Pregnancy in renal transplant recipients: a UK national cohort study.

BACKGROUND AND OBJECTIVES Most reports of pregnancy outcome in women with kidney transplants are single-center, retrospective, and include small numbers and few are compared with controls. The aim of this study was to collect information about pregnancy outcomes among all kidney transplant recipients in the United Kingdom, managed with current antenatal and nephrologic care, and to compare these data with a contemporaneous control group. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS Pregnant women with a kidney transplant were identified through the UK Obstetric Surveillance System (UKOSS) between January 1, 2007 and December 31, 2009. Data on a comparison cohort were obtained from the UKOSS database, containing information on comparison women identified in previous studies. Outcomes were also compared with national data. RESULTS There were 105 pregnancies identified in 101 recipients. Median prepregnancy creatinine was 118 μmol/L. Preeclampsia developed in 24% compared with 4% of the comparison group. Median gestation at delivery was 36 weeks, with 52% of women delivering at <37 weeks, significantly higher than the national rate of 8%. Twenty-four infants (24%) were small for gestational age (<10th centile). There were two (2%) cases of acute rejection. Potential predictive factors for poor pregnancy outcome included >1 previous kidney transplant (P=0.03), first trimester serum creatinine >125 μmol/L (P=0.001), and diastolic BP >90 mmHg in the second (P=0.002) and third trimesters (P=0.05). CONCLUSIONS Most pregnancies in the United Kingdom in women with kidney transplants are successful but rates of maternal and neonatal complications remain high.