Prevalence of major malformations and small for gestational age in newborns of female transplant recipients on tacrolimus-containing regimens during pregnancy

In female transplant recipients, immunosuppressant use during pregnancy raises potential concerns about adverse maternal and fetal outcomes. This noninterventional study used prospectively and retrospectively reported cases from the Transplant Pregnancy Registry International database from 1991 until 2020. The study used 2 separate cohorts to evaluate the prevalence of major malformations and small for gestational age (SGA), respectively, among live-born infants of female kidney or liver transplant recipients receiving tacrolimus-containing regimens (Tac) or non-tacrolimus-containing regimens (non-Tac). There were 1988 pregnancies (2056 livebirths) in the cohort used to assess the prevalence of malformations and 2172 pregnancies (2248 livebirths) in the cohort used to assess the prevalence of SGA. Prevalence of major malformations was similar in Tac and non-Tac groups: 2.0% and 1.9% in prospectively reported cases, and 4.7% and 3.1% in retrospectively reported cases, respectively (overall adjusted odds ratio, 1.10; 95% confidence interval, 0.68, 1.81). There was a lower prevalence of SGA in the Tac group than in the non-Tac group: 17.9% and 32.2% in prospectively reported cases and 18.1% and 23.5% in retrospectively reported cases, respectively (overall odds ratio, 0.70; 95% confidence interval, 0.57, 0.87). The use of tacrolimus in female transplant recipients was not associated with a high risk of major malformations or SGA in live-born infants.