PREGNANCY GUIDE · PART 3 OF 3

Third Trimester Guide: Weeks 29 to 40

Counting movements, how the baby is lying, telling real labour from false, and what to have packed by 36 weeks.

Reviewed by Dr. Grishma Ranjangaonkar, MBBS, DGO, ICOG Fellowship in Gynecological Endoscopy · Eva WomanCare Clinic, Vashi

Almost nothing new is built in the last twelve weeks. What happens is growth, lung maturation and fat, while appointments get closer together because the problems worth catching late in pregnancy develop fast. This guide covers the part that matters most: knowing what to act on.

Where the third trimester sits in the forty weeksWeeks 29 to 40. From 37 completed weeks the pregnancy is term, and anything up to 42 weeks is still within the normal range.

What changes in the last twelve weeks

Almost nothing new is built in the third trimester. What happens instead is growth and maturation: the baby roughly triples in weight, the lungs finish developing the machinery to breathe air, the brain grows faster than at any other point, and fat is laid down under the skin. That fat is why a baby born at 40 weeks looks so different from one born at 30.

For you, this is the stretch where pregnancy becomes physically demanding again. Sleep gets harder, breathing gets shallower as the uterus presses upward, and everything takes longer. Appointments become more frequent, usually fortnightly to 36 weeks and then weekly, because the things worth catching late in pregnancy develop quickly.

The growth curve through the last trimesterThe median goes from just over 1 kg at 28 weeks to about 3.6 kg at 40. The band widens sharply, which is why a healthy term baby can weigh anywhere from under 2.8 kg to over 4.5 kg.

Week by week, weeks 29 to 40

Weeks 29 and 30 — brain and bone

Around 1.2 to 1.5 kg. The brain surface folds rapidly, adding the ridges that make room for more tissue. Bone marrow takes over red blood cell production. The baby can now regulate its own temperature to a limited degree.

You may notice: breathlessness climbing stairs, heartburn most evenings, and vivid dreams.

Weeks 31 and 32 — running out of room

Around 1.7 to 1.9 kg. Most of the major organ development is complete apart from the lungs. Movements change character: less somersaulting, more stretching, rolling and pushing, because space is short. A growth scan is often done somewhere between now and 36 weeks.

You may notice: Braxton Hicks tightenings becoming more obvious, and pressure under the ribs.

Weeks 33 and 34 — lungs and immunity

Around 2 to 2.3 kg. The lungs are nearly ready. Antibodies pass across the placenta in large amounts from now, which is the protection a newborn lives on for the first months and the reason vaccination in pregnancy works.

You may notice: difficulty finding a comfortable sleeping position, and swelling in the feet by evening.

Weeks 35 and 36 — position starts to matter

Around 2.4 to 2.8 kg. Most babies settle head down by now, and from 36 weeks the position is worth acting on if they have not. The Group B strep swab is usually taken between 35 and 37 weeks. This is the point to have the bag packed.

You may notice: the baby dropping lower into the pelvis, which eases breathing and worsens the need to pass urine.

Weeks 37 and 38 — term

Around 2.9 to 3.2 kg. From 37 completed weeks the pregnancy is term and the baby is considered ready. Vernix and lanugo are shedding. The gut is filling with meconium, the first stool.

You may notice: a burst of energy and an urge to clean things, which is real and well recognised even if nobody can explain it.

Weeks 39 and 40 — waiting

Around 3.3 to 3.6 kg. Nothing much is left to do except gain weight and wait. Only about one baby in twenty arrives on the estimated date. If you reach 41 weeks your doctor will discuss induction, weighing the rising risks of continuing against the risks of starting labour off.

You may notice: irregular tightenings, a show, and being asked whether the baby has arrived by everyone you have ever met.

Counting movements, properly

This is the single most useful thing you can do in the third trimester, and it is widely misunderstood. The old advice to count ten kicks in twelve hours has largely been abandoned because it sets a threshold so low that a baby in trouble often still meets it. What replaced it is simpler and better: learn your own baby pattern, and act on a change from it.

Babies do not move less towards the end. Running out of room changes the character of the movements, not the number.
Movements should follow a recognisable daily rhythm by around 28 weeks. Most women find theirs is strongest when they finally sit or lie down.
If you think movements have reduced, lie on your left side and focus for two hours. Fewer than ten distinct movements in that time warrants a call.
Do not eat something sugary or drink cold water to make the baby move and then feel reassured. That advice delays presentation and has no evidence behind it.
Never wait until morning, and never feel you are wasting anyone time. Reduced movement is one of the few genuine warning signs in late pregnancy and every maternity unit expects these calls.

