What to Expect in Your Third Trimester, A Complete Guide
Weeks 28 to 40+ covered in full, for expectant parents in Bexley, Erith, Dartford and surrounding areas
You've made it to the third trimester. The final stretch. Weeks 28 to 40 and sometimes a little beyond, are the weeks when everything becomes very real. Your bump is impossible to ignore, your baby is running out of room, and the birth you've been preparing for is now weeks, not months, away.
The third trimester brings its own set of physical challenges, emotional shifts, and practical milestones. It's also one of the most important times to be well-informed, because understanding what's normal, what to watch out for, and how to prepare makes an enormous difference to how you experience the final weeks of your pregnancy.
This guide covers everything you need to know, week by week and symptom by symptom.
What Is the Third Trimester?
The third trimester runs from week 28 of pregnancy until birth, typically around week 40, though anywhere between 37 and 42 weeks is considered within the normal range. Babies born before 37 weeks are considered premature; those born after 42 weeks are considered post-term.
Most first-time parents go into labour somewhere around their due date, give or take. Around half of babies arrive within five days of the estimated due date. The vast majority arrive within two weeks either side.
Your Baby's Development Week by Week
Weeks 28–32, Building Strength
By week 28, your baby weighs around 1kg and measures about 38cm from head to toe. Their brain is developing rapidly, forming the folds and grooves that will eventually give it its characteristic wrinkled appearance. The lungs are maturing, at this stage a baby born prematurely would need significant medical support to breathe, but the survival rate is good with specialist neonatal care.
Your baby's eyes are now open and beginning to distinguish between light and dark. They can hear your voice, your heartbeat, and sounds from the outside world, which is why familiar voices are so soothing to newborns from birth.
By week 32, your baby is around 1.8kg and their skin, which has been covered in a white waxy coating called vernix, is becoming less wrinkled as they lay down more fat. This fat will be crucial for regulating their temperature after birth.
Weeks 33–36, Growing Fast
These weeks are a period of rapid weight gain. Your baby is putting on around 200 grams a week, and by week 36 they'll weigh approximately 2.6kg. The lungs are now much more mature, a baby born at 34–36 weeks has a very high chance of doing well, though they may still need some support with feeding and temperature regulation.
By week 36, most babies have settled into a head-down position in preparation for birth. If your baby is not yet head-down at this point, your midwife will discuss this with you and may refer you for further assessment. Around 3–4% of babies remain in a breech position (bottom or feet first) at term.
The vernix coating is thickening, and your baby's fingernails have grown to the tips of their fingers, you may find your newborn arrives ready for their first nail trim.
Weeks 37–40+, Full Term
From 37 weeks, your baby is considered full term. By week 40 the average baby weighs just over 3kg and measures around 50cm. They are perfectly formed and ready for the world, though they'll continue to develop rapidly in the weeks and months after birth.
In these final weeks your baby's head may engage, drop down into the pelvis in preparation for birth. For first-time parents this often happens in the last few weeks of pregnancy. For women who have given birth before, engagement may not happen until labour begins.
You may notice your baby's movements changing in character as they have less room to move, but they should never stop moving altogether. The pattern may shift but the frequency and strength of movement should remain consistent. If you notice a reduction in movement at any stage of the third trimester, contact your maternity unit or midwife immediately, do not wait until your next appointment.
Third Trimester Symptoms, What's Normal, What to Watch For
Symptoms That Are Normal (But Uncomfortable)
Backache. As your bump grows and your posture adjusts, lower back pain is extremely common. Your centre of gravity shifts forward, the hormone relaxin softens your ligaments, and the weight of the baby puts increasing pressure on the lumbar spine and pelvis. Gentle exercise, warm baths, pregnancy pillows, and osteopathic treatment can all help significantly.
Pelvic girdle pain (PGP). Pain in the pelvis, hips, and groin, sometimes extending to the inner thighs, affects a significant proportion of pregnant women in the third trimester. It can make walking, climbing stairs, and turning over in bed genuinely difficult. PGP is not something you have to simply endure, osteopathic treatment, physiotherapy, and pelvic support belts can all provide meaningful relief. See our dedicated blog on PGP for full information, and contact Bexley Osteopathic Clinic for specialist pregnancy care in the Bexley area.
Braxton Hicks contractions. These irregular, practice contractions can begin earlier in pregnancy but often become more noticeable in the third trimester. They are usually painless or mildly uncomfortable, a tightening sensation across the abdomen that comes and goes without a regular pattern. Unlike true labour contractions, Braxton Hicks do not increase in frequency, length, or intensity over time. They are completely normal.
