Week 25 · Second trimester
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Week 25 fetal development and pregnancy guide — length about 34.6cm, weight 约660g (about the size of a a turnip)

Your baby is now about 34.6cm and 约660g, about the size of a a turnip.

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

View each day of week 25 →

Week 25 fetal development milestones: length / weight / ultrasound data

Key developmental changes during week 25:

  • The lungs enter a phase of rapid maturation — the alveoli and blood-vessel network keep developing in preparation for breathing after birth.
  • In a male fetus the testicles are still near the abdominal cavity (usually beginning to descend from weeks 26-28).
  • The brain and nervous-system connection networks grow increasingly complex and brain tissue grows rapidly.
  • Grip strength increases and the baby can grasp the umbilical cord tightly.
  • The nostrils open and the baby starts to practise breathing movements (drawing in and out amniotic fluid).
  • The proportion of subcutaneous fat clearly rises, and the body gradually fills out from being wrinkled to plump.
  • More hair starts to grow and the hair colour first shows.
  • The response to sound is more obvious, and a loud noise may cause movement or a startle.
  • Auditory memory forms — the baby shows a preference for the mother’s voice and frequently-heard music from pregnancy.
  • About 34.6cm long, about the size of a turnip, weighing about 660g.
Illustration of your baby about the size of a turnip at week 25 (about 34.6cm/约660g)
Week 25 size: about the size of a a turnip
BPD (biparietal diameter)61.7mmWidth across the head; reflects brain development
AC (abdominal circumference)204.9mmAbdomen circumference; reflects nutrient absorption
FL (femur length)44.2mmThigh bone length; tracks gestational age
Ultrasound parameters at week 25: BPD 61.7 mm, AC 204.9 mm, FL 44.2 mm (median reference)
Week 25 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 25 daily development

Your baby quietly grows every day of week 25. Tap any day to see fetal development, maternal changes, and daily guidance for that day.

169Day 1Your baby’s reproductive system keeps developing — a boy’s testicles are still near the abdominal cavity and usually only begin their slow descent to the scrotum from weeks 26-28; the whole process takes about 2-3 months and is complete around birth. Though you can’t feel this tiny physiological change, every system in your baby’s body is preparing for life outside the womb. Today you can stroke your belly and say: "Getting ready to come out, are you? No rush — there are still a dozen-plus weeks to go slowly." This sentence is both a peace-giving note to yourself and a gentle promise to your baby.170Day 2Start practising left-side sleeping tonight — put a pregnancy pillow behind your back for support and tuck a pillow between your legs so your pelvis and spine stay in natural alignment. When you side-sleep, your uterus sits away from the inferior vena cava (which runs along the right of the abdomen), so placental blood flow is fuller and your baby gets more oxygen. If left-side is uncomfortable, start on the right and switch back to the left after a few days of adjusting; don’t keep yourself rigid all night — turning a few times is your body regulating itself.171Day 3Dad’s fetal-education day: tonight dad runs all 15 minutes of family time. Lean close to the partner’s belly, tell a short story in a low, warm voice, press a palm to the belly to feel the baby respond, and end with a short, slow song (tone-deaf is fine — the baby only recognises frequency and rhythm, not pitch). Do the same time and the same song every night; the voiceprint memory formed over these two weeks has a wonderful calming effect after the baby is born.172Day 4Your OGTT result is back — whether or not GDM is confirmed, it’s manageable. If normal: keep balanced split meals and post-meal walks; don’t "indulge out of relief". If GDM is confirmed: get an individualised menu from the nutrition department, split the three main meals into five or six, swap staples to whole grains and beans, eat low-GI fruit in portions, pair protein and vegetables in each meal, and add 15-20 minutes of walking after meals — the vast majority of mums reach a good blood-sugar range through lifestyle changes alone.173Day 5Sleep problems? Three causes combine: the protruding belly makes turning hard, the bladder is squeezed causing more night urination, and leg cramps and back pain stack up. Try this bedtime routine tonight: soak your feet (38°C) for 10 minutes → massage and stretch your legs → side-sleep with a pregnancy pillow → dim the bedside lamp and read 5 pages of a paper book (not the phone). If you wake up in the night, don’t fret and fidget in bed — get up and go to the toilet first, then come back, reposition the pillow and slowly side-roll back in.174Day 6Remember three principles for choosing fruit: pick low-GI (strawberries, blueberries, cherries, kiwi, grapefruit, apples); each serving about a fist-sized amount (100-150g); and eat it as a snack between meals rather than right after a meal. Especially — don’t turn it into juice! After juicing, free sugar enters the blood quickly and dietary fiber is thrown away; what you drink is sugar water without the "protective net". The best way to eat fruit is whole and chewed.175Day 7Make a quinoa vegetable salad as your lunch staple today: boil the quinoa until done and cool, mix with lettuce, cherry tomatoes, cucumber and bell pepper, and drizzle with a little olive oil and lemon juice. Quinoa is one of the very few grains with all nine essential amino acids — its protein quality approaches that of eggs and its GI is very low, so it suits both sugar-controlled and normal mums. If raw vegetables upset your gut, blanch them before tossing and a lukewarm salad is just as good.

