The Effect of Pregnancy on the Long-term Risk of Graft Loss, Cardiovascular Disease, and Death in Kidney Transplanted Women in Norway: A Retrospective Cohort Study.

BACKGROUND: Kidney transplant recipients have now conceived for almost 50 years. Nevertheless, few studies have evaluated long-term health outcomes for kidney transplanted women after pregnancies.

METHODS: We conducted a retrospective cohort study of all Norwegian women receiving a kidney transplant before the age of 50 years between 1969 and 2013, with graft loss, cardiovascular disease, and death as outcomes. Baseline characteristics for all women were ascertained at first transplantation, with information about exposure, outcomes, and potential confounders collected from medical records. To account for changes in pregnancy status, data were analyzed using proportional hazard Cox regression with pregnancy status as a time-dependent covariate changing at the time of pregnancy.

RESULTS: Of 650 women studied, 124 had a pregnancy after kidney transplantation. During the study period, graft loss, cardiovascular disease, and death occurred in 237, 73, and 274 women, respectively. Pregnancy was associated with 54% lower risk of graft loss (95% confidence interval [CI]: 25% to 71%) and 72% lower risk of death (95% CI, 53%-84%). Adjusting for possible confounders had a minimal impact on estimated values. There were considerable uncertainties and no statistically significant results regarding the estimated risk of cardiovascular disease after pregnancy (univariate hazard ratio, 0.91; 95% CI, 0.43-1.92; multivariate hazard ratio, 0.71; 95% CI, 0.32-1.60).

CONCLUSIONS: Kidney transplanted women with pregnancies have a low risk of subsequent graft loss or death. These results are reassuring for the current clinical practice.