Week 24 · Second trimester
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Week 24 fetal development and pregnancy guide — length about 30.0cm, weight 约600g (about the size of a an ear of corn)

Your baby is now about 30.0cm and 约600g, about the size of a an ear of corn.

Medical references: WHO INTERGROWTH-21st · China Prenatal & Pregnancy Care Guide · ACOG

View each day of week 24 →

Week 24 fetal development milestones: length / weight / ultrasound data

Key developmental changes during week 24:

  • The lungs keep producing surfactant and the bronchial tree develops further — if born now, survival under NICU care is possible (the survival rate varies a lot by region and hospital care level; some hospitals report around 50% or so, and it rises quickly with each passing week).
  • The skin is still thin and translucent, with subcutaneous vessels visible and the vernix caseosa gradually thickening.
  • The brain develops rapidly — the sulci and gyri begin to form and the neural connections proliferate.
  • The olfactory system develops, so the baby can smell changes in the amniotic fluid.
  • The inner ear is basically fully formed, and the baby is more sensitive to sound, growing calmer to familiar voices (mum’s).
  • Unique palm lines appear on the palms and the fingerprints are already formed.
  • The number of alveoli surges and the alveolar walls grow thinner, so the lung reserve moves closer to the ability to breathe on its own.
  • The muscles and bones keep getting stronger and the fetal movements are more forceful.
  • The eyes become more sensitive to light, and the baby can sense brightness and darkness through the abdominal wall.
  • About 30.0cm long, about the size of a corn cob, weighing about 600g.
Illustration of your baby about the size of an ear of corn at week 24 (about 30.0cm/约600g)
Week 24 size: about the size of a an ear of corn
BPD (biparietal diameter)58.6mmWidth across the head; reflects brain development
AC (abdominal circumference)194.3mmAbdomen circumference; reflects nutrient absorption
FL (femur length)41.7mmThigh bone length; tracks gestational age
Ultrasound parameters at week 24: BPD 58.6 mm, AC 194.3 mm, FL 41.7 mm (median reference)
Week 24 three core ultrasound parameters (median; varies by individual)

* Values are medians from WHO/China standards; individual variation is normal. References: WHO INTERGROWTH-21st, China Prenatal & Pregnancy Care Guide, ACOG guidelines.

Week 24 daily development

Your baby quietly grows every day of week 24. Tap any day to see fetal development, maternal changes, and daily guidance for that day.

162Day 1Week 24 is a milestone — if your baby were born now, under active care at a hospital with a NICU there is already a chance of survival (the rate varies a lot by region and hospital care level, and rises quickly each week). You can turn this awareness into inner steadiness: every extra week you keep going, the more mature your baby’s organs grow. Today keep eating a balanced diet and regular prenatal visits — every extra week is one more safety line.163Day 2The OGTT (oral glucose tolerance test) is this week or next — are you ready? For the three days before, eat normally and neither cut carbohydrates and sweets nor "binge" — that’s how you get a true result. Fast after 8pm the night before but you can drink a little plain water; arrive fasting in loose comfortable clothes, and bring a book or headphones to pass the roughly 2-3 hours. After the test eat the healthy snack you brought (wholewheat bread + milk), and don’t drive hungry.164Day 3Light-headed, tired, pale recently? The dilutional anaemia from rising blood volume is common in the second and third trimesters. Red meat and animal liver (≤50g a week) are the most absorbable iron sources; today choose "lean beef with green pepper" — the beef provides haem iron and the vitamin C in the pepper doubles iron absorption. If anaemia is confirmed, take the iron your doctor prescribes at least 2 hours apart from calcium and milk.165Day 4When you crave something sweet, eat steamed sweet potato — wash a fresh sweet potato with skin on, steam for 20 minutes, and it’s done when a chopstick pokes through easily. The sweet, soft flesh satisfies the sugar craving, is rich in dietary fiber to help prevent pregnancy constipation, and has a moderate GI that doesn’t spike blood sugar sharply. Portion control matters: about a fist-sized amount per serving is enough; don’t treat the sweet potato as an unlimited "healthy snack".166Day 5Your baby’s hearing is already established. Today pick a familiar poem or nursery rhyme and read it aloud in a slow, emotional tone for 3-5 minutes. Your reading’s rhythm and tone travel through bone conduction into the amniotic fluid; it won’t "teach" the baby anything, but it’s your gentlest way to connect with your child. Read the same content again at the same fixed time each day — after birth, this familiar voice may have a soothing effect.167Day 6Start the hospital-bag list in three categories: mum (maternity pads, nursing bra, disposable underwear, maternity sanitary pads, toiletries), baby (NB nappies, swaddle, one-piece outfit, wipes), documents (ID card, social-security card, prenatal records). Set up a "hospital bag" memo on your phone and tick off each item as you prepare it — roughly all in place by week 30 and packed and locked by week 36, so you go into labour calmly without any panic.168Day 7Today’s exercise goal: about 30 minutes of low-intensity activity in total. Split it — walk 15 minutes after breakfast plus 15 minutes of prenatal yoga in the afternoon, or walk 20 minutes at noon plus a slow 10-minute walk after dinner. The key is splitting the goal; don’t exercise all at once until you sweat and fatigue. Reaching the total time is enough — you don’t need to push through half an hour in one go. The point of second-trimester exercise is staying energetic, not "building muscle".

