How babies are born

Why Do Babies Have More Bones than Adults?

An overview of how many bones babies are born with

Kathi Valeii is a freelance writer covering the intersections of health, parenting, and social justice.

Lyndsey Garbi, MD, is a pediatrician who is double board-certified in pediatrics and neonatology.

Did you know that at birth a baby has more bones in its body than an adult? Babies are born with about 270 bones, some of which will eventually fuse to form the 206–213 bones that they will have as adults.

Learn about how a baby’s bones change over time.

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Bones and What They’re Made Of

A baby’s bones consist of more cartilage than solid bone. Cartilage is more flexible than bone and is able to resist compression and provide support and flexibility.

Unlike bone, cartilage does not contain calcium in its matrix, the fibers and other substances that make up cartilage. Instead, cartilage contains the chemical chondroitin, which keeps it flexible and elastic. Cartilage also does not contain blood vessels or nerves. Instead, blood flow and pain sensations come from the surrounding structures.

Over time, much of the cartilage in a child’s body hardens into bone—a process called ossification. Ossification actually begins in utero around the sixth or seventh week of gestation and continues through a person’s mid-20s.

There are two types of bone ossification. They are called intramembranous and endochondral ossification, and they are responsible for the following bone formations:

The Bones That Babies Are Born With

Bones in the human body fall into three categories: long, short, and flat. A baby is born with bones and cartilage that will eventually ossify into these stronger bones.

Long bones evolve through endochondral ossification. Long bones are typically tubular, and they are longer than they are wide. The arms and legs are made up primarily of long bones.

Short bones also evolve through endochondral ossification, but they are not structurally similar to long bones. Instead, they take on distinct shapes. For example, the bones of the ankles, wrists, heels, and kneecaps are all short bones.

Flat bones evolve through intramembranous ossification. These bones have platelike shapes. The skull bones, the breastbone, shoulder blades, ribs, and hip bones are examples of flat bones.

The Ways That Bones Change as Babies Grow

A baby’s bones change from softer, flexible cartilage to harder, firmer bones over time. The process takes place from before birth until a person is an adult.

The Skull

Several bones make up the skull—two frontal bones, two parietal bones, and one occipital bone. Over time, these bones will fuse, but it is initially important that they remain flexible in order to go through the birth process and for brain growth.

Fontanelles are the spaces between the bones. There is one in the front (known as the soft spot) and one in the back of the head. They are covered by membranes that protect the underlying tissues and the brain.

The anterior fontanelle (soft spot) remains soft until a child is about 2 years of age. The posterior fontanelle usually closes by about 3 months of age.

Craniosynostosis

Craniosynostosis is a congenital disability (present from birth) in which the skull bones fuse too early. When this happens, as a baby’s brain grows, its skull can become misshapen. It occurs in one in 2,500 births in the United States. Oftentimes, surgery allows space for the brain to grow properly.

The Spine

A healthy adult’s spine has several natural curves—cervical (at the neck), thoracic (mid-back), and lumbar (at the base). The curves allow for proper mobility as we walk, bend, twist, and do everyday movements. However, our spines do not start out with these curves.

A baby’s spine begins in simple a C-shape. The thoracic curve begins to develop in utero, while the secondary cervical and lumbar curves do not develop until infancy, when a baby begins to lift its head, sit, crawl, and eventually stand and walk.

Spines can also curve abnormally. Kyphosis and lordosis are spine abnormalities that occur when a child’s front-to-back spinal curvature is too large. Scoliosis is a spine condition in which the spine is curved from side to side.

Scoliosis can be congenital or neuromuscular (a consequence of a muscular or neurological condition). The treatment depends on the severity of the condition and can include observation, bracing, or surgery.

Spina bifida is a neural tube defect that affects the spine. It occurs when the neural tube (which becomes the brain and spinal cord) does not close all the way during early embryonic development. When this happens, the bones that are supposed to protect the spinal cord do not form and close, which damages the spinal cord and surrounding nerves.

