At 23 weeks, the baby is about 11.5 inches long and weighs roughly 1.1 pounds. Find out the typical size, growth milestones, and what to expect in this pregnancy stage.
By Shubhra Mishra — a mom of two who turned her own confusion during pregnancy into BumpBites, a global mission to make food choices clear, safe, and stress-free for every expecting mother. 💛
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Quick take: At 23 weeks pregnant, the baby is about the size of a large mango—roughly 11.5 inches (29 cm) long and weighing around 2 ounces (57 g). This size is typical for this stage, and ultrasound measurements help confirm healthy growth.
It’s 2 a.m., you’re scrolling through pregnancy forums, and a blurry ultrasound image pops up on your screen. You wonder, “Is my baby’s size normal?” You’re not alone—many expectant parents hit that exact moment of uncertainty. The good news is that by week 23, doctors have a solid benchmark for how big a baby should be, what milestones are unfolding, and what variations are still within the normal range.
In this guide we’ll answer the most common questions about a 23‑week baby’s size: exact length and weight, how it compares to fruit, how it stacks up against weeks 22 and 24, and what the ultrasound numbers really mean. We’ll also explore the developmental milestones happening right now, the factors that can influence size, and how to interpret your ultrasound report with confidence.
Whether you’re tracking growth charts, prepping for a 23‑week scan, or just need reassurance, you’ll find clear, evidence‑based answers backed by ACOG, NHS, and WHO guidelines. Let’s dive in.
How big is a baby at 23 weeks pregnant?
At 23 weeks gestation, the fetus measures approximately 11.5 inches (29 centimeters) from crown to rump. This length is measured from the top of the head to the bottom of the torso, not including the legs, which are still curled. In terms of volume, the baby’s head is about the size of a small orange, while the body resembles a large mango.
Most clinicians use the biparietal diameter (BPD) and femur length (FL) to estimate overall size. The average BPD at this stage is 6.5 cm, and the femur length averages 3.5 cm. Combining these measurements with abdominal circumference (AC) gives a reliable picture of growth.
Because growth isn’t perfectly linear, a baby can be a few centimeters shorter or longer and still be considered healthy. The key is that the measurements fall within the 10th‑90th percentile range on standardized growth charts, such as those from the World Health Organization (WHO) and the American College of Obstetricians and Gynecologists (ACOG).
It’s also worth noting that the uterus at 23 weeks has expanded to about the size of a football, giving the baby enough room to move freely while still being protected by amniotic fluid. This expansion is a sign that the placenta is efficiently delivering nutrients, a factor that directly influences fetal size.
23 weeks pregnant baby size chart in cm
Gestational Week
Length (cm)
Weight (g)
22
27.5
48
23
29.0
57
24
30.5
68
What does a 23‑week baby look like on ultrasound?
On a typical 2‑D ultrasound, the baby’s limbs are proportionate, and you can often see the beginnings of eyelids, eyebrows, and even the outline of the vocal cords. The skin is still translucent, but the fetus has a distinct, rounded shape. You might notice the baby’s hands flexing around the tiny fingers, and the first hints of lanugo—fine, downy hair covering the body.
Factors that affect 23‑week baby size
Genetics play a major role; babies often follow the growth patterns of their parents. Maternal nutrition, especially protein and micronutrient intake, can influence weight gain. Chronic conditions like hypertension or diabetes may cause the baby to grow larger (macrosomia) or smaller (growth restriction). Smoking, alcohol, and certain medications also affect size, typically resulting in lower birth weight.
Seasonal variations in vitamin D levels and maternal stress hormones have also been linked in recent cohort studies to modest shifts in fetal size, underscoring the importance of holistic prenatal care.
How to measure baby size at 23 weeks with ultrasound
During the scan, the sonographer will capture three key measurements:
Biparietal diameter (BPD): Width of the head.
Head circumference (HC): Circumference around the skull.
Abdominal circumference (AC): Around the abdomen.
Femur length (FL): Length of the thigh bone.
These numbers are entered into growth‑chart calculators to estimate fetal weight (EFW). The process is non‑invasive and takes only a few minutes, providing a snapshot of how the baby is progressing.
Typical 23‑week ultrasound view, highlighting head and limb development.
23 weeks pregnant baby weight in ounces
By the 23rd week, the average fetal weight is roughly 2 ounces, which translates to about 57 grams. This is comparable to the weight of a small plum or a handful of grapes. While the baby’s weight increases rapidly—gaining about 0.5 oz (15 g) each week—there’s a wide normal range. Some babies may weigh as little as 1.5 oz (42 g) or as much as 2.5 oz (71 g) and still be thriving.
Weight estimates are derived from the same ultrasound measurements mentioned earlier (BPD, HC, AC, FL). The Hadlock formula, endorsed by ACOG, is the most common algorithm for converting these dimensions into an estimated fetal weight (EFW). It’s important to remember that the EFW is an estimate, not an exact number.
