Maternal and fetal outcomes of pregnancies in kidney donors: A 30-year comparative analysis of matched non-donors in a single center

Pregnancy Outcomes in Living Kidney Donors: Protocol of a Population-Based Cohort Study in Three Canadian Provinces

Background

A substantial proportion of living kidney donors are women of childbearing age. Some prior studies report a higher risk of gestational hypertension and pre-eclampsia in living kidney donors compared with nondonors. Further research is needed to better quantify the risk of adverse maternal, fetal/infant, and neonatal outcomes attributable to living kidney donation.

Objective

To determine the risk of hypertensive disorders of pregnancy, including gestational hypertension, pre-eclampsia, and eclampsia, and other maternal and fetal/infant outcomes in living kidney donors compared with a matched group of nondonors of similar baseline health.

Design and Setting

Protocol for a population-based, matched cohort study using Canadian administrative health care databases. The protocol will be run separately in 3 provinces, Ontario, Alberta, and British Columbia, and results will be combined statistically using meta-analysis.

Participants

The cohort will include women aged 18 to 48 years who donated a kidney between July 1992 and March 2022 and had at least one postdonation singleton pregnancy of ≥20 weeks gestation between January 1993 and February 2023. We expect to include at least 150 living kidney donors with over 200 postdonation pregnancies from Ontario and a similar number of donors and pregnancies across Alberta and British Columbia combined. Nondonors will include women from the general population with at least one pregnancy of ≥20 weeks gestation between January 1993 and February 2023. Nondonors will be randomly assigned cohort entry dates based on the distribution of nephrectomy dates in donors. The sample of nondonors will be restricted to those aged 18 to 48 years on their cohort entry dates with delivery dates at least 6 months after their assigned entry dates. A concern with donor and nondonor comparisons is that donors are healthier than the general population. To reduce this concern, we will also apply 30+ exclusion criteria to further restrict the nondonor group so that they have similar health measures at cohort entry as the donors. Donor and nondonor pregnancies will then be matched (1:4) on 5 potential confounders: delivery date, maternal age at delivery date, time between cohort entry and delivery date, neighborhood income quintile, and parity at delivery date.

Measurements

The primary outcome will be a composite of maternal gestational hypertension, preeclampsia, or eclampsia. Secondary maternal outcomes will include components of the primary outcome, early pre-eclampsia, severe maternal morbidity, cesarean section, postpartum hemorrhage, and gestational diabetes. Fetal/infant/neonatal outcomes will include premature birth/low birth weight, small for gestational age, neonatal intensive care unit admission, stillbirth, and neonatal death.

Methods

The primary unit of analysis will be the pregnancy. We will compute the risk ratio of the primary composite outcome in donors versus nondonors using a log-binomial mixed regression model with random effects to account for the correlation within women with multiple pregnancies and within matched sets of donors and nondonors. We will perform the statistical analyses within each province and then combine aggregated results using meta-analytic techniques to produce overall estimates of the study outcomes.

Limitations

Due to regulations that prevent individual-level records from being sent to other provinces, we cannot pool individual-level data from all 3 provinces.

Conclusion

Compared to prior studies, this study will better estimate the donation-attributable risk of adverse maternal, fetal/infant, and neonatal outcomes. Transplant centers can use the results to counsel female living donor candidates of childbearing age and to inform recommended practices for the follow-up and care of living kidney donors who become pregnant.

Worsening of Diabetes Control Measures and Decreased Kidney Function in Pre-Diabetic Kidney Donors Compared to Non-Diabetic Donors Whose BMI Before Kidney Donation was Above 30

BACKGROUND

The incidence of end-stage renal disease has increased dramatically over the past two decades. Kidney transplantation is the best treatment option for individuals with end-stage renal disease, and living donor kidney transplantation has significant advantages over deceased donor kidney transplantation. Although there are criteria for assessing living kidney donors, different medical centers handle certain medical problems differently. The aim of this study is to investigate how kidney donation affects renal biochemical indicators, blood pressure measurements, and glucose control in healthy young female adults without diabetes compared to a pre-diabetic group.

METHODS

A prospective cohort study recruited 142 female kidney donors, who were divided into two cohorts based on their diabetic history (pre-diabetic and non-diabetic). The participants were monitored for seven years after kidney donation. Key clinical and biochemical markers were measured before and after donation.

RESULTS

The pre-diabetic group had higher mean values for blood pressure readings, body mass indices, Oral Glucose Tolerance Test, HbA1c (DCCT) (%), serum creatinine levels, proteinuria, and lower e-GFR compared to those in the non-diabetic group. All these findings were statistically significant.

