The skinny on a newborn’s weight: Getting your facts straight before overreacting

Worried your baby is losing weight too soon after birth? Before you start worrying about him or her drinking too little or being sick, here are some facts about newborns’ weights.

When babies are “in utero,” it’s practically like they’re living underwater. At birth, they enter extra-uterine life, causing them to lose a certain amount of water through breathing, sweating, evaporation, perspiration and urination.

Babies under stress (e.g. separation, sensory deprivation, inadequate hygiene, long periods between feedings, etc.) lose more water at a quicker pace. When this happens, they also lose heat and energy, which means their weight could also go down too much or too quickly. 

Typical birth weight

Normally, birth weight = the baby’s weight + his or her meconium level + the excess water that he or she will expel. Thus, it’s important to understand that your baby might lose weight during the first few days without necessarily being in any kind of danger.

How does one go about reducing stress, water and weight loss?

  • Skin-to-skin contact
  • Being held
  • Closeness
  • Proper hygiene
  • Wearing a bonnet
  • Avoiding dry air
  • Avoiding drafts
  • Breastfeeding when he or she wakes up
Further context

Most full-term babies (born between 37–42 weeks) weigh somewhere between 5.5–9.5 pounds (2,500–4,300 grams).

During the first few days after birth, your baby can lose up to 10% of his or her weight, which is normal. In addition to expelling meconium and losing water, he or she will also only be drinking a small quantity of milk at a time. If your baby was born at term and healthy, he or she will get back to birth weight within 2–3 weeks.

All babies have their own growth rates and develop in spurts. Premature babies, however, generally have slower growth rates, but will catch up with those born at term by five years old. Also remember that breastfed babies and those fed with formula will not develop in the same way.

Here are some reference points to help you check if your baby is gaining the right amount weight:

  • 1 kg (2.2 lb.) per month from 0–3 months
  • 500 g (1 lb.) per month from 4–6 months
  • 250 g (1/2 lb.) per month from 7–12 months
  • Your baby will then gain 4–5 lb. (1.8–2.3 kg) during his or her first and second years of life. Most babies (premature notwithstanding) double their birth weight at four or five months old, and triple it by their first birthday.

You can find these weight references in From Tiny Tot to Toddler, a little handbook issued by hospitals and doctors in Quebec. It’s also worth noting that scales for weighing newborns are available at many pharmacies.

Weight is an important way of ensuring that your baby is healthy, but there are other signs, such as urine, stool and wakefulness. If you’re anxious about your baby’s weight, consult a nurse, but don’t declare that the sky is falling just yet because weight is not the only important factor to consider.

Karine Bergeron

Karine Bergeron is a doula who studied nursing and is currently completing additional training in prenatal care. As mother to little Laurence, volunteer for L’entraide maternelle, breastfeeding godmother and prenatal class teacher, it’s with joy that she dispenses her wisdom for Bergeron is passionate about prenatal care and ready to share all her knowledge to help you enjoy life’s greatest gift: becoming parents. To find out more or ask questions, go to and look for her in the “Équipe” section.

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