Newborn Weight Loss, Weight Gain and Jaundice: What's Normal

Why newborns lose weight

• Babies are born carrying extra fluid, which they lose in the first days.
• They pass meconium, the dark first stools.
• Early feeds are small: colostrum comes in teaspoons, and milk volume rises once milk comes in around days 2-5.

How the loss is measured

• As a percent of birth weight. Example: a baby born at 7 lb 8 oz (120 oz, about 3,400 g) who loses 7% has lost about 8.4 oz (about 240 g) and weighs about 7 lb 0 oz (about 3,160 g). A 10% loss would be 12 oz (340 g), down to 6 lb 12 oz.
• Losing some weight is expected: often 5-7%, and up to about 7-10% in some breastfed babies. Over 7% prompts a closer look at feeding; 10% or more needs prompt evaluation and a feeding plan.
• The low point is usually around days 3-4. Most babies are back to birth weight by 10-14 days and nearly all by 3 weeks.

If the loss is higher than expected

The pediatrician will usually: - Watch a feed and set a plan: often 8-12 feeds a day, waking the baby if about 3 hours have passed. - Recheck weight every day or two until it is clearly climbing. - Bring in a lactation consultant (IBCLC) to check latch and milk transfer. - Add supplementation if needed: expressed milk first, then donor milk or formula. Supplementing for a while does not mean breastfeeding has failed.

After birth weight is back

• Typical gain in the first months is roughly 5-7 oz (150-200 g) a week, slowing after 3-4 months and again in the second half of the first year.
• Many babies double birth weight by about 4-5 months and triple it by about 12 months.

Signs feeding is going well between visits

• Diapers: at least 6 wet a day from day 5, and stools that turn from black to green to yellow by about day 5 (see the diapers guide).
• Audible swallowing during feeds, and a baby who seems content after most feeds.

Growth charts and percentiles

• US pediatricians use the WHO growth charts for children under 2, then CDC charts.
• A percentile compares your baby with others of the same age and sex; the 15th is as healthy as the 85th. Following a steady curve matters more than the number; a fall across two or more major lines is what prompts a closer look.

Jaundice (yellow skin)

• Most newborns turn a little yellow. It usually starts on days 2-4, peaks around days 3-5 and fades within 1-2 weeks in formula-fed babies. In breastfed babies it can linger for weeks; that's often harmless, but past 3 weeks it still needs a check.
• Every baby gets a bilirubin check (skin meter or blood test) before leaving the hospital, and a follow-up visit within a few days; the timing depends on the level and risk factors.
• Check in daylight: press gently on the forehead or chest and look at the skin as it lifts. Jaundice moves from the face down to the chest, belly and legs. Eyeballing it is unreliable, especially on darker skin, so if you're unsure, ask for a bilirubin check.
• Feeding often helps the baby clear bilirubin through stools. Don't give water or sugar water, and don't put the baby in sunlight to treat it; phototherapy is the treatment when levels are high.

When to check in

Mention it to the pediatrician if jaundice is still there after 2 weeks in a formula-fed baby or 3 weeks in a breastfed baby.

Call the pediatrician the same day if: - There's any yellow color in the first 24 hours, yellow spreading to the belly or legs, yellow whites of the eyes, or yellow that gets deeper. - The baby is very sleepy, hard to wake or feeding poorly, or still losing weight after day 5. - Diapers fall below the expected counts, or stools are pale, white or clay-colored. - A baby under 3 months has a temperature of 100.4°F (38°C) or higher. Call 911 if the baby can't be woken or is limp.