To analyze the risk factors of preterm delivery at less than 34 weeks in renal transplant recipients.

The renal transplant recipients who delivered successfully in the First Affiliated Hospital, Zhejiang University School of Medicine from January 2013 to December 2020 were retrospectively analyzed. A total of 57 recipients were enrolled in the study. According to whether the pregnancy time was more than 34 weeks, the recipients were divided into ≤34 weeks delivery group (n=21) and >34 weeks delivery group (n=36). The indexes including primary disease, the time interval between the transplantation and the pregnancy, gestational age, blood concentration of immunosuppressant during pregnancy, mode of delivery, percentile of neonatal birth weight, and Apgar score were observed. The measurement data conforming to normal distribution were compared by group t test, the counting data were compared by Chi-square test, and the risk factors of preterm delivery at less than 34 weeks were analyzed by logistic regression. A P<0.05 was considered statistically significant.

The average age of 57 recipients at gestation was (31±4) years (24-42 years), and the average interval from renal transplant to pregnancy was (44 ± 23) months (14-104 months). All cases were delivered by cesarean section, the average gestational week was (34.2±2.2) (27.7-37.7), and the average Apgar score at birth was (8.4±1.9) (1.0-10.0). The Apgar score of newborns in the >34 weeks delivery group was higher than that in the ≤ 34 weeks delivery group [(8.9±1.0) vs (7.4±2.6)], and the difference had statistical significance (t=3.17, P<0.05). There were no significant difference in gestational age, the time interval between the transplantation and the pregnancy, percentile of neonatal birth weight between the two groups (t=-1.28, 0.25, and -0.68, all P>0.05). There were no significant difference in the proportion of renal transplant recipients with gestational age <32 years (77.8%) and the interval between transplantation and pregnancy <48 months (66.7%) between the group of >34 weeks and the group of ≤34 weeks (81.0% and 71.4%) (χ²= 0.08, 0.14, all P>0.05). The proportion of serum creatinine <1.5 mg/dL during pregnancy (94.4%) was lower than that in the ≤34 weeks delivery group (66.7%), and the difference was statistically significant (χ²=7.70, P<0.05). There were no significant difference in the proportion of pre-pregnancy proteinuria and pre-gestational hypertension (χ²=0.15, 1.13, all P>0.05). The differences of gestational hypertension and gestational diabetes mellitus between the two groups were statistically significant (χ²=4.51, 7.54, all P<0.05). Logistic regression analysis showed that the gestational hypertension, gestational diabetes mellitus, and gestational gestational serum creatinine >1.5 mg/dL were risk factors for premature infants with delivery ≤34 weeks in renal transplant recipients (OR=8.661, 12.684 and 21.562, all P<0.05).

Gestational hypertension, gestational diabetes mellitus, and gestational serum creatinine increase are associated with premature infants with delivery before 34 weeks in renal transplant recipients.