Spina bifida can result in physical and intellectual disabilities, but not everyone with spina bifida will have disabilities. The treatment depends on the severity of the condition and may include surgery or mobility aids, like wheelchairs, braces, crutches, and walkers.

The causes of spina bifida are not completely understood. However, one known way to reduce the risk of the condition is to take folic acid supplements if you are trying to conceive and while you are pregnant.

Arms and Legs

Ossification of the long bones actually begins in the fetal stage. Ossification of the limbs is not complete until the late teens to mid-20s.

Long bones in children are divided into four regions: diaphysis, metaphysis, physis, and epiphysis.

Only the metaphysis and diaphysis are present in adults. The epiphysis is mostly cartilage in infants. Over time, it gradually ossifies until it becomes almost completely replaced by bone in a person’s late teens.

Children’s bones are more flexible and have a thicker covering, making them more able to absorb shock and resist fractures. At the same time, kids are more prone to some kinds of fractures in areas that are no longer present in adults, such as growth plates.

If growth plates (tissue near the ends of bones) do not heal properly, bones may grow crooked or more slowly. For this reason, a doctor will want to monitor a child’s bone for a year or more after a fracture.

Rare Bone Disorders

Achondroplasia is a rare genetic bone disorder that prevents cartilage from being made into bone. It causes a child to develop with short arms, legs, and a larger head. The condition is a form of dwarfism. People with achondroplasia have typical intelligence and life spans.

Hypochondrogenesis is a rare genetic condition that causes a fetus to develop shorter limbs, a small body, and abnormal ossification of the spine and pelvis. The condition is usually fatal before birth or shortly after.

Other Facts About Bones

Bones are a fascinating part of the human body. A child’s bones are constantly changing, with bones developing into new, different bones all the time.

Here are some other interesting facts about bones that you might not know:

Frequently Asked Questions

How can I keep my baby’s bones healthy?

Being a positive role model is a great way to establish good habits in your kids. Good nutrition and physical activity are the two factors that influence bone growth and health. For the first year, your child will receive adequate nutrition through breast milk or formula. After that, make sure your child gets plenty of foods that are rich in calcium and vitamin D.

When will my baby’s bones fuse?

The process of bones fusing is called ossification. Ossification doesn’t happen all at once. Instead, it is a process that begins in utero and continues until the skeleton is mature—usually in a person’s 20s.

When will my baby’s skull fuse?

A baby’s skull is made up of five bony plates. The spaces between these bones are called the fontanelles.

There is one fontanelle in the front of the head (called the anterior fontanelle or the soft spot) and one in the back (called the posterior fontanelle).

The posterior fontanelle closes during the first few months of life. The anterior fontanelle closes at around 18–24 months.

A Word From Verywell

Your child’s bones are changing and growing significantly during childhood and adolescence. You can help your kids develop healthy bones by making sure that they are well-nourished and stay active.

When your child begins eating solid foods, ensure that their diet provides sufficient calcium and vitamin D for their age. As they get older, weight-bearing activities, such as walking, running, hiking, and playing sports, and resistance exercises like lifting weights are great ways to build healthy bones.

Cowan P, Kahai P. Anatomy, bones. National Institutes of Health, National Library of Medicine.

Chang L, Marston G, Martin A. Anatomy, cartilage. National Institutes of Health, National Library of Medicine.

Breeland G, Sinkler M, Menezes R. Embryology, bone ossification. National Institutes of Health, National Library of Medicine.

Centers for Disease Control and Prevention. Facts about craniosynostosis.

Boston Children’s Hospital. Spine problems.

American Association of Neurological Surgeons. Scoliosis – symptoms, diagnosis and treatment.

Centers for Disease Control and Prevention. What is spina bifida?.

American Academy of Pediatrics. Children and broken bones.

U.S. National Library of Medicine. Hypochondrogenesis.

National Institutes of Health. Kids and their bones: A guide for parents.

