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Women’s health and midwifery
Population data suggest persistently high risk of pregnancy complications in women with chronic kidney disease
  1. Ju-Lee Oei1,2,
  2. Yoga Kandasamy3
  1. 1 Department of Newborn Care, Royal Hospital for Women, Randwick, New South Wales, Australia
  2. 2 School of Women’s and Children’s Health, University of New South Wales, Randwick, New South Wales, Australia
  3. 3 Department of Neonatology, Townsville Hospital and Health Service, Townsville, Queensland, Australia
  1. Correspondence to Professor Ju-Lee Oei, Department of Newborn Care, Royal Hospital for Women, Randwick, NSW 2031, Australia; j.oei{at}unsw.edu.au

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Commentary on: Al Khalaf SY, O'Reilly ÉJ, McCarthy FP, et al. Pregnancy outcomes in women with chronic kidney disease and chronic hypertension: a National cohort study. Am J Obstet Gynecol 2021:S0002-9378(21)00225-8. doi: 10.1016/j.ajog.2021.03.045.

Implications for practice and research

  1. Pregnant women with chronic kidney disease are at risk of pre-eclampsia, preterm birth and caesarean delivery.

  2. They need close surveillance with multidisciplinary expertise to reduce the risk of pregnancy complications which in turn may increase risk of postpartum adverse outcomes if untreated.

Context

Chronic kidney disease (CKD) affects up to 3% of pregnant women in developed countries and is associated with adverse pregnancy outcomes. However, due to the heterogeneity of CKD and evolving and advances in therapy, it is uncertain if poor outcomes are associated with any specific maternal characteristics. Understanding these differences will allow improved identification, intervention and prognostication for women with CKD.

Methods

Al Khalaf et al 1 used population data linkage methods to address these knowledge gaps. The primary database was the Swedish Medical Birth Registry (MBR) which contains prenatal and birth information for nearly all births (>99%) in Sweden since 1973 and linked to hospitalisation data from the Swedish National Patient Register (NPR). Data for diagnoses of chronic hypertension (CH) and CKD were obtained from the MBR and NPR using International Classification of Diseases (ICD) codes. Information about CKD subtypes was determined from the hospital data: tubulointerstitial, glomerular/proteinuric, diabetic nephropathy, renovascular disease, congenital/malformation kidney disease (women with congenital abnormalities of the kidney and urinary tract), and unspecified CKD. The study cohort consisted of all registered births to women who had their first recorded delivery between January 1982 and December 2012. Data from 2 788 490 singleton births from 1 420 846 women born between 1982 and 2012 were analysed.

Findings

During this study, 22 397 (0.8%) infants were born to women with CKD, 13 279 (048%) to women with CH and 1079 (0.04%) to women with both CH and CKD. Over time, the prevalence of CH and CKD in pregnancy increased by >3 fold but risks did not change and were independent of maternal age, body mass index and parity. After controlling for confounders, women with CH were found to be at highest risk for pre-eclampsia (adjusted OR (aOR) 4.57, 95% CI 4.33 to 4.84) and stillbirth (aOR 1.65, 95% CI 1.35 to 2.03). Women with CKD were most at risk of non-spontaneous preterm births (aOR 2.05, 95% CI 1.92 to 2.19) and women with both conditions had the strongest associations with caesarean delivery (in-labour aOR 1.86, 95% CI 1.49 to 2.32, without labour aOR 2.68, 95% CI 2.18 to 3.28), non-spontaneous preterm birth (aoR 9.09, 95% CI 7.61 to 10.7) and small for gestation infants (aOR 4.52, 95% CI 3.68 to 5.57).

Commentary

Women with CKD, CH and other renal abnormalities should be monitored carefully during pregnancy and delivery. Multidisciplinary antenatal management, including nephrologists and obstetricians, should be provided with intensive clinical follow-up and close surveillance. Importantly, targeting a pregnancy blood pressure goal of <140/90 mm Hg is recommended women with CKD.

This is the largest epidemiological assessment of pregnancy outcomes in women over the last three decades. The study highlights the persistence of poor pregnancy outcomes in this very large and increasing population of women. Specific associations between certain subgroups of CKD, for example, preterm labour, allows early screening, identification and if needed, therapeutic interventions.

Certainly, the connection between CKD and adverse pregnancy outcomes is a vicious circle. A systematic review and meta-analysis of 23 studies of 5 769 891 participants showed that pre-eclampsia increased the risk of CKD (adjusted risk ratio (aRR) 2.11 95% CI 1.72 to 2.59), end-stage kidney disease (aRR 4.90, 95% CI 3.56 to 6.74) and any kidney-related hospitalisation (aRR 2.65, 95% CI 1.72 to 2.59).2 CKD also exerts an enormous emotional toll on the women. A review of 15 studies including 257 women showed that pregnancy in the context of CKD was associated with profound psychological burden, including fear of fetal malformations, family well-being and implications of pregnancy on their own health for example, graft loss.3

Conclusions

Future directions of research and practice need to focus on longer term maternal and childhood outcomes. The mechanisms of causality, disease severity and treatment underlying poor pregnancy outcomes need to be addressed. The role of CKD in multiple pregnancies which were not examined by this study will also need study. Finally, consideration for the emotional toll of CKD on the pregnant woman must be considered to ensure the best outcomes for both the woman and her infant.

References

Footnotes

  • Competing interests None declared.

  • Provenance and peer review Commissioned; internally peer reviewed.

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