Low Birthweight Increases Risk for Developmental Concerns in Full-Term Infants

Infants born below the 25th percentile for birthweight are at a higher risk for developmental concerns compared with those born between the 25th and 74th centile.

Infants born at 37 weeks of gestation with a birthweight below the 25th percentile demonstrate an increased risk for developmental concerns compared with infants who are not considered small for gestational age (between the 3rd and 10th percentiles), according to study findings published in Public Library of Science’s Medicine.

Researchers in the United Kingdom wondered if low birthweight percentiles in infants carried to full-term affected their childhood development.

To answer this question, they conducted a population-based cohort study of 686,284 infants born from 37 weeks’ gestation. They linked information on pregnancy and delivery from the Scottish Morbidity Records from 2003 to 2015 with developmental assessments of the children between ages 2 and 3.5 years.

Child development assessments included Ages and Stages Questionnaires-3 (ASQ-3), Ages and Stages Questionnaire: Social and Emotional-2 (ASQ: SE-2), and the Modified Checklist for Autism in Toddlers (M-CHAT). These outcome measures assessed fine and gross motor control, communication, and social development in these children.

The researchers observed that infants below the 25th percentile in birthweight after 37 weeks’ gestation showed an increased risk for developmental concerns compared with infants with a birthweight scored between the 25th and 75th percentiles.

Infants with a birthweight between the 10th and 24th percentiles had an increased risk for developmental concerns (relative risk [RR], 1.07; 95% CI, 1.03-1.12; P <.001). Similarly, infants with a birthweight between the 3rd and 9th percentile (RR, 1.18; 95% CI, 1.12-1.25; P <.001) and those lower than the 3rd percentile (RR, 1.37; 95% CI, 1.24-1.50, P <.001) also had an increased risk.

In contrast, infants whose larger birthweight reached the 75th to 89th percentiles (P =.56), 90th to 96th percentiles (P =.86), and the 97th percentile or above (P =.27), did not demonstrate significantly increased risk for developmental concerns.

“Mild to moderate [small for gestational age] is an unrecognized, potentially important contributor to the prevalence of developmental concerns,” the researchers stated. “Closer surveillance, appropriate parental counselling, and increased support during childhood may reduce the risks associated with lower birthweight centiles,” they advised.

Study limitations include the use of the ASQ as a screening tool, the subjective design of developmental assessments, and lack of control for early childhood illness and variables in upbringing that may have also influenced the results.

Disclosures: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.


Adanikin A, Lawlor DA, Pell JP, Nelson SM, Smith GCS, Iliodromiti S. Association of birthweight centiles and early childhood development of singleton infants born from 37 weeks of gestation in Scotland: a population-based cohort study. PLoS Med. Published online October 11, 2022. doi:10.1371/journal.pmed.1004108