Trajectory Patterns of Weight and Length in Children: From Birth Until 2-Years of Age.

Objective: The aim was to identify trajectory patterns of weight and length in children from birth until two years of life and establish associations with maternal and child characteristics.

Methods: A mixed-cohort study was conducted in public health services in Colombo-PR, Brazil, between 2018 and 2022. Pregnancy information was gathered through anthropometric data collection and questionnaires. Birth data were extracted from birth record forms, while weight and length data in the first two years of life were obtained from physical and electronic health service records. Weight and length trajectory patterns were identified using a group-based trajectory model. The definition of the number of trajectory patterns to be selected considered the model fit to the type of variable, its practical utility, as well as the probabilities of group membership.

Results: Two trajectory patterns of weight and length were identified among the children. The majority exhibited a pattern of weight (67.8%, n = 382) and length (90.9%, n = 472) considered high and stable, with a tendency to decelerate from one and a half years of age. The probability of belonging to the lower weight gain group was associated with female sex (41.5%, p < 0.001), smoking during pregnancy (48.7%, p = 0.008), prematurity (65.0%, p = 0.001), cesarean delivery (36.4%, p = 0.009), small for gestational age (69.0%, p < 0.001), and twinning (69.2%, p = 0.002). Similarly, the probability of belonging to the lower length gain group was associated with female sex (11.7%, p < 0.001), smoking during pregnancy (20.6%, p = 0.003), cesarean delivery (10.1%, p = 0.048), born small for gestational age (46.4%, p < 0.001), and twinning (46.1%, p < 0.001).

Conclusion: Conditions during pregnancy and childbirth can impact growth patterns in the first two years of life.