The impact of environmental exposures during pregnancy on newborn health has garnered increasing attention. Prior research has suggested that a reduced number of nephrons at birth may heighten the risk of hypertension and other health issues, emphasizing the critical role of optimal kidney function in maintaining overall body homeostasis.
Recent findings have highlighted the challenges of assessing kidney function in neonates. Cystatin C, a protein filtered by the kidneys and produced by nucleated cells, has emerged as a key marker for evaluating glomerular filtration in newborns. Unlike other markers, cystatin C levels are not influenced by muscle mass or inflammation, making it a valuable tool for assessing early kidney function.
Ambient air pollution, particularly particulate matter with a diameter of less than 2.5 micrometers (PM2.5) and black carbon (BC), has been linked to a range of health issues including cardiovascular, respiratory, and kidney problems. Maternal exposure to these pollutants has been associated with higher blood pressure and reduced birth weight, potentially affecting kidney development in infants. While studies have documented the effects of air pollution on cystatin C levels and glomerular filtration in adults, research on its impact on newborns remains limited.
Study Overview
This study aimed to investigate whether maternal exposure to BC and PM2.5 affects cystatin C levels in the cord blood of newborns. Data were collected from 1,484 healthy mother-newborn pairs participating in the ENVIRONAGE birth cohort in Belgium, covering singleton pregnancies between 2010 and 2020.
Exclusion criteria included missing cord blood samples or incomplete data. Exposure levels to BC and PM2.5 were estimated using satellite land cover data and monitoring station records, with daily exposure averaged for the entire pregnancy and across trimesters. Cord blood samples, collected within 10 minutes of delivery, were analyzed for cystatin C levels using an accredited immune turbidimetry assay.
Statistical analyses employed multiple linear regression, distributed lag models, and logistic regression, adjusting for covariates such as age, education, smoking habits, alcohol consumption, and ethnicity.
Results
The study found that the average birth weight of newborns was 3,417.52 grams, with 49.6% being female and an average gestational age of 39.2 weeks. Cord blood cystatin C levels averaged 2.16 mg/L. The mean exposure to BC and PM2.5 during pregnancy was 1.18 μg/m³ and 12.65 μg/m³, respectively, with exposure levels remaining consistent across trimesters.
Significant associations were observed between BC exposure and elevated cystatin C levels. A 0.5 μg/m³ increase in BC exposure was linked to a 0.04 mg/L rise in cystatin C (p<0.01). For PM2.5, a 5 μg/m³ increase correlated with a 0.07 mg/L increase in cystatin C (p<0.01).
The study found that BC exposure in the first trimester was associated with elevated cystatin C levels, while PM2.5 showed no such association in this period. Sensitivity analyses confirmed that these results were robust across various adjustments. Notably, the third trimester (post-week 27) emerged as a critical period for exposure impacts.
Increased exposure to PM2.5 and BC throughout pregnancy, especially in the third trimester, was associated with a higher risk of elevated cord blood cystatin C levels. Specifically, a 0.5 μg/m³ increase in BC exposure was linked to a 37% higher risk, and a 5 μg/m³ increase in PM2.5 was associated with an 80% higher risk.
Conclusion
The study concludes that exposure to PM2.5 and BC during pregnancy, particularly in the third trimester, is significantly associated with elevated cystatin C levels in newborns, indicating potential adverse effects on kidney function from birth. These findings underscore the importance of monitoring and mitigating early-life exposure to particulate air pollution to improve long-term kidney health. Further research is needed to explore these associations and inform public health policies aimed at enhancing newborn health outcomes.
