Pregnancy in the first two years after renal transplantation increases graft loss risk, data show


TORONTO—Women who become pregnant in the first or second year after kidney transplantation are placing themselves at a significant risk of graft loss, a study of data from the United States Renal Data System (USRDS) has confirmed.

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Nephrologists should consider counseling their female patients who wish to become pregnant to wait until at least the third year post-transplantation to try to conceive rather than following the current American Society of Transplantation consensus guidelines on pregnancy.


The guidelines state that pregnancy after the first year may be reasonable in women who meet a number of criteria, such as stable graft function and immunosuppression, no or minimal proteinuria, and no rejection within one year.


Women who become pregnant in their first year after transplantation had a twofold higher risk of death-censored graft loss compared with those who become pregnant in their third year post-transplant. In a multivariate analysis, women who became pregnant in their second post-transplant year had an 82% higher risk, researchers reported here at the 2008 American Transplant Congress.


“Based on our results, we feel that it may be better for women who have the option of delaying conception until the third year post-transplant, such as younger women, to do so,” said lead investigator Nadia Zalunardo, MD, clinical assistant professor of nephrology at the University of British Columbia in Vancouver.


“However, since we do not have data on proteinuria, and our analyses are not adjusted for acute rejection, it is difficult for us to comment any more specifically on the implications of our study on current guidelines. It may still therefore be reasonable for women to attempt conception in the second year after transplantation.”


Commenting on the new study, Goran Klintmalm, MD, PhD, chairman of the Baylor Transplant Institute at the Baylor University Medical Center in Dallas, said he “strongly” agrees that it may be advisable for most women to wait until their third post-transplantation year to become pregnant.


“Any pregnancy in an organ recipient is a high-risk pregnancy that should be cared for by physicians/surgeons with considerable experience with these types of patients,” Dr. Klintmalm added.


The investigators examined data from the USRDS between January 1, 1990 and December 31, 2003 on 530 first pregnancies in the first three years after kidney-only transplantation in 483 Medicare-insured women. They estimated the date of conception using the assumptions that a full-term pregnancy is 37 weeks, a pre-term delivery is 33 weeks, and that all abortions and ectopic pregnancies are associated with 12 weeks of pregnancy.


The researchers assessed long-term survival among 455 women who survived at least two years post-transplant and became pregnant to determine the effect of timing on survival among pregnant women only. They also compared survival among women who became pregnant with 15,712 non-pregnant women in the USRDS database.


Women who become pregnant in their first or second year after transplantation have significantly shorter graft survival compared with those who become pregnant in their third year, with probability of 12-year survival of approximately 32% and 53%, respectively, in the unadjusted survival analysis.