Week 28 · Third trimester
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Week 28 fetal development and pregnancy guide — length about 37.6cm, weight 约1005g (about the size of a a large eggplant)

Your baby is now about 37.6cm and 约1005g, about the size of a a large eggplant.

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

View each day of week 28 →

Week 28 fetal development milestones: length / weight / ultrasound data

Key developmental changes during week 28:

  • The brain develops rapidly: the sulci and gyri deepen, the brain weight grows quickly (about 350-400g at birth), and the neural connections increase greatly.
  • Hearing, smell and touch are all mature and functional.
  • The central nervous system begins to regulate body temperature, manage rhythmic breathing movements and strengthen the lungs.
  • The bone marrow gradually takes over from the liver as the main blood-making organ (red blood cells are mainly produced by the bone marrow).
  • The intestines lengthen and coil within the abdominal cavity, and the digestive layout is formed.
  • The eyelashes have grown, and the baby blinks at light through the abdominal wall.
  • Fat keeps accumulating, the limbs and cheeks grow rounder, and the body proportions are more balanced.
  • Fetal movements are strong and can be seen from outside the belly; most babies gradually turn to a head-down position between weeks 28-36.
  • About 37.6cm long, about the length of a big eggplant, weighing about 1005g (already over 1kg).
Illustration of your baby about the size of a large eggplant at week 28 (about 37.6cm/约1005g)
Week 28 size: about the size of a a large eggplant
BPD (biparietal diameter)70.6mmWidth across the head; reflects brain development
AC (abdominal circumference)236.1mmAbdomen circumference; reflects nutrient absorption
FL (femur length)51.2mmThigh bone length; tracks gestational age
Ultrasound parameters at week 28: BPD 70.6 mm, AC 236.1 mm, FL 51.2 mm (median reference)
Week 28 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 28 daily development

Your baby quietly grows every day of week 28. Tap any day to see fetal development, maternal changes, and daily guidance for that day.

190Day 1You officially enter the third trimester! From today prenatal visits change from monthly to every two weeks, and set alarm reminders on your phone for two days and one day before each visit. The third trimester is the key monitoring period for gestational hypertension, preeclampsia and fetal growth restriction; the two-weekly visit frequency exists precisely to "err on the side of coming more often rather than missing a case". Save your maternity hospital’s phone number in your contacts and star it.191Day 2Today is the first day of formally counting fetal movements! Method: pick a fixed hour in the morning, afternoon and evening each day (for example 8am, 2pm and 9pm), lie on your left side or half-sit and quietly record each independent fetal movement, counting continuous movements (like three kicks in a row) as one. Generally ≥3-5 an hour or ≥10 within 2 hours is normal. If it’s under 10 in 2 hours or clearly down by more than half from usual, don’t wait at home — go straight to the hospital.192Day 3Your baby’s weight passes 1kg today! This is a landmark in the third trimester — from now your baby’s weight will grow rapidly, about 150-200g a week, reaching 3-3.5kg by week 40. Your protein and iron intake today directly determine your baby’s "high-quality growth" — quality protein builds muscle and organs, and iron gives it ample haemoglobin.193Day 4Eat a bowl of red-bean black-rice porridge: red beans help diuresis and replenish iron, black rice contains anthocyanins and iron; simmer slowly until soft and stringy and add a few walnuts for DHA. In the third trimester blood volume is near its peak, so iron replenishment is more urgent than in the middle trimester; a warm bowl of porridge is both iron-replenishing and soothing for the stomach and swelling. If blood sugar runs high, control the portion and pair it with a boiled egg to slow the rise.194Day 5Start researching perineal massage today — from week 34 you can do it 5-10 minutes daily, using vitamin E oil or a special massage oil; after washing your hands, insert your thumb about 3-4cm into the vagina and press gently in a U shape. Perineal massage can increase birth-canal elasticity and lower the risk of tearing and episiotomy — an evidence-supported pregnancy "birth-preparation" method. Ask your doctor first if you have placenta praevia or preterm-labour risk.195Day 6Dad, tonight is lesson one of the "antenatal training camp": learn the basic flow and time ranges of the three stages of labour (first stage, opening the cervix; second stage, delivering the baby; third stage, delivering the placenta). Your knowledge as a partner can give the mother-to-be the most real-time support in the labour ward — "better to know than to think you know but not really". Spend 15 minutes watching an authoritative obstetric science video and note the key time points.196Day 7Record the "baby over 1kg" milestone in your pregnancy diary and stick a B-ultrasound photo beside it (if you had one this week). Today also take a front belly photo as the first of the third trimester — the belly is already about 8cm above the navel, with the skin stretched taut. From now on take a photo every two weeks until delivery; strung together at the end it will be the most striking visual record of your whole pregnancy.

