Chronic kidney disease (CKD) may complicate 3% of pregnancies, with 1 in 750 pregnancies in women with CKD stages 3-5. It is a risk factor for adverse outcomes, including preterm delivery, fetal growth restriction, and maternal renal function reduction. Although all stages of CKD have been shown to raise the risk of adverse pregnancy outcomes compared with women without CKD. 

A retrospective cohort study demonstrated that women with CKD 3-5 have a high live birth rate in pregnancies beyond 20 weeks gestation, but pregnancies are complicated by preterm delivery and birth weight <10th centile. It is an established fact that pre-pregnancy CKD stages 3-5 are linked with a raised risk of adverse pregnancy outcomes in small and previous historical cohorts. There is no clarity between the interaction between chronic hypertension, proteinuria, and renal excretory function. 

The study results showed that contemporary pregnancies in women with CKD stage 3-5 are complicated preterm delivery, low birthweight, and loss of maternal renal function. Pregnancy in women with CKD stages 3-5 raises the need for dialysis or transplantation by 2.5 years. 

The results of this study have suggested that chronic hypertension is a strong predictor of delivery before 34 weeks gestation, and pre-or early pregnancy proteinuria increases the chance of birth weight below the 10th centile. The study also concluded that the pregnancy-associated decline in renal function is more in women with chronic hypertension and in those with a gestational reduction in serum creatinine level that is under 10% of pre-pregnancy concentrations and the effect of pregnancy is equivalent to 1.7, 2.1, and 4.9 years of pre-pregnancy renal disease in CKD stages 3a, 3b and 4-5 respectively. 

Reference: 

1. Wiles K, Webster P, Seed PT, et al. the impact of chronic kidney disease stages 3-5 on pregnancy outcomes. Nephrol Dial transplant. 2020: 1-10.