Week 24 belly changes

Illustration of belly changes at week 24: uterine position and abdominal prominence

At week 24 (second trimester) the uterus rises from the pelvis into the abdomen and most mums start to "show" — a gentle bump. First-time mums usually show a little later than mums who've been pregnant before; the fundal height sits between the navel and pubic bone.

Week 24 maternal body changes and common symptoms

  • The uterine fundus is about 4cm above the navel.
  • Cumulative weight gain is about 6-9kg (about 0.4-0.5kg a week in the second trimester for a standard BMI).
  • Symptoms of anaemia may appear (dizziness, fatigue, pale complexion) — the dilutional anaemia from rising blood volume is common in the second and third trimesters.
  • Fetal movements are strong and regular.
  • Swelling of the hands and feet and leg cramps may worsen.
  • Heartburn, bloating and constipation may appear.
  • Itchy skin (from abdominal stretching) and stretch marks may become more obvious.
  • The breasts enlarge and may secrete a little colostrum.

Week 24 nutrition advice and recommended recipes

This week comes the OGTT (oral glucose tolerance test, weeks 24-28): no need to deliberately change your diet before it — just eat normally; fast for 8-12 hours the night before and drink a little plain water. At the same time, anaemia is easy to develop in the second and third trimesters, so focus on iron: give priority to haem iron — red meat, animal liver (≤50g a week) — paired with vitamin C produce to improve absorption. Daily targets: iron 27mg, calcium 1000mg, DHA 200-300mg, fiber 25-30g, quality protein about 70g, iodine 230μg, about 340 extra kcal (ACOG). Avoid alcohol, raw or unpasteurised milk products, high-mercury fish, keep caffeine to ≤200mg a day, and don’t take iron with strong tea or coffee (tannins interfere with iron absorption).

DHA200-300mgBrain & vision development
Recommended recipeSteamed sweet potato

The natural sweetness satisfies sugar cravings, and sweet potato has a moderate GI, is rich in dietary fiber and β-carotene, filling and helps prevent constipation. If your blood sugar runs high, control the portion and use it to replace part of your rice and noodles as a staple — don’t eat too much at once.

Week 24 prenatal education guide

The core of "fetal education" is still to help the mother-to-be relax and go with the flow; there is no strong evidence that any specific stimulation makes the baby smarter. This week the baby’s hearing is more sensitive, and many mums like to read nursery rhymes and Tang poems to their baby — reading aloud in a slow, clear, rhythmic tone is a great way to relax and connect, and after birth the baby may also be calmer and more settled with sounds and rhythms heard repeatedly, but this is more about building familiarity than "teaching language early". What you can do: read aloud gently or talk 5-10 minutes at a fixed time daily; choose soothing music or white noise to relax; combine with gentle belly stroking. Enjoy the process — don’t chase "results".