Heartburn and indigestion. As the uterus expands it pushes the stomach upward, causing the contents to reflux into the oesophagus. The burning sensation in the chest and throat is extremely common in the third trimester. Eating smaller, more frequent meals, avoiding lying down immediately after eating, and propping yourself up with pillows at night all help. Gaviscon and certain antacids are considered safe in pregnancy, check with your midwife or pharmacist.
Swollen ankles and feet. Fluid retention is common in pregnancy, particularly in the legs and feet, and tends to worsen in the third trimester, especially in warm weather or after a period of standing. Elevating your feet when resting, staying well hydrated, and avoiding standing for long periods all help. Gentle pregnancy massage can also support lymphatic drainage and reduce swelling.
However, if swelling comes on suddenly, is severe, or is accompanied by a headache, visual disturbances, or pain below the ribs, contact your midwife or maternity unit immediately, as this can be a sign of pre-eclampsia (see below).
Shortness of breath. As your uterus rises it pushes against your diaphragm, leaving less room for your lungs to fully expand. Feeling a little breathless on exertion is normal. You may find that breathing becomes slightly easier in the last few weeks as your baby's head engages and drops lower in the pelvis.
Frequent urination. The growing uterus puts increasing pressure on the bladder, which means many women find themselves needing to wee far more frequently in the third trimester, including multiple times overnight. This is normal. A small amount of leakage when sneezing, coughing, or laughing is also very common, pelvic floor exercises can help, and if symptoms persist after birth a pelvic floor physiotherapist or Mummy MOT® assessment can support recovery.
Difficulty sleeping. Finding a comfortable position becomes increasingly challenging as your bump grows. A pregnancy pillow (particularly a full-length body pillow or a wedge) can make a significant difference. Sleeping on your side is recommended and specifically your left side is often recommended as it optimises blood flow to the placenta. However, if you wake up on your back, don't panic, simply turn back onto your side. The risks are associated with spending extended periods on your back, not with briefly rolling onto it in your sleep.
Tiredness. The first trimester exhaustion, which may have lifted in the second trimester, often returns in the third. You're carrying significantly more weight, sleeping less comfortably, and your body is working hard to prepare for birth. Rest as much as you can and accept help when it's offered.
Nesting instinct. A sudden surge of energy and an overwhelming urge to clean, organise, and prepare the home is completely normal in late pregnancy. Lean into it, but don't exhaust yourself. The nesting instinct is real and it serves a purpose.
Varicose veins and haemorrhoids. Increased blood volume and pressure on the veins from the growing uterus can cause varicose veins in the legs and haemorrhoids (varicose veins in the rectum). Both are uncomfortable but manageable. Support tights, staying active, and avoiding straining on the toilet (staying well hydrated and eating plenty of fibre helps) all reduce symptoms.
Stretch marks. As the skin stretches to accommodate your growing bump, stretch marks may develop on the abdomen, breasts, hips, and thighs. They are extremely common and there is no product proven to prevent them, though keeping the skin well moisturised can help with any associated itching.
Warning Signs, Contact Your Maternity Team Immediately
These symptoms require prompt medical attention and should never be waited out:
Reduced or absent fetal movement. If you notice your baby moving less than usual, or if movement stops, call your maternity unit straight away. Do not wait until the next day. Do not use a home doppler to check for a heartbeat, and this this can give false reassurance. Call your midwife or maternity unit.
Signs of pre-eclampsia. Pre-eclampsia is a serious pregnancy condition involving high blood pressure and organ involvement. Warning signs include severe headache that won't go away, vision changes (blurring, flashing lights, spots), severe swelling of the face, hands, and feet that comes on suddenly, pain below the ribs on the right side, and feeling generally unwell. Pre-eclampsia requires urgent medical assessment.
Vaginal bleeding. Any significant vaginal bleeding in the third trimester should be assessed urgently. Light spotting after intercourse or an internal examination can be normal, but fresh red bleeding should always be checked.
Regular painful contractions before 37 weeks. If you experience regular contractions, particularly if they are becoming stronger and more frequent, before 37 weeks of pregnancy, contact your maternity unit, as this may indicate preterm labour.
Severe abdominal pain. Constant, severe pain that doesn't ease is different from normal pregnancy discomfort and warrants urgent assessment.
Sudden severe swelling on one side of the body. While bilateral ankle swelling is common in pregnancy, swelling that is severe and one-sided, particularly in the calf, can indicate a deep vein thrombosis (DVT) and should be assessed promptly.
