24 weeks pregnant: baby is the size of an ear of corn

Your baby this week

Your baby's skin is red and wrinkled, since fat has not yet filled it out. Fingerprints and footprints are forming, and the lungs continue to develop. The startle reflex is working, and your baby may jump at a loud sound. The inner ear controls balance, so your baby knows which way is up.

The brain is growing quickly, and your baby has regular sleep and wake cycles. The taste buds are working, and the face looks like a newborn's, with lips, eyelids and eyebrows.

How it happens. Your baby swallows and breathes amniotic fluid, and this helps the lungs and digestive system to grow. If your baby hiccups, you may feel a light rhythmic twitch in your belly.

Your body this week

Your uterus is about 2 to 3 cm above your belly button, and it is growing about 1 cm a week. Your baby is moving a lot, and you can feel kicks that are firm and sometimes visible.

Your body is preparing for the coming months. You may feel your centre of balance shift, and your back and pelvis may ache more. You may also notice your waist, hips and breasts are much larger.

What does viability mean?

Viability means that a baby has a chance of surviving outside the womb with medical support. It is often set at about 24 weeks, but it is not a switch. Survival and health outcomes improve gradually week by week. Some babies born at 22 or 23 weeks survive in specialist centres, and some babies born later have serious health problems.

What affects a baby's chances:

• Gestational age. Every extra week in the womb improves outcomes.
• Birth weight and sex. Larger babies and girls tend to do better.
• Steroid treatment before birth. This helps mature the lungs.
• Care at birth. Being born in a hospital with a neonatal intensive care unit (NICU) matters.
• Whether it is a single or multiple pregnancy.

National guidance and hospital policies differ on how they approach extremely early births, so ask your provider how your hospital handles them. It is a hard subject, and you do not have to think about it all at once.

Signs of preterm labour

Preterm labour is labour that starts before 37 weeks. Call your provider or maternity unit straight away, or go to hospital, if you notice:

• Regular tightening of the belly that comes at intervals, and is not easing with rest, water and a change of position.
• Period-like cramps in the lower belly, which may come and go or be constant.
• A dull backache that is new, or comes in waves.
• Pelvic pressure, as if the baby is pushing down.
• A change in discharge. More watery, mucus-like or bloody discharge than usual.
• A gush or trickle of fluid from the vagina, which could be your waters breaking.

You do not need to be sure. Providers would rather check and find nothing than have you wait. If you are unsure whether the fluid is urine or waters, wear a pad and tell your provider what you see.

What happens if labour starts early

The team will assess you, check your baby's heartbeat, and may examine your cervix and take swabs. Depending on your situation, treatment may include:

• Corticosteroid injections. Given in the window when early birth is likely, roughly from about 24 to 34 weeks, they help mature your baby's lungs.
• Magnesium sulfate. Given before about 32 weeks, it can protect the baby's brain.
• Antibiotics. These may be given if your waters have broken or if you carry bacteria that could infect your baby.
• Medicines that slow contractions. They may delay birth for a short time so that other treatments can work.
• Transfer. If your hospital does not have a neonatal unit, you may be moved to one that does, ideally before the birth.

Who is at higher risk?

Anyone can go into preterm labour, and often there is no clear cause. Some things raise the risk, including a previous preterm birth, a short cervix, twins or more, some infections, smoking, and some medical conditions. If you are at higher risk, ask your provider about monitoring and prevention options, such as cervical length scans.