Week 24 partner's role

①The OGTT needs fasting, takes about 2-3 hours with several blood draws, so it’s best for dad to accompany and bring a healthy small snack for mum to refuel right after the draw. ②Help her boost iron to prevent anaemia: prepare iron-rich meals such as red meat and animal liver (≤50g a week), and remind her not to take iron with strong tea or coffee. ③At a fixed time each day, lean close to the belly to read rhymes or talk to build a father’s voice your baby recognises. ④Help make the hospital-bag list and research baby products together.

Week 24 checkup reminders

Weeks 24-28: GDM glucose-tolerance test (OGTT). The flow is: fast and draw blood once → drink 75g glucose water within 5 minutes → draw blood once at 1 hour and once at 2 hours after drinking, about 2-3 hours in total. Diagnostic criteria (GDM is diagnosed if any of the following is met or exceeded): fasting ≥5.1, 1-hour ≥10.0, 2-hour ≥8.5 mmol/L. For those with a family history of diabetes, obesity, advanced age, previous GDM, or a history of a large baby, the doctor may arrange an earlier test or a repeat. Once GDM is confirmed you need to adjust your diet under the guidance of a nutrition department and monitor blood sugar.

Week 24 key concerns

Complete the OGTT glucose-tolerance testBoost iron to prevent anaemiaMoisturise skin to prevent stretch marksPrepare the hospital-bag list30 minutes of moderate exercise daily (ACOG recommends 150 minutes a week across pregnancy)

Signs that need immediate care at week 24

If any of the following occurs, contact your obstetrician or seek care promptly: ① persistent vaginal bleeding or brown discharge; ② sudden leakage of fluid from the vagina (possible premature rupture of membranes); ③ regular contractions (once every 10 minutes or more often) with lumbar heaviness/downward pressure (watch for preterm labour — after 24 weeks a preterm baby has survival value under care, so seeking care promptly is key); ④ a fever over 38℃ that does not come down; ⑤ severe headache, blurred vision or severe upper-abdominal pain (watch for preeclampsia — check blood pressure and urine protein); ⑥ itching all over, especially palms and soles with no rash (watch for ICP); ⑦ swelling, warmth or pain in one leg (watch for a clot); ⑧ clearly reduced fetal movement.

