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Trimester 2 · Week 23 of 40

Week 23 of pregnancy: Half a Kilogram

Rapid weight gain begins for your baby. For you: the signs of preterm labour, and how to tell normal discharge from an infection.

Last updated 28 September 2026

What's happening this week?

Your baby is gaining weight quickly now and may be close to half a kilogram. The lungs are building airways and blood vessels, but they are still immature. This week is a good time to learn the signs of preterm labour, because recognising them early and getting to hospital quickly can make a real difference. It is also common to notice more vaginal discharge in mid-pregnancy. Most of it is normal, but some changes point to an infection that needs treating.

Baby's development

Your baby is entering a stretch of rapid weight gain that continues through the rest of pregnancy. The skin is still thin, red and wrinkled, because there is little fat underneath yet; as fat builds over the coming weeks, the skin will become smoother and less see-through. Your baby is also getting longer and stronger, and the weight gained in the weeks ahead is a big part of what helps babies cope after birth.

In the lungs, the canalicular stage continues: the smallest airways are branching and a network of tiny blood vessels is growing around them. This is groundwork for breathing, but the air sacs and surfactant are not ready. Scans around now may show rapid eye movements under the closed lids. These are a sign of a maturing nervous system, not dreaming, and organised sleep states come much later.

A baby born this early is still in the periviable window. Some survive with intensive care at specialist centres, but outcomes vary greatly. That is why doctors act quickly when there are signs of early labour, and why knowing those signs yourself is so useful this week.

Your baby's size

About the size of an ear of corn

28.9 cm

11.4 in · Length

501 g

Weight

Week 23

Gestational age

The 501 g figure is an average; weights of about 500–600 g are typical at 23 weeks, and a healthy baby can be well outside that. Length is now given head to heel, roughly 28–29 cm. Your own scan estimate may differ, and fruit sizes are only a rough picture.

Your body this week

Many people notice more vaginal discharge in pregnancy. A light, white or creamy discharge with no strong smell or itch is normal. Changes such as a strong or fishy smell, green or yellow colour, thick curd-like discharge with itching, soreness, or a watery leak are not normal and should be checked.

Urine infections are also worth knowing about. Burning, urgency or cloudy urine needs a same-day check; fever, back or loin pain or vomiting with these symptoms may mean a kidney infection and should be seen urgently.

Preterm labour means labour that starts before 37 weeks. It can begin with signs that are easy to dismiss: tightenings that come regularly, period-like cramps, a dull backache that comes and goes, pressure low in the pelvis, a mucus show or a trickle of fluid. Any of these before 37 weeks needs checking at hospital straight away.

Your bump is growing steadily, so back ache, heartburn and puffy ankles may continue. Your blood volume is still rising and will not reach its peak until about 32–34 weeks.

Symptoms you may notice

Every pregnancy is different - you may have some, all or none of these.

White discharge: More discharge is common. Wear cotton underwear and avoid douches and perfumed washes. Smelly, coloured, itchy or watery discharge needs a check.
Burning when passing urine: Could be a urine infection, which is more common in pregnancy. Contact your doctor the same day; do not wait for it to pass.
Back ache: Common as your posture changes. Backache that comes and goes in a rhythm, especially with tightenings, may be a sign of preterm labour.
Swollen ankles: Gradual evening swelling is usual. Sudden swelling of the face or hands needs a same-day check.
Pelvic pressure or cramps: A heavy, pushing feeling low down or period-like cramps can simply be the growing uterus, but before 37 weeks, especially if they come in waves or with tightenings, go to hospital to be checked.

Medical care and tests

Urine checks
Routine
Every antenatal visit
In India, urine is tested for protein and sugar at each visit. Tell your doctor about any urinary symptoms; a urine culture may be sent to look for infection, which is commonly done in private practice.
Assessment for threatened preterm labour
Only if needed
Any time before 37 weeks, if you have symptoms
If you go to hospital with signs of early labour, you will be examined and monitored. If birth seems likely, doctors may give corticosteroid injections to help your baby's lungs mature faster and arrange care where specialist neonatal support is available.
Anomaly rescan
Only if needed
UK latest around 23 weeks
Where earlier views were incomplete, a final repeat is sometimes done this week.
Td vaccine
Routine
Two doses four weeks apart, or one booster
Check your antenatal card to make sure your Td doses have been given as India's schedule advises.

