Newborn Weight: What’s Normal, When to Worry, and What It Means for Your Baby

When your baby is born, their newborn weight, the measured mass of a baby at birth, typically ranging from 5.5 to 8.8 pounds in the UK. Also known as birth weight, it’s one of the first things you’ll hear—and one of the most nerve-wracking. Most babies lose a bit of weight in the first few days after birth. That’s normal. They’re adjusting, getting used to feeding, and their bodies are shifting from the womb’s constant supply to life outside. By day five to seven, most babies start gaining again. If your baby’s weight doesn’t bounce back by two weeks, your health visitor will want to check in. But don’t panic—many healthy babies take a little longer.

Average newborn weight, the typical range of weight for babies born in the UK, is around 7.5 pounds. Also known as mean birth weight, it’s not a target—it’s a reference point. Some babies are born smaller, some larger. A low birth weight, under 5.5 pounds, can happen for many reasons, including prematurity or genetics, and doesn’t always mean there’s a problem. On the flip side, a 10-pound baby, a newborn weighing over 10 pounds, is larger than average but still within the normal range. What matters isn’t the number on the scale—it’s the trend. Is your baby feeding well? Are they wetting enough nappies? Are they alert and responsive? These are better signs than any single weight reading.

Weight gain in the first month is your baby’s biggest clue that they’re thriving. Most babies gain about half an ounce to an ounce a day after the first week. That’s roughly 1 to 2 pounds in the first month. If your baby is breastfeeding, their weight gain might be slower at first—this is common. Formula-fed babies often gain faster, but both are fine if they’re following their own curve. Your health visitor will plot your baby’s weight on a growth chart. It’s not about hitting the middle line—it’s about staying on their own line. A drop from the 50th to the 25th percentile? That’s normal if it’s consistent. A sudden drop from the 75th to the 10th? That’s when you call your midwife.

Don’t compare your baby to others. One baby might be long and lean, another short and chunky. Both can be perfectly healthy. What you’re really watching for is progress, not perfection. If your baby is latching well, seems satisfied after feeds, and has six to eight wet nappies a day, they’re likely getting enough. If you’re worried about their weight, keep a feeding log. Note how often they feed, how long they nurse, and how they act after. That’s more helpful than a scale reading.

The posts below cover real-life questions from UK parents: how to tell if your baby is gaining enough, what to do if they’re not, how newborn weight affects car seat choices, what clothes fit a larger or smaller baby, and even what hospital blankets are given to babies of different sizes. You’ll find practical advice on feeding, gear, and when to speak up—no fluff, no fear-mongering, just what works.