Long-term outcomes for large babies

Studies show long-term risks for children born small for their gestational age. Early Development Instrument (EDI) research shows these babies are at greater risk for later developmental vulnerability.

Less is known about babies born large for their gestational age.

Research Summary

  • Large for gestational age babies are not at increased risk of childhood mortality or developmental vulnerability.
  • They show a trend towards slightly better school performance.
  • Family factors played a larger role than a child’s size at birth.

What is the research about?

Large for gestational age babies have higher risk of short-term health outcomes. But the longer-term risks are less known.

A University of Sydney study looked at 449,857 babies from New South Wales, Australia between 2001-2006. Babies were categorized into two groups:

  • Large infants (>90th percentile for birth weight, gestational age, and sex): 49,439
  • Regular sized infants (10th–90th percentile for birth weight, gestational age, and sex): 400,418

The study’s goal was to see the long-term health, development, and educational outcomes of large babies.

These outcomes were measured by:


  • Mortality
  • Number of hospitalizations


  • Early Development Instrument (EDI) vulnerability

Educational outcomes

  • Standardized reading and numeracy scores at ages 3, 5, 7 and 9

This study also evaluated some neonatal outcomes including:

To find out the role of family factors, researchers took into account:

  • Mother’s age
  • Mother’s obesity status
  • Country of Birth
  • Socioeconomic Status (SES)
  • Smoking during pregnancy
  • Mother’s Diabetes status
  • Parents’ Education
  • English as a Second Language

What did the researchers find?

Large for gestational age babies were more likely to have mothers who were:

  • older
  • morbidly obese
  • born in Australia
  • living in rural areas
  • low SES
  • had diabetes
  • non-smokers during pregnancy
  • had given birth two or more times

Large babies were also at increased risk of:

  • caesarean section
  • lower Apgar score at 5 minutes
  • severe neonatal morbidity
  • brachial plexus injury
  • other birth trauma

Despite these risks, large babies had lower rates of later developmental vulnerability. They also were more likely to have high scores in reading and numeracy.

However, family characteristics were more associated with higher reading scores than size at birth, including:

  • being a first child
  • higher maternal age
  • higher parental education

What does this research mean?

Although there are concerns for large for gestational age babies immediately following birth, these did not translate into negative long-term health or educational outcomes. And although there was some evidence to show large babies have better health and educational outcomes than their average size peers, family factors play a larger role.