Weight Change Nomograms for the First Month After Birth

Area of Science:

• Neonatal Health
• Pediatric Growth Monitoring

Background:

• Clinicians anticipate newborns regaining birth weight within 10-14 days.
• Limited research exists on the typical trajectory of newborn weight changes post-birth.

Purpose of the Study:

• To analyze the distribution of newborn weight loss and regain in the first month.
• To determine the proportion of infants not surpassing birth weight by 14 and 21 days.
• To investigate if delivery mode influences these weight change patterns.

Main Methods:

• Utilized electronic health records for 143,889 singleton neonates (≥36 weeks gestation).
• Extracted daily weights during hospitalization and outpatient visits within the first month.
• Employed quantile regression for repeated measures to model weight change percentiles by delivery mode.

Main Results:

• 50% of vaginally-born infants regained birth weight by 9 days; 50% of cesarean-born infants did so by 10 days.
• 14% of vaginally-born infants and 24% of cesarean-born infants had not regained birth weight by 14 days.
• 5% of vaginally-born infants and 8% of cesarean-born infants had not regained birth weight by 21 days.

Conclusions:

• Newborns commonly remain below birth weight at 10-14 days postpartum.
• Infants delivered via cesarean section demonstrated a higher incidence of delayed birth weight regain at all measured time points up to one month.