Week 28 belly changes

Illustration of belly changes at week 28: uterine position and abdominal prominence

At week 28 (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 28 maternal body changes and common symptoms

  • You enter the third trimester! Prenatal visits change from monthly to every two weeks.
  • Start counting fetal movements every day — an important way to monitor your baby’s wellbeing.
  • Fetal movements are strong and forceful — you may see the belly pushed up.
  • The uterine fundus is about 8cm above the navel.
  • Cumulative weight gain is about 8-11kg (about 0.4-0.5kg a week in the third trimester).
  • Leg swelling, varicose veins or haemorrhoids may appear.
  • Shortness of breath, heartburn and lower-back pain may worsen.
  • The breasts enlarge, colostrum is secreted, and Braxton Hicks contractions may appear.

Week 28 nutrition advice and recommended recipes

In the third trimester iron needs rise further (the Chinese Nutrition Society recommends about 29mg a day in late pregnancy, ACOG about 27mg). Prevent and correct late-pregnancy anaemia: give priority to haem iron — red meat, animal liver (≤50g a week), animal blood — paired with vitamin C produce to improve absorption; black fungus, seaweed and red beans also contain iron. Don’t take iron with strong tea, coffee or milk (tannins and calcium interfere with iron absorption). Daily targets: iron about 27-29mg, quality protein about 80-85g, calcium 1000mg, DHA 200-300mg, fiber 25-30g, iodine 230μg. Avoid alcohol, raw or unpasteurised milk products, high-mercury fish, caffeine ≤200mg a day.

DHA200-300mgBrain & vision development
Recommended recipeRed-bean black-rice porridge

Red beans replenish iron and help diuresis, and black rice supplements iron and contains anthocyanins; simmered slowly until soft and easy to digest, it suits late-pregnancy iron supplementation and helping reduce swelling. If your blood sugar runs high, control the portion and eat it with protein and nuts to slow the blood-sugar rise.

Week 28 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. In the third trimester the baby’s hearing is keen with a clear routine, so you can do a simple daily "fetal-education package" during the baby’s awake and active periods: stroke the belly 5 minutes → play soothing music 5 minutes → talk gently or read a picture book 5 minutes → deep-breathing relaxation 5 minutes, about 20 minutes in total (a torch on the belly for "light fetal education" is not recommended — no proven benefit and it may disturb the baby). The key is to be regular, gentle, and relaxing for both of you — don’t chase a "training" effect.

Week 28 partner's role

①Enter the "antenatal training camp": learn the three stages of labour and the Lamaze breathing technique with your partner, understand the procedures and indications for natural and caesarean delivery, and be ready to accompany in the labour ward. ②Count fetal movements with your partner: accompany her to quietly record at the same time slots morning, noon and evening. ③Help boost iron: prepare high-iron meals such as red meat and animal liver (≤50g a week), and remind her not to take iron with strong tea or coffee. ④Help relieve swelling: raise her legs, soak her feet in warm water and gently massage her feet.

Week 28 checkup reminders

Week 28 begins the third trimester: prenatal visits change to every two weeks. This week is a routine visit plus a full blood-count recheck (to detect late-pregnancy anaemia). Start formally counting fetal movements every day: pick one hour in the morning, afternoon and evening, record while lying on your left side or sitting; generally ≥3-5 an hour or ≥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. You can book the 30-32-week small scan. From week 34 you can start perineal massage (increasing the elasticity of the birth canal to lower the tear risk).

Week 28 key concerns

Prenatal visits every two weeksStart counting fetal movements dailyBoost iron to prevent anaemiaLearn delivery knowledge/Lamaze breathing30 minutes of moderate exercise daily (ACOG recommends 150 minutes a week across pregnancy)

Signs that need immediate care at week 28

If any of the following occurs, contact your obstetrician or seek care promptly: ① clearly reduced fetal movement (under 10 in 2 hours or down by more than half from usual); ② vaginal bleeding or leakage of fluid (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 persistent severe headache, blurred vision or upper-abdominal pain, especially with raised blood pressure or sudden obvious 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 or pain in one leg or sudden breathing difficulty and chest pain (watch for a clot/pulmonary embolism); ⑧ persistent abdominal pain or a tender uterus.

