Associations of prematurity and low birth weight with blood pressure and kidney function in middle-aged participants of the Brazilian Longitudinal Study of Adult Health: ELSA-Brasil.

Background: An adverse intrauterine environment reflected by low birth weight (LBW) and prematurity may induce fetal programming that favors kidney dysfunction in adulthood. We examined the association of LBW and prematurity with blood pressure (BP) and kidney function markers in non-diabetic, middle-aged adults without kidney disease from the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil).

Methods: A cross-sectional analysis of 768 subjects aged 35-54 years was conducted. Comparisons were performed according to self-reported birth weight: LBW (< 2.5 kg) or normal birth weight (2.5-4.0 kg). Associations of LBW and prematurity with BP levels and kidney function markers "(estimated glomerular filtration rate [eGFR], albumin-creatinine ratio [ACR] and serum cystatin-C) were tested by multiple linear regression using adjustments based on Directed Acyclic Graphs. Propensity score matching was applied to control imbalances.

Results: Mean age of participants was 45.5 ± 4.6 years and 56.8% were female; 64 (8.3%) participants reported LBW and 39 (5.0%) prematurity. The LBW group had higher systolic (p = 0.015) and diastolic BP (p = 0.014) and ACR values (p = 0.031) and lower eGFR (p = 0.015) than the normal birth weight group, but no group difference for cystatin-C was found. The preterm group had higher mean levels of systolic and diastolic BP, but no difference in kidney function markers was evident. In a regression model adjusted for sex, skin color and family history of hypertension, both systolic and diastolic BP levels were associated with LBW, but this association disappeared after adding for prematurity, which remained associated with BP (p = 0.017). Having applied a propensity score matching, LBW was associated with ACR values (p = 0.003), but not with eGFR or BP levels.

Conclusion: The study findings of independent associations of prematurity with higher BP levels, and of LBW with markers of kidney function in adulthood, support that early life events may predict risk for hypertension and kidney dysfunction in adulthood. The study design precluded the inferring of causality, and prospective studies are needed to further investigate this hypothesis.