Week 34 · Third trimester
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Week 34 fetal development and pregnancy guide — length about 45.0cm, weight 约2146g (about the size of a a cantaloupe)

Your baby is now about 45.0cm and 约2146g, about the size of a a cantaloupe.

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

View each day of week 34 →

Week 34 fetal development milestones: length / weight / ultrasound data

Key developmental changes during week 34:

  • The lungs are basically mature, and a baby born after 34 weeks can usually breathe on its own.
  • The central nervous system is mature enough to control body temperature well.
  • The brown-fat layer thickens, storing energy to maintain body temperature after birth.
  • Immune protection is fairly complete and can cope with most common pathogens.
  • Subcutaneous fat is ample and the body appears round and proportionate.
  • The hypothalamic thermoregulation centre matures, maintaining body temperature and rhythmic breathing well.
  • Hearing is keen, able to distinguish pitch and emotion.
  • Fetal movement is regular with obvious active windows.
  • The nails fully cover the fingertips.
  • The vast majority of babies have their position fixed head-down.
  • About 45.0cm long, about the size of a Hami melon, weighing about 2146g.
Illustration of your baby about the size of a cantaloupe at week 34 (about 45.0cm/约2146g)
Week 34 size: about the size of a a cantaloupe
BPD (biparietal diameter)85mmWidth across the head; reflects brain development
AC (abdominal circumference)299.3mmAbdomen circumference; reflects nutrient absorption
FL (femur length)63.2mmThigh bone length; tracks gestational age
Ultrasound parameters at week 34: BPD 85 mm, AC 299.3 mm, FL 63.2 mm (median reference)
Week 34 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 34 daily development

Your baby quietly grows every day of week 34. Tap any day to see fetal development, maternal changes, and daily guidance for that day.

232Day 1Your baby’s lungs reach "basically mature" status today — this means even if born now, it can most likely breathe on its own without a ventilator (some 34-week babies may need brief monitoring or assisted ventilation, but the risk of severe respiratory distress is already low). This is one of the most important third-trimester safety milestones — from today your baby is just one breath away from moving from "fetus" to "newborn".233Day 2Eat garlic broccoli today — blanch the broccoli for 30 seconds (quickly removing raw flavour while keeping the green and nutrients; vitamin K is fat-soluble and survives blanching), stir-fry minced garlic until fragrant, then quickly toss the broccoli for 1 minute. Deep-green leafy vegetables and cruciferous vegetables like broccoli are rich in vitamin K, crucial for clotting-factor synthesis. Note: newborn haemorrhagic disease is mainly prevented by the routine vitamin-K injection after birth; maternal food helps but cannot replace it.234Day 3Have your first NST (fetal-heart monitoring) today — two elastic bands are placed on your belly (one monitoring the fetal heart, one monitoring contractions), you hold a button to press whenever you feel fetal movement, and the machine draws two curves of heart-rate changes and contraction strength, about 20-40 minutes in total. The normal result is "reactive": within 20 minutes there are 2+ accelerations (≥15 bpm, lasting ≥15 seconds) of the fetal heart rate with fetal movement.235Day 4Open the hospital bag for the last round of "practical checking": mum’s supplies — maternity pads, nursing bra, disposable underwear, extra-long night pads, travel toiletries; baby’s supplies — 30 NB nappies, swaddle, going-home wrap suit, small hat; documents — ID card, social-security card, prenatal records, a few hundred yuan cash. Tick off each item in a photo checklist, and send a "final hospital bag" photo to the family group chat.236Day 5Before bed, a gentle conversation: "Baby, your mum’s lungs have breathed for you for 34 weeks; from this week your little lungs can also work on their own. We’re ready to see you — pick a good day to come out." This isn’t inducing labour; it’s a psychological nudge for yourself and your baby — telling your subconscious and its inner clock: everything is mature; time to wait for the final natural signal.237Day 6Check the cot’s safety details: rail spacing no more than 6cm (to keep the head from getting stuck), the mattress snug against the frame with no gaps, the bed holding only a fitted sheet with no pillows, quilts or plush toys (lowering the risk of sudden infant death syndrome, SIDS), and the bed away from windows and curtain cords. You don’t need the most expensive cot, but safety details must not be missed — where a baby sleeps 14-17 hours a day, safety is the absolute baseline.238Day 7From today, if regular contractions appear (once every 10 minutes or more, growing more frequent and stronger), go to the hospital immediately whether or not you’re full term — after 34 weeks contraction suppressors are generally no longer used routinely and it’s handled by the natural-delivery protocol. Be clear about this policy shift: your task isn’t "don’t go out and wait for the due date", but "set off as soon as contractions are regular".

