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Is pregnancy safe after kidney transplant?

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Since the first successful pregnancy in a kidney transplant recipient in 1958,1 hundreds of kidney recipients have had successful pregnancies. Chronic kidney disease disrupts the hypothalamic-pituitary-gonadal axis, lead­ing to anovulation and infertility. However, within 6 months of kidney transplant, the hypothalamic-pituitary-gonadal axis and sex hormone levels return to normal,2 and the renal allograft is able to adapt to the various physiologic changes of pregnancy.3

Successful pregnancy after kidney transplant requires a team approach to care that includes the primary care physician, a transplant nephrologist, and an obstetrician with expertise in high-risk pregnancies. But equally important is educating and counseling the patient about the risks and challenges. This should begin at the first pretransplant visit.4

Below are answers to questions often asked by renal transplant recipients who wish to become pregnant.

WHAT IS THE IDEAL TIME TO BECOME PREGNANT AFTER KIDNEY TRANSPLANT?

Criteria for pregnancy after renal transplant
According to American Society of Transplantation and European best-practice guidelines, as outlined in Table 1, the ideal time to conceive is 1 to 2 years after renal transplant if graft function is stable, proteinuria is minimal, there are no recent episodes of acute rejection, and the patient is not taking teratogenic medications. Because transplant recipients take teratogenic immunosuppressive drugs such as mycophenolate mofetil, women should be counseled to start contraception as soon as possible after kidney transplant.5,6

Mycophenolate mofetil and sirolimus are contraindicated in pregnancy and should be stopped at least 6 weeks before conception. Mycophenolate mofetil increases the risk of congenital malformations and spontaneous abortion. Data on sirolimus from clinical studies are limited, but in animal studies it is associated with delay in ossification of skeletal structure and with an increase in fetal mortality.7

WHAT INCREASES THE RISK OF A POOR PREGNANCY OUTCOME AFTER RENAL TRANSPLANT?

Risk factors for poor maternal and fetal outcomes include an elevated prepregnancy serum creatinine level (≥ 1.4 mg/dL), hypertension, and proteinuria (≥ 500 mg/24 hours). Younger age at transplant and at conception is associated with better pregnancy outcome.5,8

WHAT ARE THE POSSIBLE MATERNAL COMPLICATIONS?

Kidney transplant recipients who become pregnant have a risk of developing preeclampsia 6 times higher than normal, and the incidence rate ranges between 24% and 38%.9,10 The risk of cesarean delivery is 5 times higher than in the general population, and the incidence rate is 43% to 64%.10,11

Low-dose aspirin reduces the risk of preeclampsia and should be prescribed to all pregnant women who are kidney transplant recipients. Angiotensin-converting enzyme inhibitors are contraindicated due to the risk of teratogenic effects, ie, pulmonary hypoplasia and oligohydramnios.4

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