Week 24 frequently asked questions

How is the OGTT done at week 24?
After fasting for 8-12 hours, draw blood once first → drink 75g glucose water within 5 minutes → draw blood once at 1 hour and once at 2 hours after drinking, three draws in total lasting about 2-3 hours. During the gaps, rest quietly and move little; after the test you can eat something to refuel.
What OGTT blood-sugar values count as normal?
Diagnostic criteria (GDM is diagnosed if any is met or exceeded): fasting ≥5.1 mmol/L, 1-hour ≥10.0 mmol/L, 2-hour ≥8.5 mmol/L. If all three are below these, it’s normal. Once GDM is confirmed you adjust your diet under nutrition-department guidance and monitor blood sugar; most cases are well controlled through diet and exercise.
Do I need to fast for OGTT and can I eat normally the day before?
Yes, you need to fast (no eating for 8-12 hours the night before; a little plain water is fine). Eat normally for the 3 days before — don’t deliberately restrict food or binge on carbohydrates, or it may affect the result. Arrive at the hospital fasting that morning, and bring water and a small snack for after the test.
What should I do if I’m diagnosed with gestational diabetes (GDM)?
Don’t over-anxietise. Most GDM is well controlled through diet management guided by a nutrition department (split meals, control refined sugar, mix coarse and fine grains) plus moderate exercise and daily blood-sugar monitoring; a few need insulin under a doctor’s guidance. Good control greatly lowers the risks of a large baby and newborn hypoglycaemia.
Can a baby born at week 24 survive?
Week 24 is considered the "viability" threshold; under active NICU care the survival rate varies greatly by region and hospital care level (different studies report anywhere from very low to above half), and each extra week clearly raises survival (for week 25 different studies report roughly a third to over two-thirds). Ask your hospital’s neonatology department to assess the specific outlook. Preterm babies still have high complication risks, so keeping the pregnancy to term is best for the baby — seek care promptly at any preterm-labour sign.
What should I do about anaemia at week 24?
Blood volume rises in the second and third trimesters, so dilutional anaemia is common. Food first: red meat, animal liver (≤50g a week), spinach with vitamin C; if the prenatal visit confirms iron-deficiency anaemia, the doctor prescribes iron, and taking it separate from calcium, milk, strong tea and coffee improves absorption — don’t take large doses on your own.
How do I read the week-24 ultrasound report?
The three measurements at 24 weeks: BPD (biparietal diameter) about 58.6mm, AC (abdominal circumference) about 194.3mm, and FL (femur length) about 41.7mm, reflecting head, abdomen and leg development. If the three are in step, growth is good; a single slight deviation isn’t necessarily abnormal — go by your obstetrician’s overall assessment.
How much weight gain is normal at week 24?
For a standard BMI, about 0.4-0.5kg a week in the second trimester, with a cumulative gain of roughly 6-9kg by week 24 being common. Watch the overall trend — use a weight-gain calculator to manage by BMI — and discuss with the doctor if it’s too fast or too slow.
When should I start preparing the hospital bag?
You can start making a list in batches from week 24 and buy slowly, basically having it ready before week 34. The bag sorts into three: mum’s supplies (maternity pads, nursing bra, toiletries), baby’s supplies (NB nappies, swaddle, going-home outfit), and documents (ID card, social-security card, prenatal records).
Is there a recommended exercise duration in pregnancy?
ACOG advises women without complications about 150 minutes of moderate-intensity exercise accumulated weekly (walking, prenatal yoga, swimming), split over 5 days at about 30 minutes a day. Avoid intense exercise and pressure on the abdomen; stop and seek care for pain or bleeding.
Should I get the flu vaccine in pregnancy?
It’s recommended. The CDC and ACOG recommend that pregnant women receive the inactivated flu vaccine: pregnant women are at higher risk of severe flu, the vaccine protects mother and baby, and it is safe at every stage. During flu season (September to April) you can get vaccinated; tell them you’re pregnant.
Can I have sex at week 24?
If there’s no placenta praevia, bleeding, cervical insufficiency or threatened preterm labour, gentle sex is fine using positions that don’t press on the belly and with gentle movements. Pause if you feel unwell or the doctor advises against it; see a doctor for post-sex bleeding or pain.
What should I note about my sleeping position at week 24?
Practise sleeping on your left side to increase uterine-placental blood flow, using a pregnancy pillow to support your lower back, belly and legs; you don’t need to stay that way all night — comfort and good sleep matter; avoid prolonged lying on your back and face-down on the belly.
What about leg cramps at week 24?
When a cramp hits, flex the foot and massage the calf. Prevention: supplement calcium and magnesium, drink water, stretch before bed, wear support stockings, and avoid long standing or sitting. If cramps are frequent with weakness and numbness, check blood calcium, magnesium and electrolytes at a prenatal visit.
What should I avoid eating at week 24?
Avoid raw or undercooked meat, fish and eggs, high-mercury large fish, unpasteurised dairy, alcohol, caffeine over 200mg a day, and excess animal liver (excess vitamin A). If you have GDM, strictly control refined sugar and sugary drinks as well.
What about heartburn and bloating at week 24?
Eat smaller meals more often and chew slowly, sit or stand for 30 minutes after meals before lying down, avoid eating in the 2-3 hours before bed, and avoid spicy, greasy, overly sweet food and carbonated drinks. In serious cases, use a pregnancy-safe antacid under a doctor’s guidance.
Are the fetal movements regular at week 24?
This week movements are strong and forceful, with obvious active periods (after meals, at night). Start to notice your baby’s daily routine in preparation for formally counting movements after week 28; if one day movements clearly drop by more than half, seek care promptly.
What about constipation at week 24?
Eat more coarse grains and vegetables for dietary fiber, drink 1.5-2L of water daily, walk after meals, and toilet on a regular schedule without squatting long. In serious cases consult a doctor about a pregnancy-safe laxative rather than buying a stimulant laxative yourself; iron supplements can worsen constipation — discuss an adjustment with your doctor.
⚡The gestational-development data on this tool is compiled from the WHO INTERGROWTH-21st fetal growth standards, ACOG (American College of Obstetricians and Gynecologists), and the Chinese Medical Association's Guidelines for Pre-conception and Prenatal Care, and is reviewed for consistency by obstetrics consultants against those authoritative standards. Daily developmental tips, maternal changes, and nutrition advice follow an evidence-based approach. Note that fetal length is measured differently by week: crown–rump length (CRL) at or before week 20, and crown–heel length (CHL) from week 21 — values either side of week 21 are not directly comparable, which is a normal measurement change.