How babies are born

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This little girl is having a hard time trying to explain to the doctor how babies are born. Yes, it’s not easy, grown-ups can sometimes be so thick!

One of the most hilarious moments of The Bill Cosby Show.

WHAT DO YOU DO?= What’s your job.
You can also say: What do you do for a living?

DELIVER= The act of bringing a baby from inside a woman’s body to the outside world. A doctor delivers a baby when he makes it come out, and a woman delivers a baby by pushing it out, so the baby is born.

STORK= A big black and white bird from Europe that spends the winter cold in Africa and often builds its nest on top of church roofs. In European tradition, children were told that storks bring the babies from heaven in a bundle of cloth held with their beaks and flew them down into the right house. This little girl here has a bit more modernized version of the myth which includes storks dropping their babies in the hospital, not in the houses. (see picture of a stork)

BASSINET= A basket with a hood over one end, for use as a baby’s cradle. (see picture)

WHY IS IT THAT. = An emphatic version of WHY:
— Why is it that you’re tired? = Why are you tired?
More common as part of a subordinate sentence:
— If you spent all the day at home, why is it that I saw you having a drink with Jimmy at the bar at 5 o’clock?

LET ME GET THIS STRAIGHT= Let’s see if I have understood that correctly.
We say this when we want to make sure that we have understood what the other person is telling us and we want to explain what we think they are trying to say, so that we get confirmation from them.
— Oh yes, Frank is very nice and all that, and he’s sexy and handsome and I have lots of fun with him, but he’s not exactly what I’m looking for.
— Ok, ok, let me get this straight. Are you saying that Frank is the perfect man but he’s not good enough for you?!
— Well, I wouldn’t put it that way, but yes, I guess that’s correct.

REAL BIG= (esp. AmE) Really big, very big.

YOU GOT IT!= (coll.) That’s right; you understood correctly.

I SEE= Ok, I understand.

WINGS= Birds don’t have arms, they have wings and they fly by moving them.

HEAVEN= The spiritual dimension where God is and where people who die go if they’ve been good. Heaven is not a place, it’s a dimension, but for practical purposes in our imagination heaven is up there in the sky, so sometimes we use “heaven” just to mean “the sky”. In this case it is not clear what sense of heaven the little girl has in mind, but probably a mixture of both: heaven is up in the sky, God creates the babies up there and the storks are a kind of angels that go up there, pick the babies and bring them down to earth.

A ZILLION SKILLION= (especially baby or humour language) A zillion is a very very big number, millions of millions. A zillion skillion is a number much much bigger than a zillion, more or less similar to a megazillion 🙂

LIKE YOU GO= (coll. esp. AmE) As if you went. as when you go.
Using LIKE as a comparative conjunction is very common in American English and also in colloquial British English. In standard BrE LIKE can be a preposition or a verb, but not a conjunction:
— I like children (verb)
— The moon is like a big white cheese (preposition)
— I feel like I have fire inside my stomach (conjunction: AmE and colloquial BrE)
— I feel as if I had fire inside my stomach (conjunction: standard BrE)

THE BAKER= A shop where you can buy bread, and usually confectionery too (cakes, biscuits, etc.). A baker, or bakerman, is the person who makes bread, but here it means the shop where they sell bread. The exact word should be “the bakery”, but you could also say “the baker’s shop”, which most of the times simply gets into “the baker’s”, but today you can also hear “the baker”, especially in American English, without – ‘s – referring to the shop, not to the person who makes bread.

YOU’RE WELCOME (AmE) = Not at all (BrE)

I’M IN CHARGE OF= If you are in charge of something, you are responsible for that, you work with that or you supervise that.

Parents Say: How can I explain to my child how babies are born?

Little kids ask a lot of questions. Some are easy to answer. Others, not so much…

Here’s how some BabyCenter parents handled one of the more challenging questions you’re likely to hear.