The 24–28 week glucose test is coming up, and in India the second antenatal visit window closes at 26 weeks, so check which appointments you still need.

Nutrition this week

Hydration is this week's focus. Aim for more than 2 litres of fluid a day, and more in hot weather or if you are sweating.
Water, chaas, lassi with little sugar, jeera water, clear soups and dal all count. Limit sugary cold drinks and packaged juices.
Food safety still matters: drink boiled or filtered water, choose freshly cooked hot food, wash fruit and vegetables well and avoid pre-cut fruit from stalls.
Keep up iron and calcium foods, and take your tablets as prescribed; constipation from iron can be eased with fibre and fluids, such as fruit, vegetables, whole grains and isabgol if your doctor agrees.

Movement and exercise

Walking and gentle prenatal yoga remain good choices. Keep sessions moderate, stay cool and drink water before and after, especially in hot or humid weather.
If you feel regular tightenings, pelvic pressure or notice fluid during exercise, stop and contact your maternity unit rather than waiting to see if it passes.
Cat–cow and pelvic tilts on hands and knees ease back ache without needing to lie flat on your back.

Things to keep in mind

Know the route to your hospital and how you would get there at any hour, including which ambulance service works in your area.
Keep your antenatal card and reports in one folder you can grab quickly, so any hospital you reach can see your history.
Do not hold in urine for long periods, and wear breathable cotton underwear.
Do not use vaginal washes, douches or over-the-counter creams for discharge without advice; get the cause checked instead, because different infections need different treatment.

When to contact your doctor

Call your doctor or midwife the same day if you have

Discharge that smells, itches, is green or yellow, or looks different from usual.
Burning or stinging when passing urine, or needing to go urgently.
Any vaginal spotting or light bleeding.
A fever of 38°C or more.
Sudden swelling of the face, hands or feet, or a headache that will not go away.

Get emergency care now if you have

Regular tightenings or contractions, period-like cramps, pelvic pressure or backache that comes and goes.
Any leak of fluid from the vagina, whether a gush or a trickle.
Bleeding, or a mucus show, before 37 weeks.
Urinary symptoms with fever, loin pain and vomiting.
Severe headache with vision changes, or a fit.

In India, call 108 for an ambulance, 102 for free transport for pregnant women in many states, or 112 for any emergency - or go straight to your nearest hospital with a maternity unit.

If something feels wrong, trust that feeling and call - you never need to wait for your next appointment.

Questions to ask your doctor

Which signs of early labour should make me come straight in?
Is my discharge normal, or should it be tested?
Should my urine be sent for culture?
Am I at higher risk of preterm birth, and does anything need monitoring?

Week 23 checklist

Preterm labour signs saved on your phone
Maternity unit and ambulance numbers stored
Antenatal records in one folder
Td doses checked on your card
Water bottle with you every day

Frequently asked questions

What are the signs of preterm labour?

Before 37 weeks, watch for regular tightenings or contractions, period-like cramps, pressure in the pelvis, backache that comes and goes, a mucus show, bleeding, or fluid leaking from the vagina. Any of these needs assessment at hospital straight away. Do not wait to see if it settles, and do not worry about it being a false alarm.

How do I know if my discharge is an infection?

Normal pregnancy discharge is usually thin, white or creamy, with little smell. Signs of infection include a strong or fishy smell, green or yellow colour, thick white discharge with itching or soreness, or pain when passing urine. A watery leak can be amniotic fluid. Any of these should be checked; do not treat yourself with over-the-counter products.

What happens at hospital if I might be in preterm labour?

You will be examined, and your contractions and your baby's heartbeat monitored. If birth looks likely, doctors may give you corticosteroid injections, which help your baby's lungs mature faster, and may arrange care at a hospital with specialist neonatal support. Sometimes the signs settle and you can go home. Going in is never a waste of anyone's time.

This page is general information, not a diagnosis or a substitute for care from your own doctor or midwife. Pregnancies differ, and timings here are typical ranges rather than deadlines. Read our medical disclaimer and editorial policy.