Data sources & notes

This tool provides algorithm-based estimates from the authoritative standards above for pregnancy time planning and general reference. It does not replace a doctor's diagnosis or individualized medical advice; follow your obstetrician for all prenatal care decisions.

Week 24 daily focus

Key daily tips for this week; tap any item to view the full development and guidance for that day.

Day 1Week 24 is a milestone — if your baby were born now, under active care at a hospital with a NICU there is already a chance of survival (the rate varies a lot by region and hospital care level, and rises quickly each week). You can turn this awareness into inner steadiness: every extra week you keep going, the more mature your baby’s organs grow. Today keep eating a balanced diet and regular prenatal visits — every extra week is one more safety line.Day 2The OGTT (oral glucose tolerance test) is this week or next — are you ready? For the three days before, eat normally and neither cut carbohydrates and sweets nor "binge" — that’s how you get a true result. Fast after 8pm the night before but you can drink a little plain water; arrive fasting in loose comfortable clothes, and bring a book or headphones to pass the roughly 2-3 hours. After the test eat the healthy snack you brought (wholewheat bread + milk), and don’t drive hungry.Day 3Light-headed, tired, pale recently? The dilutional anaemia from rising blood volume is common in the second and third trimesters. Red meat and animal liver (≤50g a week) are the most absorbable iron sources; today choose "lean beef with green pepper" — the beef provides haem iron and the vitamin C in the pepper doubles iron absorption. If anaemia is confirmed, take the iron your doctor prescribes at least 2 hours apart from calcium and milk.Day 4When you crave something sweet, eat steamed sweet potato — wash a fresh sweet potato with skin on, steam for 20 minutes, and it’s done when a chopstick pokes through easily. The sweet, soft flesh satisfies the sugar craving, is rich in dietary fiber to help prevent pregnancy constipation, and has a moderate GI that doesn’t spike blood sugar sharply. Portion control matters: about a fist-sized amount per serving is enough; don’t treat the sweet potato as an unlimited "healthy snack".Day 5Your baby’s hearing is already established. Today pick a familiar poem or nursery rhyme and read it aloud in a slow, emotional tone for 3-5 minutes. Your reading’s rhythm and tone travel through bone conduction into the amniotic fluid; it won’t "teach" the baby anything, but it’s your gentlest way to connect with your child. Read the same content again at the same fixed time each day — after birth, this familiar voice may have a soothing effect.Day 6Start the hospital-bag list in three categories: mum (maternity pads, nursing bra, disposable underwear, maternity sanitary pads, toiletries), baby (NB nappies, swaddle, one-piece outfit, wipes), documents (ID card, social-security card, prenatal records). Set up a "hospital bag" memo on your phone and tick off each item as you prepare it — roughly all in place by week 30 and packed and locked by week 36, so you go into labour calmly without any panic.Day 7Today’s exercise goal: about 30 minutes of low-intensity activity in total. Split it — walk 15 minutes after breakfast plus 15 minutes of prenatal yoga in the afternoon, or walk 20 minutes at noon plus a slow 10-minute walk after dinner. The key is splitting the goal; don’t exercise all at once until you sweat and fatigue. Reaching the total time is enough — you don’t need to push through half an hour in one go. The point of second-trimester exercise is staying energetic, not "building muscle".

Content sources & notes

This guide references WHO INTERGROWTH-21st standards, the China Prenatal & Pregnancy Care Guide, ACOG clinical guidelines and BabyCenter (medically reviewed).

This page is educational pregnancy information for general reference and does not replace the diagnosis or advice of a licensed healthcare provider.

View the full fetal BPD/AC/FL reference table (weeks 14–42) →

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