Why does a baby's weight decrease after birth?
Oct 13, 2022
Source: Cainiu Health
Dr. Xie Zixing
Introduction
After birth, a baby's weight may decrease due to fluid loss, along with the passage of feces and urine and limited milk intake. This is considered a normal physiological weight loss period. However, weight loss could also result from inadequate milk intake leading to malnutrition. Additionally, poor digestion or infectious diseases causing diarrhea may also lead to weight loss.
Weight loss in newborns is usually due to physiological weight loss, but it may also be caused by malnutrition, diarrhea, or other reasons.
1. Physiological Weight Loss
Prior to birth, newborns are immersed in amniotic fluid within the uterus and therefore typically have a high body water content. After birth, fluid loss occurs along with the passage of meconium and urine. Additionally, milk intake is relatively low during the initial days, leading to a temporary drop in body weight—this is known as physiological weight loss. The decrease is most noticeable around 3–4 days after birth, typically amounting to 3%–9% of the birth weight, and the baby usually regains their birth weight by 7–10 days of age.
2. Malnutrition
Weight loss in newborns may also result from inadequate milk intake leading to malnutrition.
3. Diarrhea
If a newborn experiences indigestion or develops an infectious disease causing diarrhea, this may also lead to weight loss.
If a newborn shows weight loss after birth, it is recommended to visit a hospital for appropriate evaluations to identify the underlying cause and rule out any potential illnesses.