Reduced movements: call, do not wait A change in your baby usual pattern of movement is a reason to be assessed the same day, every time it happens, including if it happens repeatedly. Coming in and being told everything is fine is the expected outcome and the entire point.

How the baby is lying

The three positions you will hear discussedAround 96 in 100 babies are head down by 37 weeks. Before 36 weeks position means very little, because babies turn on their own constantly.

If the baby is still breech at 36 weeks, your doctor may offer an external cephalic version, a procedure in which the baby is turned by hand from outside the abdomen. It works in roughly half of attempts, is done where a theatre is available in case it is needed, and is not suitable for everyone. The alternative is a planned caesarean. Neither is a failure, and the choice depends on your circumstances rather than on a rule.

True labour or false labour

Almost everyone gets this wrong at least once, and being sent home in early labour is routine rather than embarrassing. The distinction below is the practical one.

	Braxton Hicks, or false labour	True labour
Timing	Irregular, no pattern that holds	Regular, and the gaps get shorter
Intensity	Stays the same or fades	Builds steadily and does not fade
Effect of moving	Often eases with rest, a warm bath or a change of position	Carries on whatever you do
Where you feel it	Mostly at the front of the abdomen	Usually starts in the lower back and wraps around to the front
Length	Varies, often under 30 seconds	Around 30 to 70 seconds and lengthening
Other signs	Usually nothing else	May come with a show, waters breaking, or loose stools

Signs labour is starting

A show: the mucus plug coming away, sometimes streaked with blood. Labour can still be days off.
Waters breaking, as a gush or a slow trickle. Note the time and the colour and call. Clear or straw is expected; green, brown or heavily bloodstained is not and needs immediate attention.
Contractions that become regular, longer and stronger over an hour or two.
Persistent low back ache that comes in waves rather than staying constant.
Loose stools, which is the body clearing the way and a genuinely common early sign.

What to pack, and when

Have the bag ready by 36 weeks. Around one baby in ten arrives before 37 weeks, and packing in a hurry while contracting is nobody idea of a good time. Keep the documents in the same bag, because those are the part people forget.

For you	For the baby	Documents and practicalities
Two or three loose nightdresses that open at the front for feeding	Six to eight cotton bodysuits and sleepsuits	All antenatal records and scan reports
Underwear you do not mind ruining, and maternity pads	Mittens, socks, caps and a soft blanket	ID, insurance papers and any pre-authorisation
A dressing gown, slippers and a shawl	Newborn nappies and cotton wool	Blood group card and a list of medicines you take
Toiletries, lip balm, hair ties and a towel	Two soft towels	Phone charger with a long cable, and cash
Nursing bras and breast pads	A going-home outfit	A written note of who to call and in what order
Snacks and water for whoever is with you	Car seat, fitted in advance if you have one	Numbers for your doctor and the hospital, saved and printed

Appointments and tests in the third trimester

Visits become fortnightly from 28 weeks and weekly from 36. Blood pressure, urine, fundal height and the fetal heart are checked every time.
A growth scan, usually between 32 and 36 weeks, estimating weight and checking fluid volume, placental position and blood flow in the cord.
A Group B streptococcus swab between 35 and 37 weeks. Carrying it is common and harmless to you; it matters only because antibiotics during labour protect the baby.
Repeat haemoglobin, because anaemia commonly worsens in the third trimester as blood volume peaks.
A non-stress test if there is any concern about movements, growth or your blood pressure, which records the fetal heart against movement for about twenty minutes.
Tetanus and other vaccinations as advised, which pass antibodies across to the baby.

Our pregnancy tests guide goes through each of these in detail, including what the numbers on a growth scan report actually mean.

Warning signs in the third trimester

Any of these, call the same day Reduced or changed fetal movements. Vaginal bleeding of any amount. A gush or trickle of fluid, particularly if it is green, brown or bloodstained. Severe or persistent headache, flashing lights or blurred vision. Pain under the ribs on the right side. Sudden swelling of the face or hands. Regular contractions before 37 weeks. Fever above 38 degrees. Severe constant abdominal pain, as distinct from contractions that come and go. Vomiting with abdominal pain.