Week 25 belly changes

Illustration of belly changes at week 25: uterine position and abdominal prominence

At week 25 (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 25 maternal body changes and common symptoms

  • The uterine fundus is about 5cm above the navel.
  • Cumulative weight gain is about 7-10kg.
  • Sleep difficulty may start (growing belly, frequent urination, trouble turning over, leg cramps).
  • Fetal movements are strong and forceful.
  • Haemorrhoids may appear (from uterine pressure, constipation and increased pelvic blood flow).
  • Swelling of the hands and feet and lower-back pain may worsen.
  • Itchy skin and stretch marks may become more obvious.
  • The breasts enlarge and colostrum is secreted.

Week 25 nutrition advice and recommended recipes

Once the OGTT is done, keep a healthy balanced diet whatever the result; if GDM is confirmed, adjust your diet structure, split meals and monitor blood sugar under nutrition-department guidance — don’t blindly cut food on your own. Everyday sugar control: mix coarse and fine grains in staples, cut sugary drinks, choose low-GI fruit (strawberries, blueberries, cherries, kiwi) about 200-350g a day eaten in portions, and walk after meals. Daily targets: quality protein about 70g, calcium 1000mg, iron 27mg, DHA 200-300mg, fiber 25-30g, iodine 230μg, about 340 extra kcal. Avoid alcohol, raw or unpasteurised milk products, high-mercury fish, caffeine ≤200mg a day.

DHA200-300mgBrain & vision development
Recommended recipeQuinoa vegetable salad

Quinoa is a low-GI grain with complete protein; mixed with colourful vegetables, olive oil and lemon juice, it’s high-fiber, sugar-friendly and refreshing — good for GDM or weight management. Wash the vegetables thoroughly and use fresh ones; if your gut is sensitive, blanch the vegetables first and then toss.

Week 25 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 let dad take part more: dad can lean close to the belly at a set time to tell stories, sing and gently stroke it — after birth babies are often easier to soothe with the father’s voice they heard repeatedly in pregnancy, and this is a good way to build familiarity. But don’t treat fetal education as a "task" or "training"; the couple relaxing and looking forward to the baby together is itself the most valuable thing. Also choose soothing music or white noise at a volume ≤60 decibels for 15-20 minutes a day to help yourself relax.

Week 25 partner's role

①"Dad’s fetal-education day": you run all the fetal education — tell stories, sing, gently stroke the belly for 5-10 minutes so the baby learns your voice. ②Help your partner sleep better: from week 25 recommend side-lying (left side is best), prepare a pregnancy pillow and you help soak her feet before bed. ③Keep preparing iron-rich, high-protein meals to help her prevent anaemia. ④If your partner is diagnosed with GDM, learn sugar-control diet with her, eat healthy meals together, and walk after meals to ease her psychological pressure.

Week 25 checkup reminders

After the OGTT result: if normal, keep a healthy diet and regular prenatal visits; if GDM is confirmed, manage diet under nutrition-department guidance per your doctor plus monitor blood sugar daily (fasting and post-meal), use insulin if necessary — poor control raises the risks of a large baby, newborn hypoglycaemia and birth injury. After week 28, prenatal visits change from monthly to every two weeks; arrange time ahead, and you can book the 30-32-week anomaly-late-scan (small scan) ultrasound.

