Major adverse pregnancy outcomes linked to long-term risk of kidney disease

Major adverse pregnancy outcomes are associated with an increased long-term risk of kidney disease, according to a recent study in the American Journal of Obstetrics & Gynecology.¹

Takeaways

Women who experience adverse pregnancy outcomes such as preterm birth, small for gestational age, preeclampsia, gestational diabetes, and other hypertensive disorders have a significantly increased risk of developing chronic kidney disease (CKD) later in life.
The study suggests that all major adverse pregnancy outcomes should be considered long-term independent risk factors for CKD, emphasizing the importance of ongoing monitoring and management for these women.
The national cohort study included women with singleton deliveries recorded in the Swedish Medical Birth Register from 1973 to 2015, with follow-up extending through 2018, revealing a strong link between adverse pregnancy outcomes and CKD.
Different adverse pregnancy outcomes had varying hazard ratios for CKD, with other hypertensive disorders and gestational diabetes showing the highest risks, followed by preeclampsia, preterm delivery, and small for gestational age.
Women with adverse pregnancy outcomes often had sociodemographic risk factors such as younger age at first delivery, lower education or income, higher body mass index, and smoking, which may contribute to the increased CKD risk.

There is an association between adverse pregnancy outcomes such as small for gestational age, preterm delivery, gestational diabetes, preeclampsia, and other hypertensive disorders of pregnancy with increased renal complication risks. Additionally, up to 1 in 3 pregnancies are impacted by 1 or more adverse pregnancy outcome.

There is little data about the link between adverse pregnancy outcomes and chronic kidney disease (CKD). As CKD can progress even when treated and lead to end-stage kidney failure (ESKF),² it is vital to understand associated risk factors.

To evaluate the association between 5 major adverse pregnancy outcomes and long-term CKD risk, investigators conducted a national cohort study.¹ Women with a singleton delivery between 1973 and 2015 recorded in the Swedish Medical Birth Register were included in the analysis. Women with a prior CKD diagnosis were excluded.

Preterm birth, small for gestational age, preeclampsia, other hypertensive disorders of pregnancy, and gestational diabetes were identified as the 5 major adverse pregnancy outcomes. Data about hypertensive disorders was obtained from the Medical Birth Register.

Follow-up occurred from first delivery through December 31, 2018, with a maximum and median follow-up time of 46 and 25 years, respectively. Any CKD diagnosis after 3 months postpartum was reported as the primary outcome of the analysis. International Classification of Diseases (ICD) codes were used to identify CKD.

Since ICD codes for CKD were unavailable before 1987, deliveries before this time were not included in the sensitivity analysis. Covariates included maternal age, year of delivery, education level, parity, employment status and income, country of origin, and other CKD risk factors.

At least 1 pregnancy outcome was reported among 30.4% of women, and 2 or more by 8.3%. Small for gestational age was the most common adverse pregnancy outcome in 14.3%% of women, followed by preterm delivery in 8.8%.

Women with small for gestational age or preterm delivery were often younger at first delivery, had a lower education or income, or more often smoked.

Those with preeclampsia were more likely to have a lower education or income, had a higher body mass index (BMI), and were more likely to smoke. Finally, those with other hypertensive disorders or gestational diabetes were often older at first delivery, had a higher BMI, or were nonsmokers.

CKD was reported in 0.5% of women during follow-up and ESKD in 0.2%. Patients were aged a median 61 years at CKD diagnosis and 53 years at ESKD diagnosis, with a median follow-up time of 27 years.

All 5 major adverse pregnancy outcomes were independently associated with CKD, with a hazard ratio (HR) of 4 for other hypertensive disorders, 3.85 for gestational diabetes mellitus, 2.35 for preeclampsia, 2 for preterm delivery, and 1.25 for small for gestational age.

Infant birth weight under the fifth percentile for gestational age was also associated with increased CKD risk vs under the tenth percentile, with adjusted HRs of 1.30 and 1.25, respectively when compared to birthweight of the tenth percentile or greater.

Preterm delivery, preeclampsia, and other hypertensive disorders had the highest HRs for CKD in the first 10 years after delivery. However, the HRs for gestational diabetes mellitus were greatest at 20 to 29 years, and for small for gestational age at 10 to 19 years. HRs remained significant at 30 to 46 years after delivery.

These results indicated increased CKD risk following a major adverse pregnancy outcome. Investigators concluded, “all major adverse pregnancy outcomes should now be recognized as long-term independent risk factors for CKD.”