Growth trajectories, health problems and neurodevelopmental outcomes of preterm infants conceived by assisted reproductive technology over 0–24 months of corrected age: a retrospective cohort study

Abstract Background Assisted reproductive technology (ART) is consistently associated with an increased risk of preterm birth and adverse perinatal outcomes. As preterm infants are inherently susceptible to growth impairment and neurodevelopmental deviations, early-life outcomes of ART-conceived preterm infants are clinically relevant to ART safety assessment and patient counselling. However, available evidence on this population remains inconsistent and limited by insufficient perinatal confounder adjustment. This study aimed to evaluate growth, health problems and neurodevelopment up to 24 months of corrected age (CA), and identify factors associated with intergroup growth differences. Methods This retrospective cohort study enrolled 1,353 preterm infants born between 2010 and 2020, including 262 conceived via ART and 1,091 conceived naturally. All outcomes were assessed under a standardised corrected-age framework. Longitudinal growth trajectories were characterised using linear mixed-effects spline models. Multivariable regression and Oaxaca–Blinder decomposition were applied to dissect contributors to growth disparities, and associations between ART procedure parameters and birth weight were further examined. Results ART preterm infants had significantly lower weight, height, head circumference and BMI at birth than naturally conceived peers. These gaps progressively narrowed and lost statistical significance by 24 months of CA. No significant between-group differences were observed in cumulative health problem or neurodevelopmental outcomes. After confounder adjustment, growth differences were mainly associated with perinatal characteristics. Multiple gestation was the main contributor to the birth growth difference, while none of the ART procedure parameters was associated with birth weight. Conclusions ART preterm infants showed early disadvantages that diminished by 24 months of CA, without significant differences in recorded health problems or early neurodevelopment. Growth differences were mainly associated with perinatal characteristics rather than ART procedure parameters, providing reassuring evidence for patient counselling and perinatal management optimisation.