Contributor: Sean Fox, MD Educational Pearls: Newborns may lose up to 10% of their birth weight in the first week of life Weight loss is greatest in exclusively breastfed infants Should regain birth weight by age 2 weeks Newborns should gain an average of 30g (1 oz) per day in the first 3 months of life Some will gain more and some will gain less Infants double their birth weight by 6 months of life and triple their weight by 12 months A 1-year-old should weigh on average 10 kg (22 lbs) A 3-year-old should weigh on average 15 kg (33 lbs) 2-year-olds are between 10-15 kg on average Weight assessment can help determine causes of forceful vomiting Not all “projectile” vomiting is due to pyloric stenosis Some infants may experience vigorous vomiting from overfeeding Weight estimates can also provide information for quick decisions on medical management for children coming via EMS  Helps to prepare medications and dosages based on predicted average weight References Crossland DS, Richmond S, Hudson M, Smith K, Abu-Harb M. Weight change in the term baby in the first 2 weeks of life. Acta Paediatr. 2008;97(4):425-429. doi:10.1111/j.1651-2227.2008.00685.x Grummer-Strawn LM, Reinold C, Krebs NF; Centers for Disease Control and Prevention (CDC). Use of World Health Organization and CDC growth charts for children aged 0-59 months in the United States [published correction appears in MMWR Recomm Rep. 2010 Sep 17;59(36):1184]. MMWR Recomm Rep. 2010;59(RR-9):1-15. Macdonald PD, Ross SR, Grant L, Young D. Neonatal weight loss in breast and formula fed infants. Arch Dis Child Fetal Neonatal Ed. 2003;88(6):F472-F476. doi:10.1136/fn.88.6.f472 Paul IM, Schaefer EW, Miller JR, et al. Weight Change Nomograms for the First Month After Birth. Pediatrics. 2016;138(6):e20162625. doi:10.1542/peds.2016-2625 Summarized & Edited by Jorge Chalit, OMS3 Special thanks to the Carolinas Medical Center for their contribution to this episode Donate: https://emergencymedicalminute.org/donate/