Abnormally invasive placenta and birth outcomes in NSW

Clinical and Population Perinatal Health Research has an ongoing program of research investigating aspects of maternity and perinatal health care for women at high risk of adverse outcomes. One recent area of research has focussed on women with an abnormally invasive placenta (sometimes referred to as morbidly adherent placenta, including placenta accreta, increta and percreta). Two papers were published in 2017 and 2018 investigating maternal and neonatal outcomes following abnormally invasive placenta, and antecedents to development of this pregnancy complication.1,2 This work showed that:
  • ​The incidence of a of abnormally invasive placenta is increasing.
  • Abnormally invasive placenta is with associated increased risks of severe adverse outcomes for mothers and babies including:
    • a five-fold increase in post-partum haemorrhage
    • a five-fold increased risk of stillbirth, and 
    • an eight-fold increased risk of neonatal death.
  • ​Over one-third of women with an abnormally invasive placenta were nulliparous, even though suspicions for abnormally invasive placenta are usually reserved for multiparous women. 
  • In nulliparous women, prior invasive gynaecological procedures increased the risk of developing abnormally invasive placenta. 
  • Gynaecological procedures that increased the risk of abnormally invasive placenta included gynaecological laparoscopy with instrumentation of the uterus, hysteroscopy, and curettage, including suction curettage and surgical termination. 
  • The risk of abnormally invasive placenta increased with increasing numbers of prior invasive gynaecological procedures.
  • After accounting for other pregnancy characteristics, women with one prior procedure had a 50% increased risk of abnormally invasive placenta, while women with three or more previous procedures had five times higher risk than women with no history of procedures.
  • IVF may be associated with abnormally invasive placenta; IVF rates were twice as high among women with an abnormally invasive placenta compared to those without. 
Activities to support translation of this research into practice included presentation of findings at the annual Women’s and Newborn Academic Day at Royal North Shore Hospital, and an invited presentation and discussion at the Australian and New Zealand Society of Reproductive Endocrinology and Infertility 2018 Annual Conference. The IVF community in particular was interested in the findings of nulliparous women having IVF and the relationship with abnormally invasive placenta in subsequent pregnancies; many IVF procedures now include an ‘endometrial scratch’ gynaecological procedure in the hope to improve livebirth rates, but this may be related to increasing abnormally invasive placenta.

This work is of relevance to clinicians, women and their families, maternity care providers as well as policy makers. Both abnormally invasive placenta papers were cited by the Society for Maternal-Fetal Medicine and the American College of Obstetricians and Gynecologists clinical guideline on management of placenta accreta in December 2018. An article3 in Obstetrics and Gynecology cites our antecedents paper2 as one of the best morbidly adherent placenta articles of the past year.

This work was completed by a trainee biostatistician funded through the NSW Health Prevention Research Support Program and supervised by Clinical and Population Perinatal Health Research staff. Using de-identified Perinatal Data Collection and Admitted Patient Data Collection data that were linked by the Centre for Health Record Linkage, multilevel modelling was undertaken to investigate the associations between: abnormally invasive placenta and adverse maternal and neonatal outcomes; and prior invasive gynaecological procedures and the risk of abnormally invasive placenta.

References

  1. Baldwin HJ, Patterson JA, Nippita TA, Torvaldsen S, Ibiebele I, Simpson JM, Ford JB. Maternal and neonatal outcomes following abnormally invasive placenta: a population‐based record linkage study. Acta Obstet Gynecol Scand 2017; 96(11): 1373-81. DOI: 10.1111/aogs.13201 
  2. Baldwin HJ, Patterson JA, Nippita TA, Torvaldsen S, Ibiebele I, Simpson JM, Ford JB. Antecedents of abnormally invasive placenta in primiparous women: risk associated with gynecologic procedures. Obstet Gynecol 2018; 131(2): 227-33. DOI: 10.1097/AOG.0000000000002434
  3. Dashe JS. What is new in morbidly adherent placenta? Best articles from the past year. Obstet Gynecol 2018; 131(6): 1153-5.
Current as at: Monday 31 May 2021
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