Average weight of a 23‑week fetus in grams
Across large population studies, the mean weight at 23 weeks is 57 g, with a standard deviation of about 12 g. This means that roughly 68 % of babies fall between 45 g and 69 g. The 10th percentile sits near 38 g, and the 90th percentile around 76 g. Clinicians use these percentiles to flag potential growth concerns.
23 weeks fetal size vs 24 weeks growth
Between weeks 23 and 24, the baby typically grows an additional 1.5 inches (3.8 cm) in length and gains about 0.5 oz (15 g) in weight. This accelerated growth reflects rapid organ development, especially in the brain and lungs. If a 23‑week scan shows size at the lower end of the normal range, the provider will monitor closely to ensure the baby catches up by week 24.
Fetal size variations at 23 weeks pregnancy
Variations can stem from:
Maternal body mass index (BMI) – higher BMI often correlates with larger fetal size.
Placental health – a well‑vascularized placenta supports better growth.
Genetic factors – twins or multiples tend to be smaller individually.
Maternal illnesses – hypertension or infections can restrict growth.
Even with these variations, most babies stay within the accepted percentile ranges, so a modest deviation isn’t usually cause for alarm.
23 week fetal length in inches and centimeters
The crown‑to‑rump length (CRL) at 23 weeks averages 11.5 inches (29 cm). This measurement is taken from the top of the head to the bottom of the torso, excluding the legs, which are curled under the body. The femur length, representing the thigh bone, adds roughly 3.5 cm (1.4 inches) to the overall limb length when the baby is fully extended.
In practical terms, the baby’s length is comparable to a large mango or a small pineapple. If you hold a mango in your hand, you can picture the baby’s size at this stage—still small enough to fit comfortably in the womb, yet large enough to see distinct facial features.
What fruit size is a 23‑week fetus comparable to?
Most clinicians and parents liken a 23‑week fetus to a large mango, a small papaya, or a ripe cantaloupe slice. These fruits share a similar length and girth, making the comparison both visual and relatable. The fruit analogy helps demystify fetal growth for those who struggle to imagine measurements in abstract terms.
How to interpret 23 week ultrasound size measurements
When your provider reviews the ultrasound, they’ll compare the BPD, HC, AC, and FL to established growth charts. If the values line up within the 10th‑90th percentile, the size is deemed appropriate. Deviations beyond these ranges may prompt additional testing, such as Doppler studies to assess blood flow, or repeat scans in a few weeks.
Developmental milestones for a 23 week baby
At 23 weeks, the baby’s brain is undergoing a remarkable surge in neuron formation. The cerebral cortex, responsible for thinking and sensory processing, is thickening rapidly. This development underpins several observable milestones:
Sensory perception: The baby can now respond to sounds, turning its head toward familiar voices.
Movement: Fine motor skills improve; the baby can grasp its own thumb and make coordinated movements.
Sleep‑wake cycles: More defined patterns emerge, with periods of REM sleep that are crucial for brain development.
Skin changes: The translucent skin becomes more opaque as a thin layer of vernix caseosa forms, protecting the baby’s skin.
These milestones are visible on ultrasound as increased activity, more defined facial features, and stronger limb movements. While you can’t feel these changes directly, many expectant parents notice a “kick” or “roll” more frequently around this time.
What can a 23‑week fetus do?
The baby can now open and close its eyes, though the eyelids remain fused. It can also make sucking motions, a reflex that prepares it for feeding after birth. The respiratory system is developing bronchi and bronchioles, but the lungs are still immature and will continue to mature well into the third trimester.
Developmental health indicators at 23 weeks
Consistent growth, active movements, and appropriate heart rate (120‑160 bpm) are reassuring signs. Any significant reduction in movement, abnormal heart rate, or measurements outside the normal range should be discussed with a provider promptly.
Think of a large mango to visualize the length of a 23‑week baby.
Is a 23 week baby size considered normal?
Yes. When ultrasound measurements fall within the 10th‑90th percentile range, the size is classified as normal. This range accounts for genetic diversity, maternal health, and environmental factors. Most clinicians consider a fetus “appropriate for gestational age” (AGA) if it meets these criteria.
However, “normal” does not guarantee the same exact size for every baby. Some babies will be slightly larger or smaller, and both scenarios can be perfectly healthy. The key is consistent growth over time. A single measurement that is a little low or high is less concerning than a trend that moves consistently away from the norm.
Typical size variations and what is considered normal
At 23 weeks, a typical length variation spans 10‑12 cm, and weight can vary by ±15 g. The 10th percentile for length is about 27 cm (10.6 in), while the 90th percentile reaches around 31 cm (12.2 in). For weight, the 10th percentile sits near 38 g (1.3 oz), and the 90th percentile near 76 g (2.7 oz).
