Most full-term newborns weigh 2.5–4.0 kg (5 lb 8 oz–8 lb 13 oz), with an average near 3.3 kg (about 7 lb 4 oz).
Birth weight sits at the center of those first proud stats on a baby card. It also helps doctors judge how a newborn is doing and what kind of care to plan next. So, what counts as “normal,” what shapes that number, and when should parents keep an extra eye on the scale?
This guide gives plain, practical ranges for a term newborn’s weight, explains the common labels you might hear, and shows how weight shifts in the first two weeks. You will also find simple pointers that make day-to-day weighing less stressful.
Average Newborn Baby Weight: Chart And Ranges
Across term births, most newborns land between 2,500 and 4,000 grams. The midpoint hovers near 3,300 grams. Boys tend to weigh a touch more than girls, and small swings by country or region are expected. Clinicians track size using percentiles on standard growth charts to see whether a baby is light, average, or heavy for their exact age in weeks.
| Category | Grams | Pounds & Ounces |
|---|---|---|
| Typical range (37–42 weeks) | 2,500–4,000 g | 5 lb 8 oz–8 lb 13 oz |
| Average term, all sexes | ~3,300 g | ~7 lb 4 oz |
| Female term average | ~3,200 g | ~7 lb 1 oz |
| Male term average | ~3,400 g | ~7 lb 8 oz |
| Low birth weight (LBW) | <2,500 g | <5 lb 8 oz |
| VLBW (under 1,500 g) | <1,500 g | <3 lb 5 oz |
| Often labeled “large” (macrosomia) | ≥4,000–4,500 g* | ≥8 lb 13 oz–9 lb 15 oz* |
*Different clinics use one of these two cutoffs. Percentile-based labels (SGA <10th, LGA >90th) are also common.
For reference charts used in hospitals and clinics, see the WHO weight-for-age standards. These tables list percentiles for boys and girls from birth onward and allow a precise comparison for each week and day.
What Affects A Baby’s Birth Weight
Gestational Age
Every extra week in the late third trimester adds some grams. Early-term babies at 37 weeks often weigh less than those born at 40 or 41 weeks. Preterm babies born before 37 weeks usually weigh less because they had less time to grow in the womb.
Parents’ Build And Genetics
Taller parents tend to have larger babies. Family patterns matter too. A first baby may be lighter than later siblings. Small, healthy parents often have small, healthy newborns who track along lower percentiles yet thrive.
Maternal Health And Habits
Diabetes in pregnancy can raise birth weight. High blood pressure can lower it. Smoking and some substances are linked to lower weight. Food intake and good prenatal care help keep growth on track.
Pregnancy Factors
Boy babies weigh a bit more on average. Twins and triplets are usually smaller because they share space and nutrients. The placenta and cord also play a role in how well nutrients move from parent to baby.
Low Birthweight, Normal, And Large: What The Terms Mean
Low birth weight means less than 2,500 grams at delivery. VLBW means less than 1,500 grams. Doctors also describe babies by percentile for their exact week of gestation: small for gestational age (SGA) is below the 10th percentile and large for gestational age (LGA) is above the 90th percentile. When a baby crosses the high end, teams may note “macrosomia,” a label most often used at 4,000 or 4,500 grams depending on local policy.
Taking The First Weigh-In
Right after birth, the care team dries the baby, places them on a warmed scale, and records the weight to the nearest few grams. The number goes into the medical record and onto that keepsake card. A second check sometimes follows a bit later when the baby is calmer and has passed urine or stool.
Weighing And Tracking In The First Days
It is normal for weight to dip after delivery. Newborns pass meconium, shed extra body water, and adjust to feeding. Many lose 5–7% by day three. Some lose up to about 10%. The pattern is a turn upward by the end of the first week and a return to birth weight by day 10 to 14, especially for breastfed babies. See AAP advice for families for a day-by-day view.
| Time | What You May See | Notes |
|---|---|---|
| Day 0 (birth) | Baseline weight recorded | Measured soon after drying |
| Days 1–3 | Loss of ~5–7% | Some reach up to ~10% |
| Days 3–4 | Weight loss slows | Feeding rhythm forms |
| Days 5–7 | Plateau then small gain | Plenty of wet diapers is reassuring |
| Days 10–14 | Back to birth weight | Many pass this point a bit earlier |
When To Call Your Pediatrician About Weight
Reach out if the scale shows a drop beyond about 10%, if feeding is hard, or if diapers are sparse. Signs of dehydration, sleepiness that limits feeding, or jaundice that worsens need prompt care. Your team can check latch or bottle technique, watch a feed, and plan follow-up weights.
