Post Date December, 03 2023
A prospective observational study published online recently in the Journal of the American Society of Nephrology showed an increased risk of adverse pregnancy outcomes at all stages of kidney disease. However, research data also indicate that good pregnancy outcomes may be achieved in some severe cases.
The Torino Cagliari Observation Study (TOCOS) compared the pregnancy outcomes of 504 women with chronic kidney disease (CKD) and 836 matched low-risk women. The average age of CKD mothers was 31.9 years, compared to 29.9 years in the control group. The majority of participants were white, and more than half of the patients and control group participants had never given birth (56.2% and 58.1%, respectively).
Baseline evaluations included hypertension, proteinuria (>1 g/d), systemic disease, and chronic kidney disease stages. Adverse pregnancy outcomes include cesarean section, premature delivery (<37 weeks), early preterm delivery (<34 weeks), small gestational age (SGA), and neonatal intensive care unit (NICU) use; Emerging maternal hypertension, new onset or doubling of proteinuria, and changes in the stage of chronic kidney disease. In addition, the researchers evaluated a combination of general adverse outcomes in pregnancy (premature delivery, NICU use, SGA) and a combination of severe adverse outcomes (early preterm delivery, NICU, SGA).
The risk of adverse outcomes gradually increases at different stages. For CKD1 and CKD4-5, the general adverse outcome combination was 34.1% and 90.0%, respectively; The combination of severe adverse outcomes was 21.4% and 80.0%, respectively (P<. 001).
In CKD1, preterm birth is associated with baseline hypertension, systemic disease, and proteinuria. However, even after adjusting for these classic risks, CKD1 is still associated with adverse pregnancy outcomes. Even among patients without baseline hypertension, proteinuria, or systemic disease, the risk remained increased compared to the control group (odds ratio, 1.88; 95% confidence interval, 1.27-2.79).
In patients with chronic kidney disease, the cesarean section rate was 48.4% in CKD1, 70.1% in CKD2, 78.4% in CKD3, and 70.0% in CKD4-5 (P<. 001).
The preterm birth rate was 23.5% in CKD1, 50.6% in CKD2, 78.4% in CKD3, and 88.9% in CKD4-5 (P<. 001).
The use of NICU was 10.3%, 27.6%, 44.4%, and 70.0%, respectively (P<. 001).
SGA (<10%) was 13.3%, 17.9%, 18.9%, and 50.0% in each phase (P=. 023).
Generally, the combination of adverse outcomes is between 34.1% and 90.0% (P<. 001), while the combination of severe adverse outcomes is between 21.4% and 80.0% (P<. 001).
Newly diagnosed maternal hypertension was 7.9% in patients with CKD1 and 50.0% in patients with CKD4-5 (P<. 001). In patients with newly diagnosed or doubled proteinuria, 20.5% were in CKD1, while 70.0% were in CKD4-5 (P<. 001).
The risk of intrauterine death did not differ significantly between patients with chronic kidney disease and the control group.
Research data indicate that pregnancy related risks gradually increase from CKD1 to CKD4-5. It is also interesting to note that there is a significant increase in risk from CKD1 to CKD2. This indicates that there are some "gray" areas of renal function.
The TOCOS study differs from the conclusions of a population study conducted in 2009, which suggested that a slight decrease in glomerular filtration rate does not increase additional risk.
The clinical definition of chronic kidney disease is more complex than purely assessing glomerular filtration rate.
Pregnant women with CKD, even if they do not have high-risk factors, should also pay great attention. Research results suggest that even minor kidney diseases, such as kidney scars, transient kidney infections, and normal kidney function, should be treated with caution during pregnancy. Fortunately, patients with advanced CKD often have difficulty conceiving.
