Paired Maternal and Neonatal Telomere Length at Birth: An Exploratory Study of Mother–Infant Dyads

Background/Objectives: Telomere length varies between individuals from birth, but the relationship between maternal and neonatal measurements within the same family remains incompletely understood. This study examined paired telomere length at delivery and explored associations with maternal and neonatal clinical characteristics. Methods: In this single-center observational study, maternal peripheral blood and neonatal umbilical cord blood were collected from 150 mother–infant pairs. Telomere length was measured by quantitative polymerase chain reaction. Paired measurements were compared using the Wilcoxon signed-rank test, and their association was assessed using Spearman’s correlation. Exploratory clinical associations were examined with unadjusted analyses and multivariable linear regression. Results: The median assay-derived estimate of total telomere length (TTL) was 1.29 Mb per diploid cell (IQR, 0.98–1.53) in neonatal samples and 0.94 Mb per diploid cell (IQR, 0.77–1.10) in maternal samples. Neonatal TTL estimates exceeded maternal estimates in 125 of 150 pairs (83.3%). The median within-pair difference was 0.35 Mb per diploid cell (IQR, 0.08–0.61; 95% CI, 0.27–0.43; p < 0.001). Maternal and neonatal TTL estimates were positively correlated (Spearman’s ρ = 0.479; 95% CI, 0.35–0.59; p < 0.001). In an exploratory adjusted model, maternal TTL was positively associated with neonatal TTL (β = 0.662 Mb per diploid cell per 1 Mb increase in maternal TTL; 95% CI, 0.453–0.871). Maternal age showed an inverse association with neonatal TTL (β = −0.013 Mb per diploid cell per year; 95% CI, −0.022 to −0.003), while female newborn sex showed a positive association (β = 0.128 Mb per diploid cell; 95% CI, 0.019–0.238). Prepregnancy BMI, gestational age, and active maternal smoking showed no clear adjusted associations. These clinical findings are exploratory: only the unadjusted maternal-age association remained statistically significant after Holm–Bonferroni correction across the 16 clinical tests; the sex-related associations did not. Conclusions: Maternal and neonatal telomere lengths were related at birth, although neonatal values varied substantially among pairs with similar maternal values. Larger studies are needed to confirm the secondary clinical associations and assess their potential clinical relevance.