Practical Tips For Weighing And Feeding
Use the same scale when you can and weigh at the same time of day. Remove heavy clothes or blankets. If a home scale is used, place a thin swaddle on top for comfort and tare it. Track feeds and diapers in a simple log. Frequent, effective feeds matter more than any single weigh-in.
Feeding Pointers
- Aim for 8–12 feeds across 24 hours in the early days.
- Watch for steady swallows and a relaxed body at the breast or bottle.
- Burp gently and switch sides or positions to keep the baby alert.
- Ask for hands-on help from a lactation nurse or your clinic if pain or poor transfer shows up.
Weight, Percentiles, And Growth Tracking
A single number at birth is a starting point. What matters next is the curve. Pediatric teams plot weight and length on standard percentiles and look for steady progress. Some babies track near the 15th percentile and thrive; others sit near the 85th and do the same. Consistent upward steps paired with good feeding and plenty of wet diapers tell a reassuring story.
Taking Context Into Account
Numbers should be read with the whole picture. A 2,650-gram baby born at 37 weeks, eating well and peeing often, can be perfectly healthy. A 4,200-gram baby with a tough start may need extra care. That is why teams pair the scale with a full exam, a feeding review, and the clinical history.
Weight By Gestational Week: The Broad Pattern
Within the term window, weight climbs from 37 to 40 weeks then often levels off. A baby at 39 weeks commonly lands near the average, while 41 or 42 weeks does not always mean a heavier newborn. Teams look beyond weight alone and watch movement, fluid on scan, and overall well-being in late pregnancy.
Preterm babies in neonatal care follow individualized plans that match calories and fluids to gestational age and feeding tolerance. Many born a bit early catch up during the first year.
How Delivery Details Can Nudge The Number
Timing of the first weigh-in matters. If the check happens before a large stool or urine, the number reads higher. Fluids given to the laboring parent can leave temporary extra water in a newborn’s tissues, a small bump that fades during the first days. That is why the trend across several days tells more than a single reading.
Length, Head Size, And Proportions
Newborn measurements come as a trio: weight, length, and head circumference. A light baby with a long length often comes from lean parents and feeds well. A heavy baby with a small length may simply have a sturdier build. Plotting all three on growth charts paints a clearer picture than any one number on its own.
Does Birth Weight Predict Later Size?
Birth weight offers a starting point, not a fixed path. Nutrition, sleep, family build, movement, and health events all shape growth over the months that follow. Plenty of light newborns grow into tall kids, and many heavy newborns settle into middle percentiles in infancy. Regular visits with your pediatrician keep the story current and the plan fits well.
Feeding, Milk Supply, And Weight Gain
Colostrum flows in small volumes at first and is rich in calories. Milk volume rises over the first few days. That is why skin-to-skin contact, frequent latch attempts, and rooming-in help weight rebound. Bottle-feeding families can promote gain by using responsive techniques: hold the baby upright, pause for cues, and switch sides so pacing stays calm. In both paths, burping and gentle waking methods like a diaper change keep feeds on track.
Home Weighing: Sensible Use
Home scales can be handy when a clinician asks for extra checks. Use them as a tool, not a daily test. A once-daily weight at the same hour gives enough data for a short period. Watch the baby: bright eyes, strong suck, soft hands opening during feeds, and a steady rhythm of wet and dirty diapers. Those signs pair with the scale to give a full picture.
Clinic teams take into account birth events, medications, and feeding method when reading the chart. Those details explain small swings and guide advice without leaning on the number alone over time, too.