Pregnancy and Maternal Outcomes Among Kidney Transplant Recipients

Fertility rates, pregnancy, and maternal outcomes are not well described among women with a functioning kidney transplant. Using data from the Australian and New Zealand Dialysis and Transplant Registry, we analyzed 40 yr of pregnancy-related outcomes for transplant recipients. This analysis included 444 live births reported from 577 pregnancies; the absolute but not relative fertility rate fell during these four decades. Of pregnancies achieved, 97% were beyond the first year after transplantation. The mean age at the time of pregnancy was 29 ± 5 yr. Compared with previous decades, the mean age during the last decade increased significantly to 32 yr (P < 0.001). The proportion of live births doubled during the last decade, whereas surgical terminations declined (P < 0.001). The fertility rate (or live-birth rate) for this cohort of women was 0.19 (95% confidence interval 0.17 to 0.21) relative to the Australian background population. We also matched 120 parous with 120 nulliparous women by year of transplantation, duration of transplant, age at transplantation ±5 yr, and predelivery creatinine for parous women or serum creatinine for nulliparous women; a first live birth was not associated with a poorer 20-yr graft or patient survival. Maternal complications included preeclampsia in 27% and gestational diabetes in 1%. Taken together, these data confirm that a live birth in women with a functioning graft does not have an adverse impact on graft and patient survival.One of the many perceived benefits of kidney transplantation has been restoration of pituitary-ovarian function and fertility in women of reproductive age. Prenatal advice for women with a functioning kidney transplant has been primarily based on data derived from observational research,^1–13 and the reported live-birth rates achieved in such women range from 43.2¹⁴ to 82%.¹⁵Although an increased pregnancy event number has been reported for women with a functioning kidney transplant,¹⁶ little is actually known about “pregnancy rate changes” during the past 40 yr. More importantly, long-term graft and maternal survival analyses, referred to when advising women who have undergone transplantation and are considering a pregnancy, have been mostly performed without adequate matching,¹² or, alternatively, matching has been used but outcomes followed up for only brief intervals^14,17,18 and in small cohorts.^19–22 Published graft matching studies to date suggest no adverse impact 10 yr after a live birth.¹⁴In most instances, pregnancies in women with a kidney graft have been encouraged. Historically, renal function,^8,15,17,18 baseline proteinuria,²³ intercurrent hypertension,^1,24 and time from transplantation^{1,3,5,8,14,15,18,24,25} have been used to predict adverse event risks to the mother, kidney, and offspring. To this are added the often unquantifiable inherent risks for genetically transmitted diseases or the problems associated with prematurity.^26,27 More recently, epidemiologic evidence suggests low birth weight may be associated with the development of hypertension,²⁸ cardiovascular disease,²⁹ insulin resistance,³⁰ and end-stage renal failure.³¹ Moreover, low birth weight is associated with an increased risk for hypertension, independent of genetic and shared environmental factors.³²Series published to date have not captured all pregnancy events or their outcomes. Limitations of some of the published studies include short duration of follow-up and studies with no adequate or long-term matching for decade and renal function.We examined fertility rates, pregnancy rates, and pregnancy outcomes over 40 yr in an at-risk population, defined as women who were aged between 15 and 49 and had a functioning kidney transplant, using ANZDATA registry data. In addition, maternal and graft outcomes were analyzed, and, uniquely, a matched cohort analysis of 120 nulliparous and 120 parous women who had undergone transplantation enabled analysis of outcomes at 20 yr.