Two distinct growth patterns of preterm infants from birth to 18 months of corrected gestational age: a retrospective cohort study.

BACKGROUND

How maternal and infant risk factors are related to long-term multidimensional growth trajectories in preterm infants remains unclear. This study aimed to identify different growth trajectories in preterm infants by integrating weight, length, and head circumference measurements, and to investigate associated risk factors.

METHODS

In this retrospective cohort study, 68 preterm infants [<37 weeks gestational age (GA)] were followed from birth up to 18 months of corrected GA. Growth indicators were Z scores of weight, length, and head circumference [i.e., weight-for-age (WAZ), length-for-age (LAZ), head circumference-for-age (HCAZ), and weight-for-length (WLZ)] according to World Health Organization standards. Group-based multi-trajectory modeling was applied to identify potential trajectory patterns. Poisson regression models with robust variance estimators were used to assess the associations between baseline characteristics and the identified trajectories.

RESULTS

Two distinct growth trajectories were identified. Approximately 40% of infants exhibited lower growth pattern, with mean WAZ, LAZ, HCAZ, and WLZ around -0.5, -1.0, -1.0, and 0.0, respectively. The remaining 60% showed higher growth pattern, with all Z-scores approaching +1.0. Multivariable analyses revealed that small for gestational age (SGA) [relative risk (RR) =2.23, 95% confidence interval (CI): 1.40-3.57], hypertensive disorders of pregnancy (HDOP) (RR =1.84, 95% CI: 1.01-3.36), and twin pregnancy (RR =1.74, 95% CI: 1.00-3.03) were significant risk factors for lower growth pattern.

CONCLUSIONS

A substantial proportion of preterm infants are at risk of lower growth pattern after discharge. Those with low birthweight, exposure to mother HDOP, or from twin pregnancy need more intensive follow-up and personalized nutritional interventions.