Most newborns  lose weight in the first few days after birth for a number of reasons. Newborn weight loss  of less than 10% of birth weight is normal. However it becomes concerning when the baby loses more weight. Excessive  weight loss within the few days of life in newborns can be due to reasons such as breastfeeding problems or  physical illness.

What is considered normal newborn weight loss

Before birth,  babies spend most of their time in the amniotic fluid.  At birth they seem somewhat waterlogged so they need to lose the extra fluid and this results in weight loss. It may also take babies some time to master  breast or bottle feeding and this can also result in some weight loss. This weight  is loss is temporary. About 95% of  babies who are bottle fed  regain their birth weight by 14.5 days, and 95 percent of breastfed babies by 18.7 days.

What is considered abnormal weight loss in newborns ?

Extensive weight loss is not normal and is usually due to feeding problems. It is more common in breastfed babies because it takes about 3 to 5 days for the milk to come in. These babies also need to exert  more effort to get milk from the  breast. Rarely this type of weight loss may be the result of a medical condition such as metabolic disease, heart, lung  or kidney problem or an infection.

Excessive weight loss in a newborn usually reflects reduced fluid intake which can result in dehydration. Dehydration can increase your baby’s risk of newborn jaundice. It can also result in high sodium levels in the blood which can cause slow heart rate or periods of apnea.

When to call your doctor

Seek emergency medical care if your newborn has a fever , is not feeding or seems lethargic. You also need to call your doctor if you newborn exhibits signs of dehydration.