Week 28 frequently asked questions

How do I count fetal movements in the third trimester?
From week 28, pick one hour in the morning, afternoon and evening each, lie on your left side or sit quietly, and record fetal movements, counting continuous movements as one. Generally ≥3-5 an hour or ≥10 within 2 hours is normal; you can also record the time it takes to feel 10 movements. If it’s clearly under 10 in 2 hours, or down by more than half from usual, seek care immediately.
How many fetal movements count as normal, and what if they decrease?
The key is comparing to your baby’s usual pattern: a sudden clear decrease, weakness, or a long still period deserves more vigilance. If you notice fewer movements, first lie on your left side, eat a little, and quietly focus on sensing for 1-2 hours; if still clearly low or absent, go straight to the hospital for fetal-heart monitoring — don’t wait at home.
Can I do perineal massage at week 28?
It’s not recommended to start until after week 34 (now is not the time), but you can learn the method: perineal massage helps increase the elasticity of the birth canal and perineal tissue, lowering the risk of tearing and episiotomy. Then use vitamin E oil or a special massage oil, 5-10 minutes daily, with dad helping if needed. Those with placenta praevia, vaginal infection or preterm-labour risk should consult a doctor first.
What should I note on entering the third trimester at week 28?
Priorities: ① start counting fetal movements every day; ② prenatal visits change to every two weeks — do them on time; ③ keep boosting iron to prevent anaemia and control sugar (GDM); ④ book the small scan (30-32 weeks) and learn about delivery; ⑤ begin preparing the hospital bag in batches. Seek care promptly at signals of reduced movement, "show", broken waters or regular contractions.
What should I do about anaemia at week 28?
Iron needs rise in the third trimester and dilutional anaemia is common. Food first: red meat, animal liver (≤50g a week), animal blood, 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 — don’t take large doses on your own.
How do I read the week-28 ultrasound report?
The three measurements at 28 weeks: BPD (biparietal diameter) about 70.6mm, AC (abdominal circumference) about 236.1mm, and FL (femur length) about 51.2mm, 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 28?
A cumulative gain of about 8-11kg by week 28 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; discuss too-fast or too-slow gain with your doctor.
How is perineal massage done?
Wash your hands and trim your nails, take a comfortable semi-reclining position, lubricate with vitamin E oil or a special massage oil, insert your thumb about 3-4cm into the vagina and press slowly downwards and to both sides in a U-shaped massage; it should feel like a mild stretch, not pain, 5-10 minutes each time. If your partner helps, keep the movement equally gentle.
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.
Can I still get vaccines in the third trimester?
Yes. The CDC and ACOG recommend the Tdap whooping-cough vaccine at weeks 27-36 so the baby gets maternal antibody after birth to prevent Pertussis; 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 28?
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 if there’s post-sex bleeding, pain or leaking fluid.
What if I sleep poorly at week 28?
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.
What about leg cramps and swelling at week 28?
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 28?
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 at week 28?
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 28?
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 pain at week 28?
It comes from a forward centre of gravity and ligament relaxation. 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.
When should I prepare the hospital bag?
You can prepare it in batches from week 28 and basically have it ready by week 34. It 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). Keep the list 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 28 daily focus

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

Day 1You officially enter the third trimester! From today prenatal visits change from monthly to every two weeks, and set alarm reminders on your phone for two days and one day before each visit. The third trimester is the key monitoring period for gestational hypertension, preeclampsia and fetal growth restriction; the two-weekly visit frequency exists precisely to "err on the side of coming more often rather than missing a case". Save your maternity hospital’s phone number in your contacts and star it.Day 2Today is the first day of formally counting fetal movements! Method: pick a fixed hour in the morning, afternoon and evening each day (for example 8am, 2pm and 9pm), lie on your left side or half-sit and quietly record each independent fetal movement, counting continuous movements (like three kicks in a row) as one. Generally ≥3-5 an hour or ≥10 within 2 hours is normal. If it’s under 10 in 2 hours or clearly down by more than half from usual, don’t wait at home — go straight to the hospital.Day 3Your baby’s weight passes 1kg today! This is a landmark in the third trimester — from now your baby’s weight will grow rapidly, about 150-200g a week, reaching 3-3.5kg by week 40. Your protein and iron intake today directly determine your baby’s "high-quality growth" — quality protein builds muscle and organs, and iron gives it ample haemoglobin.Day 4Eat a bowl of red-bean black-rice porridge: red beans help diuresis and replenish iron, black rice contains anthocyanins and iron; simmer slowly until soft and stringy and add a few walnuts for DHA. In the third trimester blood volume is near its peak, so iron replenishment is more urgent than in the middle trimester; a warm bowl of porridge is both iron-replenishing and soothing for the stomach and swelling. If blood sugar runs high, control the portion and pair it with a boiled egg to slow the rise.Day 5Start researching perineal massage today — from week 34 you can do it 5-10 minutes daily, using vitamin E oil or a special massage oil; after washing your hands, insert your thumb about 3-4cm into the vagina and press gently in a U shape. Perineal massage can increase birth-canal elasticity and lower the risk of tearing and episiotomy — an evidence-supported pregnancy "birth-preparation" method. Ask your doctor first if you have placenta praevia or preterm-labour risk.Day 6Dad, tonight is lesson one of the "antenatal training camp": learn the basic flow and time ranges of the three stages of labour (first stage, opening the cervix; second stage, delivering the baby; third stage, delivering the placenta). Your knowledge as a partner can give the mother-to-be the most real-time support in the labour ward — "better to know than to think you know but not really". Spend 15 minutes watching an authoritative obstetric science video and note the key time points.Day 7Record the "baby over 1kg" milestone in your pregnancy diary and stick a B-ultrasound photo beside it (if you had one this week). Today also take a front belly photo as the first of the third trimester — the belly is already about 8cm above the navel, with the skin stretched taut. From now on take a photo every two weeks until delivery; strung together at the end it will be the most striking visual record of your whole pregnancy.

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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