Heart rate variability after hospital discharge in perinatal risk populations: a systematic review and meta-analysis.

Abstract

Background: Perinatal risk factors such as preterm birth, intrauterine growth restriction, and low birth weight are linked to elevated cardiovascular and neurodevelopmental risk. Heart rate variability (HRV) is widely used to assess autonomic function in these populations, yet findings remain inconsistent. While autonomic differences during the NICU period are well established, less is known about HRV after hospital discharge across childhood and adulthood.

Methods: PubMed, EMBASE, Web of Science, Scopus, and APA PsycArticles were searched through April 2025, supplemented by ClinicalTrials.gov and reference screening. Peer-reviewed studies comparing HRV between perinatal risk populations and healthy full-term controls after hospital discharge were eligible. We extracted 156 effect sizes from 27 studies.

Results: Overall effects were modest and highly heterogeneous (d = -0.21, p = 0.14; I² =  89.3%). Growth-related conditions (small-for-gestational-age, intrauterine growth restriction) showed the most consistent HRV reductions. Preterm birth and low birth weight showed no significant overall effects but substantial between-study heterogeneity across age groups. Younger samples showed larger group differences than older samples.

Conclusion: Autonomic associations with perinatal risk factors appear condition-specific and age-dependent, although the predominantly cross-sectional design precludes conclusions about within-individual change. Findings underscore the importance of age- and condition-specific assessment and the need for longitudinal follow-up.

Impact: HRV associations with perinatal risk factors are condition-specific and vary across age. Effect sizes were most consistent for growth-related conditions (small-for-gestational-age and intrauterine growth restriction), pronounced in preterm-born infants but smaller and more variable in older groups, and small or non-significant for low and extremely low birth weight samples. This is the first meta-analysis to quantify HRV differences across perinatal risk populations from infancy to adulthood, focusing on the post-discharge period and showing that timing and etiology, rather than parameter choice, drive inconsistencies. The findings guide condition-specific assessment and underscore the need for longitudinal studies separating catch-up from survivor bias.