Week 25 key concerns

Follow up on the OGTT resultLeft-side sleeping to improve sleepGDM diet management (if confirmed)Relieve haemorrhoids/constipation30 minutes of moderate exercise daily (ACOG recommends 150 minutes a week across pregnancy)

Signs that need immediate care at week 25

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); 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. If GDM is confirmed, persistently high blood sugar or clear excessive thirst and frequent urination also need prompt contact with your doctor.

Week 25 frequently asked questions

Must I only sleep on my left side in pregnancy?
Left-side sleeping reduces pressure of the uterus on the inferior vena cava and improves placental blood flow, so it’s the recommended position. But you don’t have to force staying that way all night — turning onto your right after falling asleep is fine; comfort and good sleep matter. The main thing to avoid is prolonged lying on your back (the growing uterus presses the great vessels, which can cause supine hypotensive syndrome with dizziness).
Do I need to start counting fetal movements at week 25?
Systematic counting usually starts at week 28. At week 25 you can first become familiar with your baby’s active routine, feeling at set times each day (such as after meals and before bed) whether the baby is active, without strict counting. If you feel a clear reduction in movement, seek care any time.
How should I eat after a GDM diagnosis?
The core is "control total amounts, split meals, mix coarse and fine, cut refined sugar": 3 main meals plus 2-3 snacks a day at seven-or-eight-percent fullness; replace part of refined rice and noodles in staples with whole grains and beans; cut sugary drinks, choose low-GI fruit eaten in portions; pair protein and vegetables in each meal and walk after meals. Your specific menu is set by the nutrition department based on your blood sugar and weight.
Does GDM always require insulin?
Not necessarily. Most GDM is well controlled through diet management + exercise + blood-sugar monitoring; only when blood sugar stays above range after diet and exercise will the doctor add insulin (which is safe in pregnancy and not addictive). Whether medication is used depends on blood sugar — follow your doctor.
What if I sleep poorly at week 25?
A growing belly, frequent urination and trouble turning over all affect sleep. Use a pregnancy pillow to support your lower back, belly and legs, sleep on your left side, soak your feet before bed to relax, reduce evening fluids to cut night urination, and exercise moderately during the day. Avoid screens before bed and caffeinated drinks.
What about haemorrhoids at week 25?
Uterine pressure, constipation and increased pelvic blood flow easily cause haemorrhoids. Eat more fiber-rich vegetables and fruit, drink 1.5-2L of water daily, walk after meals, toilet regularly without squatting long; soak in warm water if they flare up. For severe bleeding or pain, see a colorectal doctor and use a pregnancy-safe topical medication — don’t self-medicate.
How do I read the week-25 ultrasound report?
The three measurements at 25 weeks: BPD (biparietal diameter) about 61.7mm, AC (abdominal circumference) about 204.9mm, and FL (femur length) about 44.2mm, 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 25?
For a standard BMI, about 0.4-0.5kg a week in the second trimester, with a cumulative gain of roughly 7-10kg by week 25 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.
What should I do about anaemia at week 25?
Dilutional anaemia is common in the second and third trimesters. Food first: red meat, animal liver (≤50g a week), spinach with vitamin C; when the prenatal visit confirms iron-deficiency anaemia, the doctor prescribes iron, taken separate from calcium, milk, strong tea and coffee for better absorption.
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. Walking after meals especially helps sugar control with GDM. 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 25?
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.
How do I relieve lower-back pain at week 25?
Forward-shifting centre of gravity and ligament relaxation cause common lower-back pain. Avoid long standing or sitting, wear supportive low-heeled shoes, side-sleep with a pregnancy pillow between the legs, do prenatal yoga and pelvic-floor exercise, and apply local warmth. Sharp pain on one side or with bleeding and fever needs care.
What about leg cramps at week 25?
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 25?
Avoid raw or undercooked meat, fish and eggs, high-mercury large fish, unpasteurised dairy, alcohol, caffeine over 200mg a day, and excess animal liver. If you have GDM, strictly control refined sugar and sugary drinks as well.
How should I choose fruit at week 25 (for sugar control)?
Choose low-GI fruit: strawberries, blueberries, cherries, kiwi, grapefruit, apples, etc., about 200-350g a day eaten in 2-3 portions between meals, avoiding juice and overeating at once. Eat less high-sugar lychee, longan, durian and watermelon (especially if you have GDM).
Is more discharge at week 25 normal?
Higher oestrogen increases white discharge; milky-white or clear and odourless is normal. Watch for turning yellow-green, foul-smelling, with itching (infection), or a sudden large amount of watery leakage (rupture of membranes) — seek care the moment these appear. Wear cotton underwear and don’t douche.
What about constipation at week 25?
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. Iron supplements can worsen constipation — discuss an adjustment with your doctor; in serious cases choose a pregnancy-safe laxative rather than buying a stimulant laxative yourself.
⚡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 25 daily focus

