Pregnancy outcomes for kidney transplant recipients with transplantation as a child.

IMPORTANCE: Pregnancy outcomes for women who received a kidney transplant in childhood are uncertain.

OBJECTIVES: To report pregnancy outcomes for women with kidney transplantation in childhood (aged <18 years; child-tx mothers) and to compare them with those for women who received a kidney transplant in adulthood (aged ≥18 years; adult-tx mothers).

DESIGN, SETTING, AND PARTICIPANTS: Observational cohort study in Australia and New Zealand of all women with a functioning kidney transplant included in the Australia and New Zealand Dialysis and Transplant Registry for whom at least 1 pregnancy was reported between January 1, 1963, and December 31, 2012.

MAIN OUTCOMES AND MEASURES: Pregnancy outcomes including live birth rates, gestational age, and proportion of babies who are small for gestational age.

RESULTS: A total of 101 pregnancies in 66 child-tx mothers and 626 pregnancies in 401 adult-tx mothers were reported. At the time of pregnancy, child-tx mothers had a mean age of 25 (95% CI, 24-26) years with a functioning transplant for 10 (95% CI, 9-11) years, while adult-tx mothers had a mean age of 31 (95% CI, 31-31) years with a functioning transplant for 6 (95% CI, 5-6) years (both P < .001). Live births occurred in 76% of pregnancies in child-tx mothers and 77% of pregnancies in adult-tx mothers. The mean gestational ages were similar between child-tx and adult-tx mothers (35 [95% CI, 33-37] vs 36 [95% CI, 35-36] weeks, respectively; P = .68). The incidence of prematurity (<37 weeks' gestation) was also similar (child-tx mothers, 45%; adult-tx mothers, 53%). A similar proportion of preterm babies born to child-tx and adult-tx mothers were small for gestational age (22% vs 10%, respectively; odds ratio [OR] = 2.53 [95% CI, 1.13-5.69]). Term babies born to child-tx and adult-tx mothers were frequently small for gestational age (57% vs 38%, respectively; OR = 2.16 [95% CI, 1.23-3.81]), both significantly more frequently than babies born at term in the general population (child-tx mothers, OR = 11.93 [95% CI, 5.56-25.61]; adult-tx mothers, OR = 5.52 [95% CI, 2.56-11.89]).

CONCLUSIONS AND RELEVANCE: Pregnancy outcomes for child-tx mothers are similar to those for adult-tx mothers, with no difference in the rate of live births, gestational age, or small for gestational age. Regardless of when women received their kidney transplant, their pregnancies are likely to result in a live, albeit preterm, birth. This work should provide comfort to child-tx mothers and their physicians that their early onset of kidney failure and longer period of transplantation and immunosuppression do not adversely affect their pregnancy outcomes compared with adult-tx mothers.