Pregnancy Week 24: Gestational Diabetes Screening and Your Baby at Six Months

8 min read

Quick answer: At 24 weeks your baby is around 30cm from crown to heel and about 600 grams, and is now considered viable with specialist medical care. The NHS offers a glucose tolerance test between 24 and 28 weeks to women with certain risk factors, such as a BMI over 30 or a previous baby weighing 4.5kg or more. Braxton Hicks tightenings are normal, but call your maternity unit immediately if they become regular or painful.

What parents need to know

You're at 24 weeks — six months pregnant! This is another meaningful milestone, and your baby is now considered viable (capable of survival with specialist medical care if born now, though of course the aim is to stay pregnant for many more weeks). This week, some women will be offered screening for gestational diabetes, a condition that affects a proportion of pregnant women and is important to detect and manage.

Baby's length	About 30cm from crown to heel
Baby's weight	Around 600 grams
Weekly weight gain	Roughly 200 grams a week from now
GTT timing	Usually offered between 24 and 28 weeks
Uterus position	Roughly at your belly button

How big is your baby at 24 weeks?

Your baby is now about the size of a sweetcorn cob — approximately 30cm from crown to heel and weighing around 600 grams. Every week from now they'll be gaining roughly 200 grams in weight as fat deposits develop.

What's happening with your baby?

Your baby's face is now almost fully formed and distinctly individual. Their skin, though still reddish and somewhat translucent, is becoming more opaque as fat accumulates. The lungs are continuing to develop surfactant, which will be critical for breathing after birth. Your baby's brain is growing rapidly and the cerebral cortex is beginning to develop folds and grooves — a process that will continue into early childhood.

Your baby is increasingly responsive to the outside world. They react to your voice, to music, and to sudden noises. They may also respond to light if your bump is illuminated. Their movements are well established and should be felt regularly throughout the day.

What is gestational diabetes?

Gestational diabetes is a type of diabetes that develops during pregnancy and usually resolves after birth. It occurs when the body cannot produce enough insulin to meet the increased demands of pregnancy, leading to raised blood sugar levels. It affects around 6% of pregnancies in the UK, according to Diabetes UK and NHS statistics.

Gestational diabetes can usually be managed successfully through diet, lifestyle changes, and sometimes medication, but it does require careful monitoring as it can increase the risk of your baby growing larger than average, premature birth, and other complications.

Who is offered gestational diabetes screening?

In England, the NHS offers a glucose tolerance test (GTT) to women with certain risk factors. These include being over 40, a BMI over 30, a family history of diabetes (first-degree relative), a previous baby weighing 4.5kg or more, a history of gestational diabetes in a previous pregnancy, having had a gastric bypass or other weight-loss surgery, or a South Asian, Black African, African Caribbean, or Middle Eastern family background. The GTT is usually offered between 24 and 28 weeks of pregnancy. If you're unsure whether you should be offered screening, ask your midwife.

The GTT involves not eating or drinking for 8 to 10 hours beforehand (you can usually drink water, but check with the hospital), having a blood test in the morning, drinking a glucose solution, waiting two hours, and then having another blood test. Results are usually available within a few days.

What's happening in your body?

At 24 weeks, your uterus reaches roughly to your belly button and is clearly visible. You may be experiencing increased Braxton Hicks contractions — painless, irregular tightenings of the uterus that are the womb's way of ‘practising’ for labour. These are entirely normal and are not a sign of labour. However, if they become regular or painful, or you have any bleeding or fluid leaking from your vagina, call your maternity unit immediately, as regular tightenings before 37 weeks can be a sign of premature labour. If the pain or bleeding is severe, call 999.

When to get help

Some symptoms in pregnancy can be a sign of something serious and need checking quickly. This is who to contact, and how soon.

Call 999 if:

you're bleeding from your vagina and the bleeding is heavy (soaking a period pad soon after putting it on), or you also have severe pain in your tummy, pain in your shoulder, or feel sick, faint, dizzy or lose consciousness
you think your baby is coming now and you have a strong urge to push (ask for an ambulance)
you have severe difficulty breathing (you're gasping, choking or not able to get words out) or your chest feels tight or heavy
you have pain and swelling in one leg and you also feel short of breath or have chest pain. A blood clot in the leg can travel to your lungs, which can be life-threatening
you have possible signs of sepsis, such as breathing very fast, being confused or having slurred speech, blue, pale or blotchy skin, a rash that does not fade when you press it, or a very high or very low temperature. Being pregnant makes sepsis more likely
you do not feel you can keep yourself safe (a mental health emergency is as serious as a physical one)

Always call 999 if you think it's a life-threatening emergency, no matter what stage of pregnancy you are.

Call your midwife or maternity unit now if:

your baby is moving less than usual, you cannot feel your baby moving anymore, or there is a change to your baby's usual pattern of movements
you have light bleeding or spotting, even if you have no pain or only mild tummy pain
you have stomach pain that is severe or does not go away after you've rested for 30 to 60 minutes, or stomach pain with regular cramping or tightenings, lower back pain, or pain when you pee
you're less than 37 weeks pregnant and you have a gush or trickle of fluid from your vagina (this could be your waters breaking), regular contractions or tightenings, period-type pains, or backache that's not usual for you
you have signs of pre-eclampsia: a severe headache that does not go away with simple painkillers, vision problems (such as blurred vision or seeing flashing lights), pain below the ribs, sudden swelling of the face, hands or feet, feeling very unwell, heartburn that does not go away with heartburn medicines, or being sick (vomiting)
your skin is very itchy (for example, it keeps you awake at night), the palms of your hands or soles of your feet are itchy, or the itching is worse at night. This can be a sign of a liver condition called intrahepatic cholestasis of pregnancy (ICP) that needs urgent treatment
your breathlessness comes on suddenly, you're out of breath when you're lying down, or you're breathless and also have chest pain or feel dizzy
you have pain or swelling in one leg, usually in the calf or thigh. This could be a blood clot (deep vein thrombosis, or DVT), which is more likely when you're pregnant
you have a high temperature (38C or above), or you feel hotter than usual or shivery. A high temperature can be a sign of an infection, so it's important to get it checked

Also call your maternity unit immediately if you have stomach pain and:

vaginal discharge that's unusual for you or fluid leaking from your vagina
your pee looks cloudy, pink, red or brown

If your baby's movements change, do not wait until the next day: call immediately, even if it's the middle of the night. Do not use a home doppler to check the heartbeat yourself. Even if you hear a heartbeat, this does not mean your baby is well.

If you cannot reach them, or you're not sure what to do, call NHS 111.

Speak to your midwife or GP if:

you have not felt your baby move by 24 weeks. Most people start to feel movements between 16 and 24 weeks. If this is your first baby, you might not feel them until after 20 weeks
you're worried about your mental health, or stress, anxiety or low mood are affecting your day-to-day life. If you need urgent help for your mental health, call 111 and select the mental health option, or ask for an urgent GP appointment

Your week 24 checklist

This week:

Discuss gestational diabetes screening with your midwife if you have risk factors.
Continue monitoring your baby's movements.
Continue pelvic floor exercises daily.
Stay well hydrated.
Consider booking antenatal classes if you haven't already.

Sources & further reading

General information, not individual medical advice. Speak to your GP, midwife or health visitor about your baby’s needs.