Keep it simple

«You might ask your child how she thinks it happens, and use that as your starting point. For example, if she thinks, as my son does, that the baby comes through the belly button, you could gently correct her by saying that she’s close, but the baby comes out a different hole. That might be explanation enough.»
— A BabyCenter member

«My son is 3, and I’m pregnant with our second child. I told him the doctor helps «move» the baby out of Mommy’s tummy and into a nice warm blanket. I used the word «move» instead of «push» so as not to confuse him, and I concentrated more on the warm blanket and him being a big brother.»
— Melissa

«Never answer a question that your child isn’t asking. My own child asked how a friend was going to get her baby out. I simply said that she was going to push the baby out. He was fine with that. A few years later he asked exactly where babies came out, and that’s when I told him.»
— A BabyCenter member

Try show and tell

«I happened to be preparing dinner when my son asked how the baby would come out of me and how the doctor would see the baby. I explained the best I could about how you can see inside women, and the baby would come out the same area that the doctor had to look into. I was seasoning a raw chicken, and I used it to illustrate how the baby would be in the chicken’s tummy and come out of the opening in the bottom. (Yes, I know chickens lay eggs.) The light came on, and he finally seemed to understand. I just hope I didn’t ruin chicken for him for the rest of his life!»
— A BabyCenter member

«As a childbirth educator, I’ve found that a turtleneck shirt and a doll are very effective for helping children understand the process. I hide the doll in the shirt and then hold it against my belly with neck opening facing down. Then I tell my 2-year-old that the baby is in there, warm and comfy and happy, and when it’s time for the baby to be born, my belly will squeeze the baby and push it out. Then I squeeze the shirt until the baby comes out the opening.»
— JD

«This past weekend my son attended a class called Kangaroo Kapers at our hospital’s birth center. He toured the area, practiced changing diapers on a doll, and learned about holding and swaddling a baby. The instructors did not go into graphic detail but offered a child-friendly version of what was going to happen the day the baby came, including how Mommy was going to be cranky in the delivery room. They showed him all the equipment and explained its use. I would highly recommend checking out similar classes in your area.»
— M. Parrish

Watch a good video

«My 2-year-old and I watched a video of a dog having puppies. He asked if someone was going to pull out our baby too. I told him that my doctor would be there to catch the baby, but that the baby and my body will work together to get the baby out. He was completely satisfied by that answer and then focused on the fact that I wouldn’t have to lick our baby clean like the dog did because we can use towels!»
— A BabyCenter member

«My 3-year-old has watched her own birth video and knows anatomically correct wording. She says, «Baby Petey is going to open the uterus door and come out of Mommy’s vagina with contractions when it’s time.» Just use your instincts and feel out what your child can handle, but make sure you are comfortable with your answers first, as kids can pick up on all of your emotions about a subject if you are uncomfortable.»
— Elizabeth

«My 4-year-old asked how the baby will be born, and I showed him a short video that I found on BabyCenter. He watched it once, and we talked about how the baby pushes to get out and how the mommy helps by pushing too. My son will be in the delivery room with us, so my husband and I were very worried how he would react. We decided that broaching the subject beforehand without any of the mystery was best. It also helped that he watches a lot of nature shows and already knows that girls are the ones giving birth. But he still asks me if I’m going to have an egg and have to sit on it.»
— A BabyCenter member

Read a children’s book on the topic

«I have a book for my 4-year-old called When You Were Inside Mommy, by Joanna Cole. It explains how you begin as a cell – half from Mom, half from Dad – and you grow from there. No unnecessary graphics or details. I even skip over some of the sentences I don’t think he will grasp. He loves it, and we read it every night before bed.»
— A BabyCenter member

«A great book called What to Expect When Mommy’s Having a Baby, by Heidi Murkoff, explains the whole process very simply, and you can read as much or as little as you want to fit your child’s developmental level. It seems to be aimed at children ages 3 to 6.»
— Katie

