More frequent and longer dialysis sessions should be considered for women with kidney failure who are pregnant or who wish to conceive, according to the findings of a recent study.

Pregnancy is rare in women with end-stage renal disease (ESRD) and is often accompanied by significant maternal and fetal morbidity and even mortality, Michelle A. Hladunewich, MD, of Sunnybrook Health Sciences Centre in Toronto, and fellow researchers noted in Journal of the American Society of Nephrology. After preliminary data from the Toronto Nocturnal Hemodialysis Program suggested that increased clearance of uremic toxins by intensified hemodialysis (HD) improves pregnancy outcomes, Dr. Hladunewich and associates explored the matter further.

The investigators compared the outcomes of 22 pregnancies in the Toronto Pregnancy and Kidney Disease Clinic and Registry (2000–2013), 18 of which occurred after dialysis had been initiated, with the outcomes of 70 pregnancies in the American Registry for Pregnancy in Dialysis Patients (1990-2011), four of which occurred after the start of dialysis. In Toronto, young women undergo a mean 43 hours of dialysis per week, compared with a mean 17 hours per week for young women in the U.S.

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The live birth rate was significantly higher in the Canadian cohort than in the American cohort (86.4% vs. 61.4%). In women with established kidney failure at conception, live birth rates were 83% for the Toronto patients, compared with just 53% in the American group.

Dr. Hladunewich’s team also found the following:

  • Among women with established ESRD, median duration of pregnancy in the more intensively dialyzed Toronto cohort was 36 weeks compared with 27 weeks for the American women
  • A dose response between dialysis intensity and pregnancy outcomes emerged: Live birth rates were 48% among women who had been dialyzed for at least 20 hours per week and 85% among women who underwent dialysis for more than 36 hours per week
  • Babies born to women who underwent dialysis for more than 20 hours per week had healthier birth weights than did babies born to women who had been dialyzed for 20 hours a week or less

With pregnancy complications deemed few and manageable, the researchers concluded that pregnancy may be safe and feasible in women with ESRD receiving intensive HD.