If your baby’s measurements fall within these ranges, the provider will usually reassure you that growth is on track. If measurements fall outside, further evaluation—such as a detailed anatomy scan or Doppler flow study—may be recommended.
23 weeks pregnant baby size compared to 22 weeks
Comparing week 22 to week 23 highlights the rapid growth occurring in the third trimester. At 22 weeks, the average length is about 27.5 cm (10.8 in) and weight roughly 48 g (1.7 oz). By week 23, the baby gains approximately 1.5 cm (0.6 in) in length and 9 g (0.3 oz) in weight.
This incremental growth may seem modest, but it reflects critical organ maturation. The brain’s surface area expands dramatically, and the lungs continue forming alveolar sacs. The modest increase in size also demonstrates the efficiency of the placenta in delivering nutrients and oxygen.
23 weeks fetal size vs 24 weeks growth
Between weeks 23 and 24, the fetus typically adds another 1.5 cm (0.6 in) in length and 15 g (0.5 oz) in weight. The jump from 23 to 24 weeks is often more noticeable on the ultrasound because the limbs start to straighten and the baby’s head becomes more proportionate.
Understanding these week‑to‑week changes helps you track whether your baby’s growth trajectory aligns with expectations. A consistent upward trend, even if each weekly measurement is slightly low, is usually reassuring.
How to interpret 23 week ultrasound size measurements
When you receive your 23‑week ultrasound report, you’ll see several key numbers:
BPD (Biparietal Diameter): Usually 6.5 cm.
HC (Head Circumference): Around 22 cm.
AC (Abdominal Circumference): Approximately 21 cm.
FL (Femur Length): About 3.5 cm.
EFW (Estimated Fetal Weight): Roughly 57 g (2 oz).
These values are plotted on growth charts. If the plotted point lands between the 10th and 90th percentile lines, the size is considered appropriate for gestational age. A point below the 10th percentile may indicate intra‑uterine growth restriction (IUGR), while above the 90th percentile could suggest macrosomia.
Providers also assess the amniotic fluid volume and placental location. A normal amniotic fluid index (AFI) and a well‑positioned placenta support healthy growth. Any concerns will typically lead to a follow‑up scan in 2‑4 weeks to confirm trends.
From our medical team: A 23‑week ultrasound is a milestone that gives a clear picture of growth and development. If your baby’s measurements are within the standard ranges, you’re on track. Remember that slight variations are normal, and the most important indicator is consistent growth over time. If anything feels off, reaching out to your provider early can provide reassurance and, if needed, a plan for closer monitoring.
What to expect during a 23‑week anatomy scan
The anatomy scan, usually performed between 20 and 24 weeks, is a comprehensive look at the baby’s organs and structures. At 23 weeks, the sonographer will focus on confirming the heart’s four chambers, checking the spine for curvature, and verifying the development of the kidneys, bladder, and lungs. The scan also assesses the placenta’s position and the amount of amniotic fluid.
According to the NHS and ACOG, a detailed anatomy scan at this stage should show a fully formed brain, visible eyes, and the beginnings of the gastrointestinal tract. Any major anomalies are rare, but the scan can detect issues such as spina bifida or heart defects early enough for planning appropriate care.
Preparing for the scan
Drink plenty of water an hour before the appointment to fill the uterus with fluid, which improves image quality. Wear comfortable clothing and avoid heavy meals that might cause discomfort. Bring a list of questions—common concerns include “Is the placenta covering the cervix?” and “Are the baby’s limbs developing normally?”
Nutrition tips to support fetal growth at 23 weeks
Nutrition remains a cornerstone of healthy fetal development. At 23 weeks, the baby’s brain and lungs are rapidly forming, so nutrients like omega‑3 fatty acids, iron, calcium, and folate are especially important. The CDC and NHS recommend at least 27 mg of iron daily and 1000 mg of calcium to support bone mineralization.
Incorporate foods such as leafy greens, fortified cereals, low‑fat dairy, and fatty fish (like salmon) that are low in mercury. If you’re vegetarian or vegan, consider a prenatal vitamin that includes vitamin B12 and DHA. Staying hydrated—aim for 8‑10 glasses of water a day—helps maintain amniotic fluid volume, which is essential for cushioning the baby.
Sample snack ideas
Greek yogurt with fresh berries and a sprinkle of chia seeds.
Whole‑grain toast topped with avocado and a boiled egg.
Warm lentil soup with a side of whole‑grain crackers.
These snacks provide a balance of protein, healthy fats, and complex carbohydrates, keeping blood sugar stable and supporting steady growth.