You Were Born on Your Very First Birthday, by Linda Walvoord Girard, does a good job of explaining birth without going into too much detail, which my 4-year-old is not ready for yet.
— Angie

«I think the book A Child Is Born, by Lennart Nilsson and Lars Hamberger, is an excellent resource. It has photos of everything from conception to birth and shows the fetus in all stages of development. I will choose which pictures to show my children depending on their ages.»
— Yeeska

What to know about premature babies’ survival rates and health outcomes

While your preemie or micropreemie may look so tiny and fragile, a stay at the NICU will give them a fighting chance to live and thrive. Just consider these odds – a baby born at 28 weeks of pregnancy has an 80 percent chance of living and a 9 in 10 chance of growing up healthy. And those numbers only get better the later during pregnancy a preemie baby is born.

What does it mean to be preterm?

Babies are preterm if they’re born before your 37 th week of pregnancy. Compare that to a full-term infant who’s born between 39 weeks through the 40 th week of pregnancy. About 1 in 10 babies in the U.S. were born premature in 2020, according to the Centers for Disease Control and Prevention. But those stats can be deceiving because the rate of preterm births among Black women is 14 percent, or almost twice that as White women (9 percent).

Doctors tend to group preemies into four main categories, depending on what week they were born. These categories range from extremely preterm (babies born before week 25) to late preterm (preemies born between 34 and 36 weeks). Premature babies are also grouped according to birth weight. Girl babies tend to be smaller than boys, no matter what week they’re born, and if you have multiples, those babies each usually weigh less than singletons.

Preemie babies, especially those born extremely early and at the lowest birth weight (under 2 or even 3 pounds), are at higher risk for health complications and disabilities. But luckily, there have been so many medical breakthroughs that preemies today have better chances of surviving and thriving than even 15 years ago. With good care in the hospital and at home, a preemie baby will grow up and live a full, healthy life – as a child and adult.

What is a micro preemie?

Micropreemie is the term doctors use for babies either born before the 26 th week of pregnancy or weighing less than 1.75 pounds (28 ounces) at birth. Because they’re so tiny and weigh so little, micropreemies are at greater risk than even a preemie baby for health issues and disabilities as they grow older. Still, hospitals are doing amazing things to take care of micropreemies – even those born super early – and making sure they have the best odds of overcoming their challenges.

How early can a baby be born and survive?

Usually, after week 22. It’s rare that premature babies born before week 22 survive. But micropreemies born between 22 and 26 weeks will need lots of medical attention to prevent any lasting damage to their brains, lungs, and other organs. That’s because babies continue to grow and develop right up until 39 weeks, so the longer your baby stays inside the womb, the better their health.

Even micropreemies have a fighting chance, though, thanks to technology and medical advances. In a study of roughly 11,000 extremely premature babies, those born at 22 weeks had a 28 percent survival rate, while those born at 23 weeks had a 55 percent survival rate. But the even better news in the study came when researchers looked at these babies at 2 years old. About half of these micropreemies (born between 22 and 26 weeks) had no or mild disabilities and another 29 percent had moderate ones. Only 21 percent of preemies had severe disabilities like cerebral palsy, blindness, or neurological delays.

Besides age, there are other factors that play a role in a baby’s chances of survival. They include birth weight, gender (girls have a higher rate of survival), the mom’s age and health, pregnancy or birth complications, whether the baby is a singleton or a multiple (single babies have a better rate of survival), and whether there are any genetic abnormalities.

Outlook for a baby born at 26 to 28 weeks

Average weight: 1 pound, 12 ounces (0.8 kg) to 2 pounds, 7 ounces (1.1 kg)

Average length: 13 inches (33 cm) to 14.4 inches (36.5 cm)

Average head circumference: 9 inches (23 cm) to 10.2 inches (26 cm)

Known as: Extremely preterm babies

About 1.5 percent of preemies in this country are born this early. Between 80 and 90 percent of premature babies who reach 28 weeks gestation survive. And only 1 in 10 preemies born at 28 weeks have long-lasting health problems.

