Being told your newborn has lost weight is one of the things that frightens parents most, and it is one I reassure families about often. Some early weight loss is expected and normal. What matters is how much, and how quickly your baby gets back on track. Here is what the numbers mean.

Why newborns lose weight at first

Babies are born with extra fluid, and in the first few days they pass urine and meconium, the first dark poo, while your milk supply is still coming in. So a small dip in weight in the first few days is normal, and then babies start to regain.

When your baby is weighed

Your baby is weighed at birth, and then again in the first few days. Most NHS trusts weigh on day 5, and some on day 3, to check how feeding is going. Your midwife carries out these weights and keeps an eye on the trend. Most babies are back to their birth weight by around two to three weeks.

How much is normal

Weight is measured against birth weight:

  • A loss of up to about 10% is considered within the normal range.
  • A loss of around 8% to 12% will usually prompt a feeding plan, which is extra support to get feeding and weight moving in the right direction.
  • A loss of more than 12% needs prompt medical review, usually a trip to A&E to be seen by a paediatrician.

Your midwife does the weighing, so if your baby's loss reaches one of these points, she will be the one to tell you and to put a plan in place. This is deliberate, so that parents are not left counting grams and chasing weights themselves. You do not need to work the numbers out on your own.

What helps a baby regain weight

The answer is nearly always more effective, more frequent milk transfer. Depending on what a feeding assessment shows, a plan might include:

  • Improving latch and positioning so your baby removes milk well. You can read more in Latch and nipple pain.
  • Feeding more often, and offering both breasts.
  • Waking a sleepy baby for feeds.
  • Breast compressions during feeds to keep milk flowing.
  • Expressing to protect or boost supply, and topping up if genuinely needed, ideally with your own milk first.

Any top-ups should be part of a plan that also protects your supply, so you can reduce them again as feeding improves. You can read more about supply in Is my milk supply low.

When to get help

Your midwife and health visitor monitor your baby's weight and will guide you if there is a concern. Between visits, it is the feeding, and how your baby seems, that you can watch.

Contact your midwife or health visitor if:

  • Your baby has fewer wet or dirty nappies than expected.
  • Your baby is sleepier than usual, or harder to wake for feeds.
  • Feeding is painful, or feels like it is not working.

Call 999 or take your baby straight to A&E if your baby:

  • Is floppy or unresponsive
  • Will not wake for feeds
  • Is having trouble breathing, or their lips, tongue or gums look blue or grey
  • Has a sunken fontanelle
  • Is visibly jaundiced and unwell with it, for example floppy, hard to wake or not feeding. Yellowing shows most clearly in the whites of the eyes, the gums, and the palms and soles
  • Has dark urine or pale, chalky stools

How a consultation helps

Weight worries are one of the most common reasons families call me, and they are often very fixable. If your baby has lost weight, I look at the full feeding picture, watching a whole feed, checking the latch and how well your baby is transferring milk, and weighing them on my own scales. Where the hospital or your midwife has already set a feeding plan, I review it and carry it forward in the community, adjusting it as feeding improves so you are supported the whole way, not left to manage it alone.