December 24, 2017

Average Baby Weight May Surprise You

A full-term baby weighs around 7.5 pounds and measures around 20 inches. Twins can weigh as little as 5 pounds. Read on for more surprising facts.

© Gabriel Pinto (CC BY 2.0) via Flickr

Full-Term Babies

  • What is the average weight of a full-term baby?
    The average full-term baby weighs 7.63 pounds. Full-term means 40 weeks. However, the weight can range between 5 and 10 pounds and be considered "normal."

  • What is the average length of a full-term baby?
    A full-term birth can occur any time after 37 weeks. But twins are often born even earlier. On average, babies measure 20.16 inches at birth, if they make it to 40 weeks. Babies staying in the mother's womb for 41 weeks measure an average of 20.35 inches.

  • What is the average size of a newborn baby's head?
    The average newborn's head measures 13½ inches in circumference. However, by the time your baby turns 1-year-old, his/her head circumference should measure around 18 inches.

  • What is the average birth weight of full-term twins?
    Full-term twins are born around 37 weeks, as opposed to 39-40 weeks for single babies. Twins weigh an average of 5½ pounds at birth. However, one twin usually weighs more than the other.

  • What is the average weight of a 1-month-old baby?
    The average baby gains 2 pounds during its first month of life. The average baby born at 7.63 pounds will weigh around 9.63 pounds at its 1-month checkup.

What to Expect at Birth

  • What is the average weight of newborn boys in the 25th percentile?
    Newborn boys in the 25th percentile weigh an average of 6.7 pounds.

  • What is the average weight of newborn girls in the 25th percentile?
    Newborn girls weigh slightly less than newborn boys in the 25th percentile. Girls weigh an average of 6.5 pounds.

  • What is the average weight of newborn boys in the 75th percentile?
    Bigger baby boys in the 75th percentile weigh an average of 8.1 pounds.

  • What is the average weight of newborn girls in the 75th percentile?
    Newborn girls in the 25th percentile still don't break the 8-pound mark. They average 7.8 pounds.

  • What is considered a low birth weight?
    Babies that weigh less than 5 pounds 8 ounces at birth are considered low birth weight. Low birthweight babies are considered "premature." They often face complications. The issues include decreased oxygen levels, trouble gaining weight, and respiratory issues.

  • How many babies are considered low birth weight?
    Approximately 8% of the babies born in the U.S. are low birthweight or premature.

  • Can a 5-pound baby be healthy?
    Many 5-pound babies require a stay in the NICU. The treatment necessary varies based on the child's health. Many babies require beds that help control the baby's temperature, IV feedings, and care for respiratory issues. Barring any serious complications, low birthweight babies usually catch up to their peers over time.

  • How much should you feed a 5-pound baby?
    On average, babies eat 2.5 ounces of formula per pound of body weight. A 5-pound baby would then eat 12.5 ounces per day (24 hours). Of course, each baby differs based on needs and appetite.

  • What are the risks of a baby born at 7 months?
    Babies born at 7 months have not had time to fully develop. At just 32 weeks (7 months), the average baby weighs 3.75 pounds. Babies this small often have trouble eating, breathing, and regulating their temperature. Babies this small often stay in the NICU for proper care and development.

  • What is the average weight of a baby born at 35 weeks?
    Babies don't start gaining much weight until around 20 weeks gestation. Babies born early, at 35 weeks, weigh an average of 5.25 pounds. This is more than 2 pounds less than a full-term baby, which is just another 5 weeks.

  • What is considered a "big" baby at birth?
    A "big baby" has macrosomia, or a "large body." This term is reserved for babies that weigh more than 8 pounds at birth. The largest risk with big babies is difficulty birthing the baby.

  • Is a 21-inch newborn considered long?
    21 inches is about the end of the spectrum for the "average" newborn baby. Any baby measuring more than 21 inches may be considered "large."


  • How long is the average pregnancy?
    Today, the average pregnancy lasts 39 weeks, as opposed to the standard 40 weeks. However, a full-term baby is born anywhere between 39 weeks and 40 weeks and 6 days.

  • How many babies are born premature?
    As many as 15 million babies per year are born premature. Even scarier is the fact that every year, 1 million children die from complications of being premature.

  • How long is the average pregnancy with twins?
    On average, mothers pregnant with twins give birth by 35 weeks gestation. In fact, almost 60 percent of twins are born before 37 weeks gestation.

  • What percentage of pregnancies are high risk?
    High-risk pregnancies are scary; luckily, they only account for 8% of today's pregnancies. High-risk pregnancies occur as a result of a mother's pre-existing conditions as well as spontaneous issues that may occur.

  • How many births occur after the due date?
    Approximately 6.9% of births occur after their due date. 6.5% of the births occur by the 41st week and .4% occur after the 41st week.

  • Is a baby born 2 weeks after its due date considered "late"?
    A baby's due date is often an "estimate" based on the date of the mother's last menstrual period. Generally, a birth date within 2 weeks before or after the given date is considered normal. So being born 2 weeks "late" is technically not late.

The Bottom Line

Babies are unpredictable. They may be born right at 40 weeks or significantly before or after. Our hospitals today are adept at handling any type of situation. Always staying in contact with your doctor can help you understand your baby's weight and growth pattern. This can help you stay on track to have a full-term delivery.

Sources and References:

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It costs an adoptive family as much as $45,000 to adopt a child. However, 7% of the children in the U.S. are adopted. Each year more than 18,000 infants are adopted. Nevertheless, older children get adopted as well.

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