CONCLUSIONS

Pre-diabetic donors are at an increased risk for many adverse clinical and biochemical outcomes, including hypertension, glucose tolerance, and worsening kidney function tests and should be advised that their condition may worsen over time and can result in end-organ complications. If the donors decide to proceed, they should be closely and frequently monitored during both the short- and long-term periods.

Pregnancy in Living Kidney Donors: An Evidence-Based Review

Purpose of review

To review the current studies and guidelines on the risk of adverse pregnancy outcomes in female kidney donors.

Recent findings

Living kidney donors include a significant amount of young women of child-bearing age. Safety and possible risks of pregnancy after donation are a concern for female kidney donor candidates. Many current studies indicate a higher risk of preeclampsia in women after kidney donation. Considering the increasing number of living kidney donors, the maternal outcomes of living kidney donation is an active area of research.

Summary

Guidelines and consensus statements on the risk of pregnancy in living kidney donors recommend close monitoring of blood pressure, weight gain, and proteinuria during pregnancy. Current studies indicate an increased risk of hypertensive disorders of pregnancy in living kidney donors. Counseling and informing donor candidates about the possible risks is important.

Long-term Outcomes Associated With Post-kidney Donation Pregnancy Complications

BACKGROUND

Kidney donors have increased risk of postdonation gestational hypertension (gHTN) and preeclampsia. In the general population, pregnancy complications are associated with long-term maternal risk. However, little data exist on whether donors with postdonation pregnancy-related complications have similar increased long-term risks. We studied whether postdonation gHTN, preeclampsia/eclampsia, or gestational diabetes (gDM) was associated with increased risk of developing hypertension, DM, cardiovascular disease, or estimated glomerular filtration rate <45 mL/min/1.73 m 2 .

METHODS

Postdonation pregnancies with complications were matched to pregnancies without complications based on time from donation. Incidence of outcomes was compared using sequential Cox regression with robust standard errors. Donors with predonation pregnancy complications were excluded. Models were adjusted for age at pregnancy, gravidity, year of donation, and family history of hypertension, DM, and heart disease.

RESULTS

Of the 384 donors with postdonation pregnancies (median [quartiles] follow-up of 27.0 [14.2-36.2] y after donation), 39 experienced preeclampsia/eclampsia, 29 gHTN without preeclampsia, and 17 gDM. Median interval from donation to first pregnancy with preeclampsia was 5.1 (2.9-8.6) y; for gHTN, 3.7 (1.9-7.8) y; and for gDM, 7.3 (3.7-10.3) y. Preeclampsia/eclampsia (hazard ratio [HR] 2.70; 95% confidence interval [CI], 1.53-4.77) and gHTN (HR 2.39; 95% CI, 1.24-4.60) were associated with development of hypertension. Preeclampsia/eclampsia (HR 2.15; 95% CI, 1.11-4.16) and gDM (HR 5.60; 95% CI, 1.41-22.15) were associated with development of DM. Pregnancy-related complications were not associated with increased risk of cardiovascular disease or estimated glomerular filtration rate <45 mL/min/1.73 m 2 .

CONCLUSIONS

In our single-center study, postdonation preeclampsia, gHTN, or gDM was associated with long-term risk of hypertension or DM.

Pregnancy After Kidney Donation: The Experience in a Cohort of Portuguese Living Donors

BACKGROUND

Living kidney donation (LKD) is a preferred treatment option for end-stage chronic kidney disease, but it can also pose potential risks for the donor, including hypertension and end-stage renal disease. Many donors are women of reproductive age who may have concerns about the effects of donation on future pregnancies. The aim of this study was to determine fetal and maternal outcomes in a cohort of pregnancies after LKD and to compare them with pregnancies before LKD.

METHODS

We conducted a retrospective analysis of living kidney donors of childbearing age (<46 years old) at the time of donation who got pregnant after LKD in our center between 1987 and 2020 (N = 13). Clinical data were collected, including demographic characteristics and maternal and fetal outcomes.

RESULTS

We observed 16 pregnancies after LKD and 12 pregnancies before LKD in the same group of patients. The rate of gestational hypertension was 12.5% in pregnancies after LKD and 8.3% before LKD (P = .999). There were 13 successful pregnancies after LKD with a mean gestational age of 38.6 ± 1.7 weeks. There were no episodes of acute kidney injury or other complications.

CONCLUSION

The present study suggests that LKD does not have a negative effect on maternal and fetal outcomes. However, caution should be taken due to the small sample size. We agree with the guidelines recommending close monitoring of post-donation pregnancies.

