% CI 19.9 to 875.0). Babies born to women with placenta accreta were more likely to be preterm, be admitted to neonatal ICU and require resuscitation.

Keywords: c-section; caesarean; placenta accreta; placentation.

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Conflict of interest statement

Competing interests: All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf and declare: no support from any organisation for the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work.

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