However, these extremely preterm babies are at a higher risk for medical complications and may face an extended stay in the neonatal intensive care unit (NICU).

Here’s what to expect:

Outlook for a baby born at 28 to 32 weeks

Weight: Between 2 pounds, 3.3 ounces (1 kg) and 3 pounds, 15.5 ounces (1.8 kg)

Length: Between 14.1 inches (36 cm) and 16 1/2 inches (42 cm)

Head circumference: Between 9.8 inches (25 cm) and 11 1/2 inches (29.5 cm)

Known as: Very preterm

About 1.5 percent of all babies arrive in this time period. Twins, triplets (or more) are 9 times more likely than singletons to be very premature. Babies born between these weeks have an excellent chance of staying alive, and 90 percent will have no or minimal long-term health or developmental problems.

Here’s what to expect:

Outlook for a baby born at 32 to 34 weeks

Weight: Between 3 pounds, 12 ounces (1.7 kg) and 4 pounds, 14 ounces (2 kg)

Length: Between 16.5 inches (42 cm) and 17 1/2 inches (44 1/2 cm)

Head circumference: Between 11.4 inches (29 cm) and 12 inches (31 cm)

Known as: Moderately preterm

About 1.5 percent of all babies arrive at this time, and about 95 percent of them survive. Moderately preterm babies are less likely than babies born earlier to develop serious disabilities resulting from premature birth, though they may have a higher risk than full-term babies for learning and behavioral problems.

Here’s what to expect:

Outlook for a baby born at 34 to just under 37 weeks

Weight: Between 5 pounds, 11 ounces (2 kg) and 6 pounds, 7 ounces (3 kg)

Length: Between 17 inches (44 cm) and 19 inches (48 cm)

Head circumference: Between 12 inches (31 cm) and 13 inches (33 cm)

The majority of preemie babies, or 7.4 percent, are born late preterm. Preemies born after 34 weeks have the same chance of being healthy as full-term babies. They’re less likely to develop serious disabilities (especially compared to preemies and micropreemies) though they probably will hit developmental milestones later.

Here’s what to expect:

Learn more:

Sources

BabyCenter’s editorial team is committed to providing the most helpful and trustworthy pregnancy and parenting information in the world. When creating and updating content, we rely on credible sources: respected health organizations, professional groups of doctors and other experts, and published studies in peer-reviewed journals. We believe you should always know the source of the information you’re seeing. Learn more about our editorial and medical review policies.

Surprising things to know about pregnancy in the U.S.

When it comes to pregnancy and fertility in the United States, there are many statistics and facts to unpack. The most recent numbers show that births, birth rates, and fertility rates all declined in 2019, making this the fifth consecutive year that the number of births declined. In addition to those numbers, the U.S. fertility rate hit a record low. However, more women began prenatal care in the first trimester, fewer women smoked during pregnancy, and the cesarean delivery rate decreased.

How many babies are born in a day?

Worldwide, around 385,000 babies are born each day. In the United States in 2019, about 10,267 babies were born each day. That’s 1 percent less than in 2018 and the fifth year in a row that the number of births has declined.

Preliminary data for 2020 show another decline in birth numbers – this time of 4 percent, which will be the lowest number of births since 1979.

Experts are predicting a continued drop in 2021, too, perhaps as a result of women postponing pregnancies in light of the COVID-19 pandemic. There was an 8 percent decline in babies conceived in December 2020 compared to the previous December.

What day are the most babies born?

The most popular day for babies to make their entrance in 2019 was Tuesday, followed by Thursday. Sunday was the slowest day, followed by Saturday. Scheduled c-sections and induced labors have a big influence on the reason why far fewer babies are born on the weekend, but spontaneous (unscheduled) deliveries occur less often on the weekend too.

What time of day are the most babies born?

The highest percentages of births in 2019 occurred during the midday hours (noon to 3), followed by the morning hours of 9 to noon. The fewest babies were born between midnight and 6:59 am.

