Why do Babies Lose Weight in the First 2 Weeks

You just had a baby. Congratulations! They weigh him and he weighs 7lbs and 13oz. You’re overjoyed. You breastfeed him and he seems to latch on. Maybe instead you formula feed him and he takes a couple of ounces. Hooray! But wait, they weigh him again a couple of days later as you leave the hospital, and now he weighs 7lbs and 6oz. He is shrinking! Infant weight loss, is that a thing?

Infant weight loss is a thing!

First, most babies will lose weight in the first one to two weeks of life. This happens because babies are born with some extra water weight. Plus, they are also usually sleepy in the beginning. Feeding is hard work!

Do both breastfed and formula fed babies lose weight?

Most do. However, studies have shown that breastfed babies tend to lose more weight in the beginning than formula fed babies. This likely reflects the fact that it might take a couple of days for a mother’s milk to fully come in.

When will they gain it back?

Most babies gain it back by week 1 of life, sometimes breastfed babies take about 2 weeks to get back to their birth weight.

How much weight loss is too much weight loss?

Typically, we start to worry if a baby has lost more than 10% of their body weight in the first two weeks of their life. For example, if your baby was born at 7lbs and 13oz and they drop their weight to 7 lbs, they have lost about 10%.  Your pediatrician will want to monitor you a bit more closely to figure out if they are just not eating enough or if there is another reason why their bodies might be using up extra calories. This tool helps you figure out if you are getting close to that 10%, or if your baby is losing weight too fast, and should be worried about your child’s weight.

What goes down, must go up

I know, that is not really the saying but roll with it with me. Infant weight loss in the first days will usually reach a low point and then start going back up! How fast you ask? A general rule of thumb is that babies gain about 1 ounce a day once they start gaining weight.

What can happen if my baby is losing too much weight or not gaining enough?

The main things we worry about when babies are losing too much weight is that they could be getting dehydrated or they could be getting jaundiced (turning a little yellow). If you see this contact your pediatrician.

What else can I do?

If you are formula feeding and infant weight loss is too much your pediatrician may suggest you feed more frequently, especially if your baby is really sleepy. If you are breastfeeding, they may suggest you don’t let them go more than 2-3 hours without feeding. They might also mention supplementing with formula or “triple feeding” meaning you express or pump some breastmilk after every feed and offer that milk through a bottle to your baby as well. 

Want more help?

Remember, you are not alone! If you are breastfeeding, a lactation consultant is a helpful person to have on your team. We have several as Fooblie coaches! Connect with them to get some personalized attention to help troubleshoot feeding. When in doubt, reach out to your pediatrician. 

You’ve got this!