Your Third Trimester Appointments
Midwife Appointments
In the third trimester, your midwife appointments become more frequent. For a straightforward first pregnancy, you can expect appointments at weeks 28, 31, 34, 36, 38, 40, and 41 if you go past your due date.
At each appointment your midwife will check your blood pressure, test your urine, measure your bump (fundal height), and listen to your baby's heartbeat. From around 36 weeks they'll also check your baby's position.
If your pregnancy has any complications or risk factors, you may have additional appointments or be under the care of a consultant obstetrician as well as your midwife.
The 28-Week Blood Tests
At your 28-week appointment, you'll be offered blood tests to check your blood count and screen for gestational diabetes (if not already done), as well as a repeat check for anaemia. If you are rhesus negative, you'll be offered anti-D injections at 28 and 34 weeks to protect a future pregnancy.
Growth Scans
If there are any concerns about your baby's growth, either too large or too small for dates, you may be referred for additional growth scans in the third trimester. These measure your baby's estimated weight, head circumference, abdominal circumference, and assess blood flow through the placenta and umbilical cord using Doppler. A referral for a growth scan is not automatically a cause for alarm, it's a monitoring tool.
Preparing Your Body in the Third Trimester
Staying Active
Gentle exercise throughout the third trimester is beneficial for both you and your baby, as it helps maintain fitness and muscle tone, reduces back pain, supports mood, and may help with labour. Walking, swimming, pregnancy yoga, and aquanatal classes are all excellent options.
Listen to your body. What you can comfortably do will change as your bump grows, and that's completely normal. Avoid contact sports, exercises with a risk of falling, and anything that involves lying flat on your back from the second trimester onwards.
Pelvic Floor Exercises
Your pelvic floor, and the hammock of muscles supporting your bladder, uterus, and bowel, is under significant strain throughout pregnancy. Regular pelvic floor exercises (Kegel exercises) throughout the third trimester help maintain strength and support recovery after birth.
To find your pelvic floor muscles: imagine you're trying to stop yourself from passing urine. The muscles you squeeze are your pelvic floor. Squeeze and hold for up to ten seconds, then release fully. Aim for ten repetitions, three times a day.
Sleep Positions
From around 28 weeks, sleeping on your side is recommended. Research has shown that going to sleep on your back in the third trimester is associated with a small increased risk of stillbirth, thought to be related to compression of the large blood vessels that run along the back of the abdomen. Sleeping on your side, either side is fine, avoids this.
A pregnancy pillow or a pillow tucked between your knees and under your bump can make side-sleeping significantly more comfortable.
Perineal Massage
From around 34–36 weeks, daily perineal massage, gentle massage of the skin between the vagina and anus, can help prepare the perineum for stretching during birth and reduce the risk of tearing. Your midwife can show you how to do this, and there is good evidence that it makes a difference, particularly for first-time parents.
Your Third Trimester Checklist
Use this as a guide to what to have in place before your baby arrives:
By 32 weeks:
Book your antenatal course if you haven't already, courses fill up quickly and most recommend completing them by 36 weeks
Research your birth place options, hospital labour ward, midwife-led unit, or home birth
Start thinking about your birth preferences
By 34–36 weeks:
Pack your hospital bag, don't leave this to the last minute
Install your car seat and have it checked
Wash baby clothes and have the essentials ready
Start your birth plan and discuss it with your birth partner
Confirm your maternity leave start date with your employer
Make sure your partner has notified their employer of their intention to take paternity leave
By 36–37 weeks:
Complete your antenatal course
Have a conversation with your midwife about your birth preferences
Make sure your birth partner knows the route to the hospital and where to park
Know the signs of labour and when to call your maternity unit
Have the maternity unit number saved in your phone
Ongoing throughout:
Attend all midwife and consultant appointments
Monitor your baby's movements and contact your maternity unit immediately if concerned
Rest when you can
Accept help
Your Hospital Bag, What to Pack
For labour:
Your birth plan and maternity notes
Snacks and drinks (for you and your birth partner)
TENS machine/birthing comb if you plan to use one
Comfortable, loose clothing
Pillow from home if you'd like one
Phone charger and portable battery
Headphones and a playlist if music helps you relax
Lip balm, gas and air can dry your lips
For after the birth:
Comfortable, loose clothing for the postnatal ward (button-front tops if breastfeeding)
Nightwear, dark colours are practical
Maternity pads (you'll need more than you think, pack at least two packs)
Comfortable, supportive nursing bras or crop tops
Toiletries
Going-home outfit for you
For your baby:
Vest and sleepsuit (pack two or three sizes, you won't know how big they'll be)
Hat and scratch mitts
A blanket or muslin
Car seat, installed and ready in the car before your due date
Signs of Labour, When to Go to Hospital
Knowing the difference between early labour, established labour, and the signs that it's time to call your midwife or head to hospital is one of the most important things to understand before your due date.