What month are the most babies born?

In 2019, more newborns arrived in August than in any other month. The second, third, and fourth most popular birthday months were July, September, and October, in that order. The least busy month for birth days was February.

According to preliminary data, the number of births for the U.S. declined for each month in 2020 and larger declines in births were seen in the second half of 2020 compared with the first half of the year.

Birth numbers and birth rates among states

The birth rate in the United States in 2019 was 11.4, meaning there were 11.4 births per every 1,000 Americans.

According to provisional data, 20 states reported declines in the number of births in the first half of 2020 compared with the same time period in 2019. Thirty states and DC reported no significant change.

For the second half of 2020, provisional data show the number of births declined for all states. The states that saw the largest declines in the second half of 2020 were New Mexico and New York. Thirty-eight states and DC reported declines of 3 to 7 percent.

States with the most births and highest birth rates

The most number of births in 2019 were in California, Texas, and New York.

States with the highest birth rates were Utah, North Dakota, Alaska, and Texas.

States with the fewest births and lowest birth rates

Vermont had the fewest births, followed by Wyoming, the District of Columbia, and Alaska.

States with the lowest birth rates were Vermont, New Hampshire, Maine, Rhode Island, Oregon, and Connecticut.

Fertility rates in the US

The general fertility rate (GFR), or number of births per 1,000 women aged 15 to 44 years was 58.3 in 2019. This was a decrease of 1 percent from 2018 and a record low.

Provisional data for 2020 show the GFR at 55.8 births per 1,000 women, down another 4 percent from 2019, and another record low. From 2014 to 2020, the GRF has declined by an average of 2 percent per year.

States with the highest fertility rates

North Dakota and South Dakota shared the highest fertility rate, followed by Alaska, Utah, and Nebraska.

States with the lowest fertility rates

Vermont has the lowest fertility rate, followed by New Hampshire, Rhode Island, and Massachusetts.

Total Fertility Rate

The Total Fertility Rate (TFR) estimates the number of births that a group of 1,000 women would have over their lifetimes, based on the age-specific birth rate in a given year. The TFR for 2019 was down 1 percent from 2018, to 1,706 births per 1,000 women.

Births by age

Over the last three decades, women have been waiting longer to have children. In 1970, the average age of a first-time mother was 21.4. In 2019, the average age was 27.0, an increase from 26.9 in 2018, and a record high. Fewer teens and fewer women in their early 20s are having their first babies.

Prenatal health habits

Prenatal care

The percentage of women receiving prenatal care in the first trimester of pregnancy was 77.6 percent in 2019, up slightly from 77.5 percent in 2018. Sixteen percent of women began prenatal care in the second trimester, 4.5 in the third trimester, 6.4 percent received «late or no care,» and 1.8 percent received no care.

Women aged 35 to 39 were the one group less likely to receive first trimester prenatal care in 2019 than in 2018. Late (beginning in the third trimester) or no prenatal care increased from 6.2 percent to 6.4 percent.

The NIH is studying the effects of the COVID-19 pandemic during and after pregnancy. They’re examining the records of 21,000 women to see if changes to prenatal healthcare that were implemented as a result of the pandemic led to a higher rate of pregnancy-related complications and cesarean deliveries.

Pregnancy weight gain

About one-third of women gain the recommended amount of weight during pregnancy. Twenty-one percent gain too little weight, and 48 percent gain more than recommended. In 2019, 55.9 percent of women were overweight or obese (had a BMI of 25.0 or more) during pregnancy.

Gestational weight gain recommendations vary based on a woman’s pre-pregnancy weight and height. Inadequate weight gain is associated with a higher risk of problems such as low birth weight and preterm birth, while excessive weight gain is linked to problems including gestational diabetes, preeclampsia, c-sections, and weight retention after pregnancy.

