Baby Weight Loss – what is happening?

My baby is losing weight

My baby is losing weight

Baby Weight Loss

You go for a wellness check, anxious to see how your little one is progressing, and your doctor appears concerned. Your baby has lost weight. Instantly, you begin to worry: What’s going on? Why has my baby lost weight? Am I a bad parent? Let me tell you – baby weight loss is more common than you think. There are a number of reasons for your baby to have lost weight, but keep in mind that is long as your little one has not drastically dropped in percentile there is no need for you to worry. Whatever the cause of your baby’s weight loss, be sure to discuss any of your concerns with your child’s doctor.

Possible Reasons for Baby Weight Loss

Newborn Weight Loss – It is common for a newborn to lose weight (up to 10% of their birth weight) in the first few days of life, but your little one will usually gain the weight back within two weeks. Newborn weight loss is completely normal; your little one has been encapsulated in liquid for nine months and will lose some of that water weight upon entering the world.
How Much/Little Baby Eats – One of the biggest concerns from your doctor will be how much your baby is eating. If you are breastfeeding they will ask how often and for how long your baby eats; if your are feeding formula and/or solids your doctor will ask how often and how much the baby is being fed. Your doctor may suggest more frequent feedings and/or supplementation.

Reflux – Sometimes, a severe case of reflux can be the cause of weight loss because the baby is unable to absorb the nutrients due to reflux. Never fear, I worried about my baby’s spit-up (she projectile vomited regularly), but my doctor assured me that as long as there weren’t more than two or three large spit-ups a day that she was fine. You’d be surprised how much they are still getting! (If your baby is spitting-up frequently, watch for signs of dehydration and contact your doctor with any concerns.)

Diarrhea – Most breastfed babies have loose stool, so moms often have a difficult time determining what is diarrhea. Rest assured, if your little one’s poos are extra runny and lose their grainy appearance, it is probably diarrhea. Diarrhea can be accompanied by mucus, but are most often extremely explosive and runny to the point that they soak into the diaper like urine. Similar to reflux, diarrhea can cause weight loss (primarily from water loss) due to lack of baby’s ability to absorb the food’s nutrients. Other signs of diarrhea include: caved in soft, dark urine, poor overnight diaper, and irritability.

Virus – Unfortunately, the rotavirus (or stomach bug) is the most common culprit of weight loss in young children. Vomiting and diarrhea often accompany a virus and, unfortunately, the only real treatment is to let it run its course. In order to stave off dehydration and weight loss, offer your little one plenty of liquids (breast milk, formula, or pedialyte).

Activity – The upside of baby weight loss could be that your baby has become more active! A crawling baby on the move will often result in some weight loss in your infant.

Again, weight loss in babies is not uncommon, but unless it is excessive there is nothing to be overly concerned about. When in doubt, your baby will let you know if something is wrong. But, if you’re concerned, talk with your doctor who will (no doubt) ask you questions related to what we have shared with you.


  1. I had a reflux baby, and it is challenging to keep those nutrients in their little bodies. It is wise to pay attention to weight, and to express any concerns you are having. Moms may be “new at this,” but often they have a sense if something is off. At the same time, it is comforting to know that there may be very reasonable explanations and a variety of options for addressing any problems.

  2. I remember totally freaking out with my first baby when she lost weight. She was a preemie so every ounce was critical, but I remember a good nurse detailing the same great info you shared in your post. It calmed me down quite a bit!


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