Signs that labour may be beginning:
A show, a blood-tinged mucus plug that has sealed the cervix during pregnancy. This can happen days before labour starts or at the very beginning.
Backache, a persistent low backache that is different from your usual pregnancy aches
Mild, irregular cramps or tightenings
Your waters breaking, a gush or a slow trickle of clear or pale yellow fluid. If your waters break, call your maternity unit straight away.
When to call your maternity unit:
Your waters break
You are having regular contractions, typically when they are coming every five minutes, lasting at least a minute, and have been doing so for at least an hour (the 5-1-1 rule)
You have any bleeding
You have any concerns about your baby's movements
You feel unwell or have any of the warning signs listed earlier in this guide
In a first pregnancy, labour typically takes longer and you're encouraged to stay at home in early labour where possible, keeping mobile, using a TENS machine, having a warm bath, and resting. Your midwife or maternity unit can advise you over the phone on when to come in.
Your Emotional Wellbeing in the Third Trimester
Anxiety About Birth
It is entirely normal to feel anxious about labour as your due date approaches, particularly if it's your first baby and you don't know what to expect. The antidote to birth anxiety is almost always information and preparation. Understanding what labour involves, knowing your options, and having practised coping strategies all significantly reduce fear.
If your anxiety feels overwhelming, persistent, or is affecting your daily life, please speak to your midwife. Antenatal anxiety is common and there is support available, you don't have to manage it alone.
The Mental Shift of the Final Weeks
The third trimester often brings a significant psychological shift. Priorities change. The world outside can start to feel less important. Many people find themselves becoming quieter, more internal, more focused. This is normal and healthy, it's preparation.
Give yourself permission to slow down. The outside world will still be there after the birth. These weeks are for you and your baby.
Your Relationship
The arrival of a baby changes every relationship. The third trimester is a good time to talk openly with your partner about practical arrangements, expectations for the early weeks, how you'll support each other, and how you're both feeling. Attending an antenatal course together gives you a shared language and a shared foundation of knowledge, which makes a real difference when you're navigating the early days of parenthood together.
Getting Support Locally
Osteopathic and Physical Support
If you're experiencing back pain, pelvic girdle pain, or any musculoskeletal discomfort in the third trimester, don't wait it out. Seeking treatment early generally leads to better outcomes.
We recommend Bexley Osteopathic Clinic at 16A Bexley High Street, DA5 1AD, a specialist clinic with nearly four decades of experience in pregnancy care, offering osteopathic treatment, pregnancy massage, acupuncture, and postnatal services including the Mummy MOT®.
Tel: 01322 529326 | Monday–Friday 8:45am–7:00pm | Saturday 9:00am–2:00pm
Private Pregnancy Scans
If you'd like additional reassurance scanning in the third trimester, a wellbeing scan to check growth, position, or amniotic fluid, My Scan Hub at Bluewater Shopping Centre in Dartford offers consultant-led private pregnancy scans with same-day appointments, no referral needed, and results delivered securely online.
Tel: 0800 151 2227 | Guildhall Outer Car Park, Bluewater, Dartford, DA9 9ST
Antenatal Courses
If you haven't yet booked your antenatal course, now is the time. We recommend completing your course by 36 weeks, which means booking by around 30–32 weeks at the latest for most course formats.
View our upcoming course dates and book your place here.
From Little Village Antenatal
The third trimester is when everything we cover in our antenatal courses at Little Village Antenatal starts to feel very relevant, very quickly. Birth positions, pain relief, when to go to hospital, what to pack, how to write a birth plan, what happens if things don't go to plan, all of it becomes urgent and real in these final weeks.
Our courses are small, warm, and comprehensive. We're based in Erith and serve families across Bexley, Dartford, Sidcup, Belvedere, and the wider Southeast London and Kent area. Partners are fully included. Infant feeding, infant first aid, and the postnatal period are all covered.
We're FEDANT registered (National Register Entry Number: 13969).
View our upcoming course dates and book your place here.
You've grown a whole human being. Let us help you prepare for what comes next.
This blog is for informational purposes only and is not a substitute for advice from your midwife, GP, or obstetric team. If you have any concerns about your health or your baby's wellbeing during pregnancy, always contact your maternity unit or midwife promptly. In an emergency, call 999.