The Minnesota attributable risk of kidney donation (MARKD) study: a retrospective cohort study of long-term (> 50 year) outcomes after kidney donation compared to well-matched healthy controls

BACKGROUND

There is uncertainty about the long-term risks of living kidney donation. Well-designed studies with controls well-matched on risk factors for kidney disease are needed to understand the attributable risks of kidney donation.

METHODS

The goal of the Minnesota Attributable Risk of Kidney Donation (MARKD) study is to compare the long-term (> 50 years) outcomes of living donors (LDs) to contemporary and geographically similar controls that are well-matched on health status. University of Minnesota (n = 4022; 1st transplant: 1963) and Mayo Clinic LDs (n = 3035; 1st transplant: 1963) will be matched to Rochester Epidemiology Project (REP) controls (approximately 4 controls to 1 donor) on the basis of age, sex, and race/ethnicity. The REP controls are a well-defined population, with detailed medical record data linked between all providers in Olmsted and surrounding counties, that come from the same geographic region and era (early 1960s to present) as the donors. Controls will be carefully selected to have health status acceptable for donation on the index date (date their matched donor donated). Further refinement of the control group will include confirmed kidney health (e.g., normal serum creatinine and/or no proteinuria) and matching (on index date) of body mass index, smoking history, family history of chronic kidney disease, and blood pressure. Outcomes will be ascertained from national registries (National Death Index and United States Renal Data System) and a new survey administered to both donors and controls; the data will be supplemented by prior surveys and medical record review of donors and REP controls. The outcomes to be compared are all-cause mortality, end-stage kidney disease, cardiovascular disease and mortality, estimated glomerular filtration rate (eGFR) trajectory and chronic kidney disease, pregnancy risks, and development of diseases that frequently lead to chronic kidney disease (e.g. hypertension, diabetes, and obesity). We will additionally evaluate whether the risk of donation differs based on baseline characteristics.

DISCUSSION

Our study will provide a comprehensive assessment of long-term living donor risk to inform candidate living donors, and to inform the follow-up and care of current living donors.

Pregnancy outcomes after living kidney donation from a nationwide population-based cohort study from Korea

While most living kidney donors experience good outcomes and high rates of satisfaction, kidney donation can increase the risk of gestational hypertension or preeclampsia. However, pregnancy outcomes in non-white donors are limited. We conducted a nationwide cohort study of 112 living kidney donors and 672 matched healthy non-donors using the Korean National Health Insurance Claims Database. Donors and healthy non-donors were matched according to age, year of cohort entry, residency, income, number of pregnancies, and the time to the first pregnancy after cohort entry. We assessed pregnancy outcomes of live kidney donors compared with matched healthy non-donors using the nationwide database. Gestational hypertension or preeclampsia was more common in kidney donors than in non-donors (8.9% vs. 1.8%; adjusted odds ratio, 2.68; 95% confidence interval, 1.11-6.50). However, the incidence of severe gestational hypertension or preeclampsia that required antihypertensive medication was comparable (2.7% vs. 0.9%; P = 0.121). The time from donation to delivery within 5 years and primiparity were risk factors for preeclampsia in donors. Low birth weight, stillbirth, and ectopic pregnancy were not significantly different between the two groups. Maternal death occurred in two non-donor cases, but none occurred in donors compared to non-donors. Our findings indicate that kidney donors are associated with an increased risk of gestational hypertension or preeclampsia than matched healthy non-donors. However, the probabilities of serious maternal and fetal outcomes remained low and are not increased significantly after kidney donation.

Recommendations for living donor kidney transplantation

This Guide for Living Donor Kidney Transplantation (LDKT) has been prepared with the sponsorship of the Spanish Society of Nephrology (SEN), the Spanish Transplant Society (SET), and the Spanish National Transplant Organization (ONT). It updates evidence to offer the best chronic renal failure treatment when a potential living donor is available. The core aim of this Guide is to supply clinicians who evaluate living donors and transplant recipients with the best decision-making tools, to optimise their outcomes. Moreover, the role of living donors in the current KT context should recover the level of importance it had until recently. To this end the new forms of incompatible HLA and/or ABO donation, as well as the paired donation which is possible in several hospitals with experience in LDKT, offer additional ways to treat renal patients with an incompatible donor. Good results in terms of patient and graft survival have expanded the range of circumstances under which living renal donors are accepted. Older donors are now accepted, as are others with factors that affect the decision, such as a borderline clinical history or alterations, which when evaluated may lead to an additional number of transplantations. This Guide does not forget that LDKT may lead to risk for the donor. Pre-donation evaluation has to centre on the problems which may arise over the short or long-term, and these have to be described to the potential donor so that they are able take them into account. Experience over recent years has led to progress in risk analysis, to protect donors' health. This aspect always has to be taken into account by LDKT programmes when evaluating potential donors. Finally, this Guide has been designed to aid decision-making, with recommendations and suggestions when uncertainties arise in pre-donation studies. Its overarching aim is to ensure that informed consent is based on high quality studies and information supplied to donors and recipients, offering the strongest possible guarantees.

