Why do babies lose weight in the first few days of life?

Newborn baby on the balance

It is normal for a baby to lose weight by around the third to fifth day post birth. This weight loss is linked to the natural loss of excess fluid from outside the baby’s body cells; this is part of the baby’s adaptation to life outside the womb.

The amount of weight lost tends to be around 10% of the baby’s birth weight in the first week. From day five post birth onwards, the baby’s average weight gain is approximately 30g per day until the baby is around six months of age. However, it may also be that the baby does not regain their birth weight until 10-14 days post birth.

Babies who are breastfed do not gain weight as quickly as those babies who are formula milk/bottle fed. However, all babies are individual and the above rates provide an average, so it is important that new parents do not become preoccupied or over anxious about their baby’s weight gain.

Davanzo R, Cannioto Z, Ronfani L et al (2013). Breastfeeding and neonatal weight loss in healthy term infants. Journal of Human Lactation 29(1):45-53.

Macdonald PD, Ross SR, Grant L et al (2003). Neonatal weight loss in breast and formula fed infants. Archives of Disease in Childhood: Fetal and Neonatal Edition 88(6):F472-F476.

Mulder PJ, Johnson TS, Baker LC (2010). Excessive Weight Loss in Breastfed Infants During the Postpartum Hospitalization. JOGNN: Journal of Obstetric, Gynecologic and Neonatal Nursing 39(1):15-26.

Speidel B, Fleming P, Henderson J et al (1998). A neonatal vade-mecum. London: Arnold. 50.

Wright CM, Parkinson KN (2004). Postnatal weight loss in term infants: what is “normal” and do growth charts allow for it? Archives of Disease in Childhood: Fetal and Neonatal Edition 89(3):F254-F257.

2017-05-26T16:29:33+00:00