Pre-eclampsia is the reason your blood pressure and urine are checked at every single visit. It often produces no symptoms until it is advanced, which is why the checks matter more than how you feel. If you have a headache that painkillers do not touch, or visual disturbance, treat it as urgent rather than waiting for the next appointment.

Thinking about the birth

It is worth having the conversation about how you would like the birth to go, while also holding it loosely. Birth plans are useful because they surface your preferences and make you ask questions in advance. They become a problem only when they are treated as a contract, because labour does not read them.

Who you want with you, and what you want them to do.
Pain relief: what you would like to try first, and what you would rather avoid unless it becomes necessary.
Positions and movement during labour, and whether you want to be free to move.
What you would want if a caesarean became necessary, because deciding this calmly in advance is far better than deciding it at speed.
Skin-to-skin contact and the first feed, which is worth stating because it is easy to lose in a busy room.
Anything cultural or religious that matters to you, said in advance rather than on the day.

Two things worth doing before 36 weeks Do the hospital route at the time of day you would actually travel, so nobody is discovering the traffic during contractions. And have one honest conversation with whoever is coming with you about what you want them to do if things move quickly, because that is the moment people freeze.

Fetal weight figures are from the WHO Fetal Growth Charts (Kiserud et al., PLOS Medicine 2017, CC BY 4.0). Everything here is general information for a low-risk pregnancy and does not replace the plan your own doctor has made with you.

Tools and guides for the last stretch

Due Date Calculator

How far along you are today, the milestones left, and the realistic range around your date.

Baby Growth Chart Calculator

For after the birth: weight, length and head circumference against the WHO standards.

Symptom Checker

Not sure whether something needs a call today? Tick what you have and see how urgent it is.

Second Trimester Guide

Weeks 13 to 28, if you want to go back over the anomaly scan or the glucose test.

Pregnancy Warning Signs

Sorted by urgency: what means go now, what means call today, and what can wait for your next visit.

Getting close?

From 36 weeks visits become weekly and the details start to matter: position, growth, blood pressure and your plan for the day itself. If you are approaching term, book in and let us go through it properly rather than in a rush.

Third trimester questions we hear most

Do babies really move less towards the end?

No, and this is the most dangerous myth in late pregnancy. Space runs out, so the character of the movements changes from somersaults to stretches, rolls and pushes. The number should not fall. A genuine reduction from your baby usual pattern is a reason to be assessed the same day, every time, however often it happens.

My baby is breech at 34 weeks. What happens now?

Very likely nothing yet. Plenty of babies turn between 34 and 37 weeks on their own. From 36 weeks, if the baby is still breech, your doctor may offer an external cephalic version, which is turning the baby by hand from outside. It succeeds in roughly half of attempts and is done where theatre facilities are available. If it is not suitable or does not work, a planned caesarean is the usual route.

How will I know it is real labour?

Real contractions become regular, the gaps get shorter, each one lasts longer, they intensify, and they carry on whatever you do. Braxton Hicks are irregular, stay the same or fade, ease with rest or a change of position, and are felt mostly at the front. If you are unsure, call. Being sent home in early labour happens constantly and no one minds.

My waters broke but I have no contractions. What do I do?

Call now rather than waiting. Note the time it happened and the colour of the fluid, because both change what happens next. Clear or straw coloured is expected. Green, brown or heavily bloodstained is not and needs immediate attention. Do not use tampons and avoid baths, because once the membranes are open the risk of infection rises with time.

Is it safe to go past my due date?

Anything from 37 to 42 completed weeks is term, and only about one baby in twenty arrives on the estimated date itself. Beyond 41 weeks the risks of continuing gradually rise, which is why induction is usually discussed around then. It is a conversation about weighing two sets of risk, not a rule, and monitoring usually becomes more frequent while you wait.

When should the hospital bag be ready?

By 36 weeks. Around one baby in ten arrives before 37 weeks, and the documents are what get forgotten in a rush. Keep the antenatal records, ID, insurance papers and blood group card in the same bag as the clothes, and do the hospital route once at the time of day you would actually be travelling.

Can I still exercise and have sex in the third trimester?

In an uncomplicated pregnancy, generally yes to both, with comfort as the practical limit. Walking and prenatal yoga remain useful right to the end. Sex is safe unless you have placenta praevia, unexplained bleeding, a history of preterm labour, or your waters have broken. If your doctor has told you otherwise for a specific reason, that overrides this.