Long-term Medical Outcomes of Living Kidney Donors

Historically, to minimize risks, living kidney donors have been highly selected and healthy. Operative risks are well-defined, yet concern remains about long-term risks. In the general population, even a mild reduction in glomerular filtration rate (GFR) is associated with cardiovascular disease, chronic kidney disease, and end-stage kidney disease (ESKD). However, reduction in GFR in the general population is due to kidney or systemic disease. Retrospective studies comparing donors with matched general population controls have found no increased donor risk. Prospective studies comparing donors with controls (maximum follow-up, 9 years) have reported that donor GFR is stable or increases slightly, whereas GFR decreases in controls. However, these same studies identified metabolic and vascular donor abnormalities. There are a few retrospective studies comparing donors with controls. Each has limitations in selection of the control group, statistical analyses, and/or length of follow-up. One such study reported increased donor mortality; 2 reported a small increase in absolute risk of ESKD. Risk factors for donor ESKD are similar to those in the general population. Postdonation pregnancies are also associated with increased risk of hypertension and preeclampsia. There is a critical need for long-term follow-up studies comparing donors with controls from the same era, geographic area, and socioeconomic status who are healthy, with normal renal function on the date matching the date of donation, and are matched on demographic characteristics with the donors. These data are needed to optimize donor candidate counseling and informed consent.

Pregnancy after living kidney donation, a systematic review of the available evidence, and a review of the current guidance

Understanding and communicating the risk of pregnancy complications post-living kidney donation is imperative as the majority of living kidney donors (LKD) are women of childbearing age. We aimed to identify all original research articles examining complications in post-donation pregnancies and compared the quality and consistency of related guidelines. We searched Embase, MEDLINE, PubMed, society webpages, and guideline registries for English-language publications published up until December 18, 2020. Ninety-three articles were screened from which 16 studies were identified, with a total of 1399 post-donation pregnancies. The outcome of interest, post-donation pregnancy complications, was not calculable, and only a narrative synthesis of the evidence was possible. The absolute risk of pre-eclampsia increased from ~1%-3% pre-donation (lower than the general population) to ~4%-10% post-donation (comparable to the general population). The risks of adverse fetal and neonatal outcomes were no different between post-donation and pre-donation pregnancies. Guidelines and consensus statements were consistent in stating the need to inform LKDs of their post-donation pregnancy risk, however, the depth and scope of this guidance were variable. While the absolute risk of pregnancy complications remains low post-donation, a concerted effort is required to better identify and individualize risk in these women, such that consent to donation is truly informed.

Perception regarding live kidney donation in the general population of South Korea

This study aimed to know how the general population recognizes live kidney donation in Korea. Participants were randomly selected from the general population after proportional allocation by region, sex, and age. Selected participants received a questionnaire that included demographic information, socioeconomic and marital statuses, prior recognition of live donor kidney transplantation, expected changes after donation, and the need for support after donor nephrectomy. Among the 1,000 participants from the web-based survey, 83.8% answered they fully understood living donor kidney transplantation, 81.1% knew about them, and 51.1% were willing to donate. Various complications after nephrectomy and deterioration in health after donation were the most significant reasons for those reluctant to donate. Most agreed that the government should provide social and economic support to living kidney donors, especially after exposure to the description of donor nephrectomy. Financial support, including surgery and regular medical check-up costs, was the most preferred government support. The Korean general population seemed aware of the value and safety of kidney donation, although only half of them were willing to donate due to concerns about possible complications. Most participants agreed on social and economic support for living kidney donors, especially surgery-related costs.