Smoking in pregnancy

In 2019, 6 percent of pregnant women reported smoking tobacco during pregnancy, down 8 percent from 2018. Use was most common in early pregnancy – 5.8 percent of women smoked in their first trimester, 5 percent in their second, and 4.7 percent in their third. Smoking rates were highest among women aged 20 to 24 and lowest among women aged 40 to 54.

Fertility treatment

In 2019, 2 percent of pregnancies resulted from fertility treatments like in-vitro fertilization (IVF) or intrauterine insemination (IUI).

Where and how women are giving birth

Birthplace

Medical attendant

The vast majority of births have a Doctor of Medicine (MD) present, nearly 80 percent, in fact, and about 10 percent have a Doctor of Osteopathy (DO) present.

Fetal presentation

The most common position for a baby to be in at the time of delivery is head down, facing mom’s back. This is called cephalic presentation and a whopping 94.91 percent of all births occur in this position. Just over 4 percent of births involve babies who are breech, or bottom-down.

C-sections

The cesarean birth rate decreased slightly to 31.7 percent in 2019, the lowest rate since 2006.

Rates of cesarean delivery decreased for all age groups except 35-39 (for which it was unchanged), and overall, cesarean deliveries are higher among older women.

The vaginal birth after cesarean (VBAC) delivery rate is the number of births to women having a vaginal delivery per 100 births to women with a previous cesarean delivery.

The vaginal birth after previous cesarean delivery rate was 13.8 percent in 2019, up 4 percent from 2018. The rate has increased every year since 2016 (the year when national data became available).

Induction and other techniques

The number of women who had labor inductions has more than doubled since 1990. In 2019, 29.4 percent of labors were induced, compared with 22.8 percent in 2012.

Forceps and vacuum extraction deliveries were rare. Forceps were used in 0.69 percent of deliveries, and vacuum extraction was used in 3.45 percent of deliveries.

Premature babies

The percentage of babies born preterm (less than 37 completed weeks of gestation) was 10.23 percent, up 2 percent from 2018. This is the fifth straight year that the rate has risen.

Newborn health

Boys vs. girls

With about 105 male babies born for every 100 female babies born in 2019, boys are keeping the edge in a ratio that’s stayed about the same for the last 60 years.

Total female births in 2019: 1,830,094

Total male births in 2019: 1,917,446

Multiples

Twins

The number of twins born in the United States decreased by 3 percent in 2019. The 2019 twin birth rate declined 2 percent, to 32.1 twins per 1,000 births, a 5 percent decline from the 2014 high of 33.9.

Triplets and more

There were 3,286 multiples born in 2019, which is the lowest number reported since 1990 and less than one-half the highest number reported in 2003. The triplet and higher-order multiple birth rate also declined in 2019.

Weight at birth

The average birthweight of babies born in 2019 was 7.17 pounds.

Low birth weight

The percentage of babies born in 2019 at a low birth weight (LBW) – which is defined as less than 5 pounds, 8 ounces – was 8.31, up insignificantly from 8.28 percent in 2018. (LBW includes babies born preterm as well as those born in term.) These are the highest rates since 2006.

Very low birth weight

The very low birth weight (VLBW) rate in 2019, which accounted for babies weighing less than 1,500 grams, was 1.4 percent, unchanged from 2018.

NICU stays

In 2019, almost 350,000 newborns were admitted to the NICU at birth. That might sound like a lot, but keep in mind that over 3 million newborns did not require NICU care. And at discharge, 83.6 percent of infants were being breastfed.

Apgar Scores

An Apgar test tells how well your baby is doing just after birth, at one and five minutes. It assesses Activity (spontaneous movement), Pulse (heart rate), Grimace (reflex activity such as gagging in response to suctioning), Appearance, (color) and Respiration (breathing). A score of 7 to 10 is considered normal for a five-minute Apgar test. Nearly 85 percent of babies born in 2019 received an Apgar score between 9 and 10, and just 0.58 percent received a score of 0 to 3.

For more CDC birth data, visit the agency’s Births and Natality page.

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Sources

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