Week 34 belly changes

Illustration of belly changes at week 34: uterine position and abdominal prominence

At week 34 (third trimester) the uterine fundus keeps rising closer to the sternum. Your belly is clearly rounded and your waistline and fundal height grow quickly, so pay more attention to balance and safety in daily movement.

Week 34 maternal body changes and common symptoms

  • The uterine fundus reaches its highest point, about 14cm above the navel.
  • Cumulative weight gain is about 11-15kg (about 0.4-0.5kg a week in the third trimester for a standard BMI).
  • Movement is more inconvenient and the lumbar load is at its peak.
  • Bloating, heartburn and constipation may persist.
  • Leg swelling, cramps and varicose veins may become more obvious.
  • Sleep difficulty and lower-back or pubic-bone pain may worsen.
  • Itchy abdominal skin, stretch marks and urine leaking.
  • The breasts enlarge, colostrum is secreted, and Braxton Hicks false contractions are frequent.

Week 34 nutrition advice and recommended recipes

This week you can ensure vitamin-K intake (dark leafy greens, broccoli, natto, etc.), but the prevention of newborn haemorrhagic disease mainly relies on the routine vitamin-K injection the doctor gives after birth, so don’t over-rely on food. Daily targets still follow authority guidance: quality protein about 80-90g, iron about 27-29mg, calcium 1000mg, DHA 200-300mg, fiber 25-30g, iodine 230μg. Keep controlling sugar (strict for GDM). Avoid alcohol, raw or unpasteurised milk products, high-mercury fish, caffeine ≤200mg a day.

DHA200-300mgBrain & vision development
Recommended recipeGarlic broccoli

Broccoli is rich in vitamin K, dietary fiber and vitamin C; stir-frying with garlic preserves the nutrients — a good third-trimester vegetable choice. If you have a thyroid condition, eat broccoli in moderation and cook it thoroughly; if your gut is sensitive, don’t eat it too raw.

Week 34 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 you can tell your baby in gentle words "Mum and Dad are ready, and looking forward to meeting you" — a great way to relax and connect that also relieves your own delivery tension. What you can do: talk gently 5-10 minutes at a set time daily, combined with gentle stroking; choose soothing music to relax. Understanding fetal education as "caring for mum’s mood" is the most practical.

Week 34 partner's role

①Do the final hospital-bag check: mum’s supplies + baby’s supplies + documents, ensuring it’s complete by week 34 with the list by the door. ②Review the Lamaze breathing technique and pain-relief methods with your partner, and practise alongside during labour. ③Talk or sing close to the belly at a set time daily to build a father’s voice the baby recognises. ④Help relieve swelling and prepare admission items (phone power bank, route, maternity-hospital phone number), on call at any time.

Week 34 checkup reminders

Weeks 28-36: routine visits every two weeks (weekly after 36), plus NST fetal-heart monitoring (generally every 1-2 weeks until delivery, more frequent for high-risk mums). This week you can complete the GBS screening (the 35-37-week window, though it can also be done this week). Keep counting fetal movements daily. If regular contractions appear after week 34, tocolysis is generally no longer active — it’s handled by the preterm-delivery protocol; seek care promptly.

Week 34 key concerns

Weekly NST fetal-heart monitoringEnsure vitamin-K intakeFinal hospital-bag checkReview the delivery course30 minutes of moderate exercise daily (ACOG recommends 150 minutes a week across pregnancy)

Signs that need immediate care at week 34

If any of the following occurs, contact your obstetrician or seek care promptly: ① regular contractions (5-10 minute intervals, growing more frequent and stronger) → seek care even if it isn’t the due date (after 34 weeks tocolysis is generally no longer used); ② clearly reduced fetal movement (under 10 in 2 hours or down by more than half from usual); ③ sudden vaginal leakage of fluid (possible premature rupture of membranes); ④ persistent severe headache, blurred vision or upper-abdominal pain with raised blood pressure or sudden swelling (watch for preeclampsia); ⑤ itching all over, especially palms and soles with no rash (watch for ICP); ⑥ a fever over 38℃ that does not come down; ⑦ swelling, warmth and pain in one leg or sudden breathing difficulty and chest pain (watch for a clot/pulmonary embolism); ⑧ a large amount of bright-red vaginal bleeding (watch for placenta praevia) or sudden obvious swelling.