Risk of pregnancy complications in living kidney donors: A systematic review and meta-analysis

Living kidney donation is associated with glomerular hyperfiltration, predisposing for the development of chronic kidney disease. The present meta-analysis aims to gather current evidence and clarify whether kidney donors are at increased risk of future pregnancy complications. Medline, Scopus, Web of Science, CENTRAL and Google Scholar were systematically searched from inception to August 29, 2021. Observational studies comparing the rates of adverse pregnancy outcomes among kidney donors and non-donors were selected. Random-effects models were fitted to provide meta-analysis estimates, while the quality of evidence was appraised with the Grading of Recommendations Assessment, Development and Evaluation approach. Five studies were included, comprising 430 donors and 23,540 non-donors. Living kidney donation was associated with significantly higher risk of preeclampsia (OR: 2.86, 95% CI: 1.62-5.05, moderate quality of evidence), gestational hypertension (OR: 2.53, 95% CI: 1.11-5.74, low quality of evidence) and preterm birth (OR: 1.32, 95% CI: 1.01-1.74, moderate quality of evidence). The anticipated absolute rates of preeclampsia, gestational hypertension and preterm birth were 7.4%, 5.4% and 8.3%, respectively. The risk of gestational diabetes, cesarean delivery, low birthweight and fetal death was similar between the two groups (low quality of evidence). In conclusion, women with history of kidney donation are at significantly increased risk of preeclampsia, gestational hypertension and preterm birth in subsequent pregnancies, although the absolute rate of complications remains below 10%. Future studies should confirm these effects and improve potential donor counseling by individualizing the risk of adverse perinatal outcomes.

Mothers' Experiences With Pregnancy and Childbirth Following Pediatric Living Liver Transplant Donation: A Qualitative Descriptive Study

BACKGROUND

Half of pediatric living liver transplantation donors are mothers, including women of reproductive age. Reports on pregnancy and childbirth after living donor liver transplantation are limited to medical aspects, and mothers' experiences remain unclear. We describe the experiences of women who became pregnant and gave birth after living donor liver transplantation.

METHODS

We used a qualitative descriptive approach. Eleven women who became pregnant and delivered following pediatric living liver transplant donation participated in face-to-face, in-depth interviews. Data collected via semi-structured interviews were assessed using an inductive qualitative analysis. The study was conducted in accordance with the Declaration of Helsinki.

RESULTS

Women's experiences with pregnancy and childbirth following pediatric living liver transplant donation were categorized as follows: explanation and consultation on pregnancy and childbirth after liver donation; physical and mental burden after liver donation; concern about the effects of donor surgery on pregnancy and childbirth; consideration for own body; concern about the physical condition of my child, who is the recipient; and the presence of health professionals with which to easily consult.

CONCLUSION

After donation, mothers are physically burdened and experiences anxiety about the physical condition of the recipient as well as about pregnancy and childbirth. Therefore, continuous psychosocial support is necessary.

Long-term Mortality Risks Among Living Kidney Donors in Korea

RATIONALE & OBJECTIVE

Living kidney donors may have a higher risk for death and kidney failure. This study aimed to investigate the long-term mortality experience of living kidney donors compared with members of the general public in Korea who underwent voluntary health examinations.

STUDY DESIGN

Cohort study.

SETTING & PARTICIPANTS

We first calculated standardized mortality ratios for 1,292 Korean living kidney donors who underwent donor nephrectomy between 1982 and 2016 and 72,286 individuals who underwent voluntary health examinations between 1995 and 2016. Next we compared survival between the 1,292 living kidney donors and a subgroup of the health examination population (n=33,805) who had no evident contraindications to living kidney donation at the time of their examinations. Last, a matched comparator group was created from the health examination population without apparent contraindication to donation by matching 4,387 of them to donors (n=1,237) on age, sex, body mass index, estimated glomerular filtration rate, urine dipstick albumin excretion, previously diagnosed hypertension and diabetes, and era.

EXPOSURES

Donor nephrectomy.

OUTCOMES

All-cause mortality and other clinical outcomes after kidney donation.

ANALYTICAL APPROACH

First, standardized mortality ratios were calculated separately for living kidney donors and the health examination population standardized to the general population. Second, we used Cox regression analysis to compare mortality between living kidney donors versus the subgroup of the health examination population without evident donation contraindications. Third, we used Cox regression analysis to compare mortality between living kidney donors and matched comparators from the health examination population without apparent contraindication to donation.

RESULTS

The living kidney donors and health examination population had excellent survival rates compared with the general population. 52 (4.0%) of 1,292 kidney donors died during a mean follow-up of 12.3±8.1 years and 1,072 (3.2%) of 33,805 in the health examiner subgroup without donation contraindications died during a mean follow-up of 11.4±6.1 years. Donor nephrectomy did not elevate the hazard for mortality after multivariable adjustment in kidney donors and the 33,805 comparators (adjusted HR, 1.01; 95% CI, 0.71-1.44; P=0.9). Moreover, living donors showed a similar mortality rate compared with the group of matched healthy comparators.

LIMITATIONS

Donors from a single transplantation center. Residual confounding owing to the observational study design.

CONCLUSIONS

Kidney donors experienced long-term rates of death comparable to nondonor comparators with similar health status.