Dr. Joseph Murray, who later received the Nobel Prize for performing the first successful kidney transplant, published the first report of pregnancy in transplant recipients in the NEJM [1]. Physicians at that time were worried about the safety of pregnancy in women with kidney transplants and cautioned physicians that there might be significant risks associated with pregnancy in maternal transplant recipients [2, 3]. Despite these early warnings, pregnancy in women with kidney transplants became commonplace. As pregnancy became more common though the care of the pregnant transplant recipient became guided by opinion-based practice, rather than established guidelines [4, 5]. To date we still do not have established guidelines for the care of pregnant transplant recipients or their offspring exposed to immunosuppressive medications in utero.

Despite the lack of established guidelines, several registries have evolved to collect outcome data about reproductive issues in renal transplant recipients. These registries have developed both within the United States and throughout the world and provide important information about outcomes for both female and male transplant recipients. The way we manage pregnancy is based on information derived from reports from these voluntary registry data as well as from multi- and single-center reports, many of which rely on retrospective data.

In the United States, the National Transplantation Pregnancy Registry (NTPR) is the predominant source of information on pregnancy outcomes. The registry publishes outcomes on an annual basis and over 2,000 recipients reporting over 3,300 pregnancies have participated in the registry (www.​ntpr.​giftoflifeinstit​ute.​org). The NTPR relies on voluntary reporting by either the patient or the physician caring for the patient.

Another registry that had previously provided a great deal of information on pregnancy outcomes was the United Kingdom Transplant Pregnancy Registry. This registry directly sought voluntary information from obstetrical units and aggressively collected data from 1992 to 2001. Another voluntary registry that provided important information was the European Dialysis and Transplant Association (EDTA) Registry. The EDTA Registry collected pregnancy data from 1960 to 1992, and recently began to collect data on pregnancies that occurred between 2007 and 2011 through the DIAlysis and Pregnancies in EuRope (DIAPER) study (www.​era-edta-reg.​org).

Other registries have evolved since these early ones, including registries that continue to provide information about pregnancy collected through the Australia and New Zealand Dialysis and Transplant Registry (www.​anzdata.​org.​au) and several reports have come from centers participating in the Saudi Center for Organ Transplantation (www.​scot.​org.​sa). At this time numerous other registries have developed to study outcomes in maternal transplant recipients and their offspring that are funded by pharmaceutical companies interested in evaluating the short- and long-term risks of their medications during pregnancy.

Fertility is decreased for both women and men on dialysis [6–8]. Women are often anovulatory, although it is reversed soon after transplantation [9, 10]. Women have been reported to become pregnant soon after transplantation and there are reports of early pregnancy occurring, due to rapid resumption of ovulation in the successfully transplanted patient [11–15]. Men are often infertile as well, due to defects in gonadal function, and their fertility is improved by transplantation [16]. Whether fertility is resumed to normal after transplantation is not known and data on the use of assisted reproduction in transplant recipients is evolving.

As our patients are waiting longer for deceased donor transplants, we are faced with women aging through their ideal reproductive years. In fact women with ESRD reach menopause at an earlier age than women with normal renal function [8]. Since patients are generally waiting longer to receive a deceased donor transplant, women are usually older when they undergo transplantation, and therefore conception can be challenging for the older female transplant recipient. This should be considered in counseling the female transplant recipient considering pregnancy. Men wishing to father children should not be prescribed sirolimus as there are several reports of infertility associated with sirolimus [17–19].

The female transplant recipient should become pregnant in a planned manner. The recommendations are that pregnancy is delayed for a year after successful transplantation [5]. This recommendation replaces an earlier one that advised women to wait for 2 years after their transplant to become pregnant. It has now been recognized that newer immunosuppressive medications have decreased the risk of rejection and that allograft function is usually stable by 1 year in the uncomplicated renal transplant recipient. The American Society of Transplantation recommends that pregnancy could be safe in the first year as long as the following caveats were considered: graft function was stable, with no evidence of rejection; allograft function was good (defined as a serum creatinine <1.5 and less than 500 mg protein excreted per 24 h); that the patient was not currently taking teratogenic medications (such as valganciclovir); there were no active infections with agents that could adversely impact the fetus (such as CMV); and that the allograft function was stable. Since the reproductive phase is shortened for women with ESRD, and patients are waiting longer for deceased donor organs, the risk of waiting for 2 years after transplantation to become pregnant is that the patient may no longer be fertile. There are several recent reports that suggest that the rate of spontaneous abortion might be higher in pregnancies planned before 2 years, although this is an area of controversy [24–26].