Week 34 frequently asked questions

Does a 34-week baby need an incubator?
A 34-week baby is a late preterm infant; after birth it usually needs short-term observation in the neonatal department (breathing, temperature, blood sugar, jaundice, etc.). Once weight is normal and condition is good, rooming-in may be possible after assessment. The specific decision is made by the neonatal doctor.
Should the hospital bag be complete at week 34?
Yes. After week 34 labour can start at any time. The bag — mum’s supplies (maternity pads, nursing bra, toiletries) + baby’s supplies (NB nappies, swaddle, going-home outfit) + documents (ID card, social-security card, prenatal records) — should be complete with the list by the door so you can leave at a moment’s notice.
How much weight gain is normal at week 34?
A cumulative gain of about 11-15kg by week 34 is common. For a standard BMI, the third trimester is about 0.4-0.5kg a week and the whole pregnancy recommends about 11.5-16kg. Watch the overall trend and manage by BMI with a weight-gain calculator.
What is the NST fetal-heart monitoring at week 34?
NST (non-stress test) uses a fetal-heart monitor to see how the baby’s heart rate responds to fetal movement, assessing intrauterine wellbeing. Generally done every 1-2 weeks from week 34 until delivery, earlier and more often for high-risk mums. It takes about 20-40 minutes and is non-invasive.
How do I read the week-34 ultrasound report?
The three measurements at 34 weeks: BPD (biparietal diameter) about 85.0mm, AC (abdominal circumference) about 299.3mm, and FL (femur length) about 63.2mm. If the three are in step, growth is good; a single slight deviation isn’t necessarily abnormal — go by your obstetrician’s overall assessment.
Are the fetal movements regular at week 34?
Most babies have obvious active periods. Since week 28, count fetal movements daily: one hour in the morning, afternoon and evening each; ≥10 within 2 hours is normal. If it’s clearly under 10 in 2 hours or down by more than half from usual, seek care immediately.
What if the GBS screening is positive?
GBS (group-B streptococcus) is a common colonising bacterium and doesn’t mean infection. Intravenous antibiotics during delivery can effectively prevent about 80% of newborn infections and doesn’t affect vaginal delivery. Screening is generally arranged at weeks 35-37.
What should I note at week 34?
Priorities: weekly NST monitoring, keep counting fetal movements, routine visits, hospital bag in place, and tell true from false contractions. Seek care promptly at signals of regular contractions, broken waters, "show" or reduced movement.
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. In the third trimester focus on walking and stretching; avoid intense exercise and pressure on the abdomen; stop and seek care for pain or bleeding.
Do I still need a vaccine in the third trimester?
Yes. The CDC and ACOG recommend the Tdap whooping-cough vaccine at weeks 27-36 to prevent Pertussis in the baby; the inactivated flu vaccine can also be given in flu season. Both are pregnancy-safe vaccines; tell them you’re pregnant before vaccination.
Can I have sex at week 34?
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. The closer to term, the more caution in the third trimester; pause if unwell or the doctor advises against it; seek care for post-sex bleeding, pain or leaking fluid.
What about leg cramps and swelling at week 34?
When a cramp hits, flex the foot and massage the calf; prevention relies on supplementing calcium and magnesium, drinking water and stretching before bed. For swelling, raise your legs, lie on your left side, walk to promote return flow, and moderately limit salt. If swelling suddenly worsens, spreads to the face and hands, or comes with headache or vision changes, check blood pressure to rule out preeclampsia.
What should I avoid eating at week 34?
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.
What about heartburn and bloating at week 34?
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, avoid spicy, greasy, overly sweet food and carbonated drinks, and prop up your upper body when sleeping. In serious cases, use a pregnancy-safe antacid under a doctor’s guidance.
What about constipation and haemorrhoids at week 34?
Eat more coarse grains and vegetables for dietary fiber, drink 1.5-2L of water daily, walk after meals, and toilet regularly without squatting long; soak in warm water for haemorrhoids. Iron supplements can worsen constipation — discuss an adjustment with your doctor; in serious cases choose a pregnancy-safe medication rather than a stimulant laxative.
What about lower-back and pubic-bone pain at week 34?