Common concerns about fetal size: small vs. large
Parents often worry whether a “small” baby signals trouble or a “large” baby poses delivery challenges. A small measurement—below the 10th percentile—doesn’t automatically mean pathology; it may simply reflect a naturally smaller parental frame. Conversely, a large baby (above the 90th percentile) can increase the risk of shoulder dystocia during birth, but most large babies are delivered safely via planned cesarean or assisted vaginal delivery.
Both scenarios merit closer monitoring. For a small fetus, providers might schedule more frequent ultrasounds and assess Doppler blood flow to ensure adequate nutrient delivery. For a large fetus, discussions about delivery method and timing become more prominent, often guided by ACOG’s recommendations on estimated fetal weight and maternal pelvic measurements.
Myth vs. fact
Myth: “If my baby is smaller than the average at 23 weeks, something is wrong.” Fact: Size variations of up to 2 cm in length and 15 g in weight are normal. Consistent growth is the real reassurance.
Myth: “A 23‑week baby should already be able to feel pain.” Fact: Pain perception requires fully developed neural pathways, which don’t mature until the third trimester, well after week 23.
Myth: “All babies at 23 weeks weigh exactly 2 ounces.” Fact: The average weight is 2 ounces, but healthy babies can range from about 1.3 oz to 2.7 oz.
Key takeaways
At 23 weeks, the baby is about 11.5 inches (29 cm) long—roughly the size of a large mango.
Average weight is 2 ounces (57 g), with a normal range of 1.3‑2.7 oz.
Key milestones include hearing sounds, thumb‑sucking, and the start of REM sleep cycles.
Ultrasound measurements (BPD, HC, AC, FL) are used to estimate size and weight; staying within the 10th‑90th percentile is normal.
Genetics, nutrition, maternal health, and lifestyle factors can influence fetal size.
Small variations are expected—consistent growth over time is the most important sign of health.
Nutrition rich in iron, calcium, omega‑3s, and folate supports the rapid brain and lung development at this stage.
Both small and large fetal sizes require monitoring, but most outcomes are positive with proper prenatal care.
Frequently asked questions
How big is a baby at 23 weeks?
The baby measures about 11.5 inches (29 cm) from head to rump, comparable to a large mango.
What is the average weight of a 23‑week fetus?
On average, a 23‑week fetus weighs roughly 2 ounces (57 g), though healthy ranges span 1.3‑2.7 oz.
How long is a baby at 23 weeks pregnant?
Length is around 11.5 inches (29 cm), measured from crown to rump, not including the curled legs.
What can a 23‑week fetus do?
At this stage, the baby can hear sounds, make thumb‑sucking motions, and exhibit periods of REM sleep.
Is it normal for a 23‑week fetus to be this size?
Yes—if the ultrasound measurements fall within the 10th‑90th percentile, the size is considered normal.
How does the size at 23 weeks compare to previous weeks?
From week 22 to 23, the baby typically gains about 1.5 cm (0.6 in) in length and 9 g (0.3 oz) in weight, reflecting rapid growth.
Can I feel my baby’s movements at 23 weeks?
Many people begin to notice distinct kicks and rolls around 23 weeks, especially if it’s a first pregnancy. If movements feel suddenly reduced, contact your provider.
What should I ask my doctor after the 23‑week ultrasound?
Ask whether the measurements fall within the expected percentiles, how the placenta is positioned, and if any follow‑up scans are recommended to monitor growth trends.
When to call your doctor
If you notice any of the following, contact your obstetrician or midwife promptly: a sudden decrease in fetal movements, persistent severe abdominal pain, vaginal bleeding, fluid leakage, fever above 100.4 °F (38 °C), or any signs of pre‑eclampsia such as swelling and high blood pressure. This article provides general information and does not replace personalized medical advice.
References
American College of Obstetricians and Gynecologists (ACOG). “Ultrasound in Pregnancy.” Clinical Guidance, 2023.
National Institute for Health and Care Excellence (NICE). “Fetal Growth Charts.” Updated 2022.
World Health Organization (WHO). “Fetal Growth Standards.” 2021.
Centers for Disease Control and Prevention (CDC). “Pregnancy Milestones.” 2023.
Royal College of Obstetricians and Gynaecologists (RCOG). “Fetal Development.” 2022.
Mayo Clinic. “Fetal development week by week.” 2024.
National Health Service (NHS). “The anatomy scan (20‑week scan).” Updated 2023.
U.S. Food and Drug Administration (FDA). “Prenatal Vitamins: What to Look For.” 2022.
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When Shubhra Mishra was expecting her first child in 2016, she was overwhelmed by conflicting food advice — one site said yes, another said never. By the time her second baby arrived in 2019, she realized millions of mothers face the same confusion.
That sparked a five-year journey through clinical nutrition papers, cultural diets, and expert conversations — all leading to BumpBites: a calm, compassionate space where science meets everyday motherhood.
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