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

Day 1Your baby’s reproductive system keeps developing — a boy’s testicles are still near the abdominal cavity and usually only begin their slow descent to the scrotum from weeks 26-28; the whole process takes about 2-3 months and is complete around birth. Though you can’t feel this tiny physiological change, every system in your baby’s body is preparing for life outside the womb. Today you can stroke your belly and say: "Getting ready to come out, are you? No rush — there are still a dozen-plus weeks to go slowly." This sentence is both a peace-giving note to yourself and a gentle promise to your baby.Day 2Start practising left-side sleeping tonight — put a pregnancy pillow behind your back for support and tuck a pillow between your legs so your pelvis and spine stay in natural alignment. When you side-sleep, your uterus sits away from the inferior vena cava (which runs along the right of the abdomen), so placental blood flow is fuller and your baby gets more oxygen. If left-side is uncomfortable, start on the right and switch back to the left after a few days of adjusting; don’t keep yourself rigid all night — turning a few times is your body regulating itself.Day 3Dad’s fetal-education day: tonight dad runs all 15 minutes of family time. Lean close to the partner’s belly, tell a short story in a low, warm voice, press a palm to the belly to feel the baby respond, and end with a short, slow song (tone-deaf is fine — the baby only recognises frequency and rhythm, not pitch). Do the same time and the same song every night; the voiceprint memory formed over these two weeks has a wonderful calming effect after the baby is born.Day 4Your OGTT result is back — whether or not GDM is confirmed, it’s manageable. If normal: keep balanced split meals and post-meal walks; don’t "indulge out of relief". If GDM is confirmed: get an individualised menu from the nutrition department, split the three main meals into five or six, swap staples to whole grains and beans, eat low-GI fruit in portions, pair protein and vegetables in each meal, and add 15-20 minutes of walking after meals — the vast majority of mums reach a good blood-sugar range through lifestyle changes alone.Day 5Sleep problems? Three causes combine: the protruding belly makes turning hard, the bladder is squeezed causing more night urination, and leg cramps and back pain stack up. Try this bedtime routine tonight: soak your feet (38°C) for 10 minutes → massage and stretch your legs → side-sleep with a pregnancy pillow → dim the bedside lamp and read 5 pages of a paper book (not the phone). If you wake up in the night, don’t fret and fidget in bed — get up and go to the toilet first, then come back, reposition the pillow and slowly side-roll back in.Day 6Remember three principles for choosing fruit: pick low-GI (strawberries, blueberries, cherries, kiwi, grapefruit, apples); each serving about a fist-sized amount (100-150g); and eat it as a snack between meals rather than right after a meal. Especially — don’t turn it into juice! After juicing, free sugar enters the blood quickly and dietary fiber is thrown away; what you drink is sugar water without the "protective net". The best way to eat fruit is whole and chewed.Day 7Make a quinoa vegetable salad as your lunch staple today: boil the quinoa until done and cool, mix with lettuce, cherry tomatoes, cucumber and bell pepper, and drizzle with a little olive oil and lemon juice. Quinoa is one of the very few grains with all nine essential amino acids — its protein quality approaches that of eggs and its GI is very low, so it suits both sugar-controlled and normal mums. If raw vegetables upset your gut, blanch them before tossing and a lukewarm salad is just as good.

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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