It comes from a forward centre of gravity and relaxin loosening the ligaments and pelvic joints. Avoid long standing or sitting, wear supportive low-heeled shoes, use a belly-support belt, side-sleep with a pregnancy pillow, do prenatal yoga and pelvic-floor exercise, and apply local warmth. Sharp pain on one side or with bleeding and fever needs care.
What if I sleep poorly at week 34?
A growing belly, frequent urination and trouble turning over affect sleep. Use a pregnancy pillow for support, 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.
Is it normal to have many false contractions at week 34?
More frequent false contractions in the third trimester are common: brief tightening of the belly, painless and irregular, disappearing with rest. If they become regular, with pain or lumbar heaviness down, seek care to rule out preterm labour (after 34 weeks tocolysis is generally no longer used).
What should go in the hospital bag?
It sorts into three: mum’s supplies (maternity pads, nursing bra, toiletries, straw cup), baby’s supplies (NB nappies, swaddle, going-home outfit, small hat), and documents (ID card, social-security card, prenatal records). Keep it by the door so you can leave at a moment’s notice.
⚡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 34 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 lungs reach "basically mature" status today — this means even if born now, it can most likely breathe on its own without a ventilator (some 34-week babies may need brief monitoring or assisted ventilation, but the risk of severe respiratory distress is already low). This is one of the most important third-trimester safety milestones — from today your baby is just one breath away from moving from "fetus" to "newborn".Day 2Eat garlic broccoli today — blanch the broccoli for 30 seconds (quickly removing raw flavour while keeping the green and nutrients; vitamin K is fat-soluble and survives blanching), stir-fry minced garlic until fragrant, then quickly toss the broccoli for 1 minute. Deep-green leafy vegetables and cruciferous vegetables like broccoli are rich in vitamin K, crucial for clotting-factor synthesis. Note: newborn haemorrhagic disease is mainly prevented by the routine vitamin-K injection after birth; maternal food helps but cannot replace it.Day 3Have your first NST (fetal-heart monitoring) today — two elastic bands are placed on your belly (one monitoring the fetal heart, one monitoring contractions), you hold a button to press whenever you feel fetal movement, and the machine draws two curves of heart-rate changes and contraction strength, about 20-40 minutes in total. The normal result is "reactive": within 20 minutes there are 2+ accelerations (≥15 bpm, lasting ≥15 seconds) of the fetal heart rate with fetal movement.Day 4Open the hospital bag for the last round of "practical checking": mum’s supplies — maternity pads, nursing bra, disposable underwear, extra-long night pads, travel toiletries; baby’s supplies — 30 NB nappies, swaddle, going-home wrap suit, small hat; documents — ID card, social-security card, prenatal records, a few hundred yuan cash. Tick off each item in a photo checklist, and send a "final hospital bag" photo to the family group chat.Day 5Before bed, a gentle conversation: "Baby, your mum’s lungs have breathed for you for 34 weeks; from this week your little lungs can also work on their own. We’re ready to see you — pick a good day to come out." This isn’t inducing labour; it’s a psychological nudge for yourself and your baby — telling your subconscious and its inner clock: everything is mature; time to wait for the final natural signal.Day 6Check the cot’s safety details: rail spacing no more than 6cm (to keep the head from getting stuck), the mattress snug against the frame with no gaps, the bed holding only a fitted sheet with no pillows, quilts or plush toys (lowering the risk of sudden infant death syndrome, SIDS), and the bed away from windows and curtain cords. You don’t need the most expensive cot, but safety details must not be missed — where a baby sleeps 14-17 hours a day, safety is the absolute baseline.Day 7From today, if regular contractions appear (once every 10 minutes or more, growing more frequent and stronger), go to the hospital immediately whether or not you’re full term — after 34 weeks contraction suppressors are generally no longer used routinely and it’s handled by the natural-delivery protocol. Be clear about this policy shift: your task isn’t "don’t go out and wait for the due date", but "set off as soon as contractions are regular".

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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