Mother and Baby

Your second trimester: What to expect!

Section: Pregnancy
second trimester

Your second trimester is an incredibly important time in your baby’s development. You might be able to find out your baby’s sex at your scan – which is normally at 20 weeks of pregnancy – if you want to find out, that is. Here's what else you've got to look forward to week by week. 

When does the second trimester start?

Your second trimester of pregnancy is the three months in the middle of your pregnancy, it starts on week 13 and ends after week 27.


Baby's growth in the second trimester:

By the end of this trimester, your baby will grow hair and become able to swallow and hear things around her. She will even have tiny fingernails and fingerprints.

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Week 13: Your baby's vocal chords begin to develop 

During week 13, your little one will start developing bones in her arms and legs and her intestines, which up until now have been growing inside the umbilical cord, will move to their permanent address in your baby’s abdomen.
Your baby's vocal chords begin to develop and your baby is beginning to make urine and release it into the amniotic sac, making amniotic fluid. 
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Week 14: Baby's skin is covered in a downy 'fur coat' 

Your baby’s skin is now covered in hair that keeps them warm until they build more fat in the third trimester. Eyelids, eyebrows, eyelashes, nails, and hair are formed. Your baby will start to use her facial muscles to smile and grimace and will have fully developed genitals. 

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Week 15: Eyes will start to become sensitive to light

By 15 weeks, they will have ears on either side of their head and their eyes are moving from the side of her head to the front of her face. The eyes will start to become sensitive to light, even though they remain closed, they can now register bright light. Your baby's scalp hair pattern also is forming.
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Week 16: Your baby can suck their thumb 

Your baby can suck their thumb, yawn, stretch, and make faces, though they don't really have much control over this. At the moment, they've not got any baby fat yet and their skin is still translucent. 
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Week 17: Baby's heartbeat begins to regulate 

Baby's heart is now regulated by the brain, which means it’s not beating so randomly any more, but will still be beating about twice as fast as yours. Your little one will also get fingerprints during this week! 
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Week 18: Baby’s hearing is now getting more acute

 Your baby’s hearing is now getting more acute, which means now is a good time to start talking and signing to your growing bump! 
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Week 19: Fat is beginning to develop on your baby's body 

This week, fat is starting to develop on your baby’s body, although she’ll still look pretty skinny.
She’ll also be covered in a waxy substance, medically referred to as vernix caseosa. This is greasy and white and made up of hair, oil and dead skin cells. It might not sound too appealing, but it does an important job protecting your baby’s soft and sensitive skin from the amniotic fluid she’s living in. 

For girls, the uterus and vaginal canal are forming.
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Week 20: Your baby is regularly sleeping and waking

If you’re carrying a little girl, she’ll already have seven million primitive eggs in her ovaries, this will be down to two million when she’s born. If you’re carrying a boy, his testicles will start moving from his abdomen this week. You baby is regularly sleeping and waking and can be awakened by loud noises/your movements. 
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Week 21: Baby begins to kick 

Baby's arms and legs will now be in proportion, the neutrons between the brain and muscles are connected, and the cartilage in your baby’s body will be turning to bone, all of which gives your baby more control over the movement of her limbs - meaning you're much more likely to feel your baby kick. 
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Week 22: Baby's hair becomes visible

Your baby is starting to look more like a newborn than ever, with distinct lips, eyelids and eyebrows, and even tiny tooth buds. Their hair is becoming visible and thier eyebrows have developed. 
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Week 23: ​Your baby might begin hiccupping

Your baby might begin hiccupping, causing jerking movements. Her lung’s blood vessels are developing to prepare for breathing in the outside world, and she’s also becoming acclimatised to familiar noises, such as the roar of cars outside or the sound of your dog barking. 
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Week 24: Your baby will begin to practise breathing

  Your baby’s lungs are maturing every day and are beginning to produce a substance called surfactant, which helps to keep tiny air sacs in the lungs called alveoli open. She’ll even start practising breathing in the womb, moving her chest up and down and exhaling amniotic fluid. Your baby's skin is wrinkled, translucent and pink to red because of visible blood in the capillaries.
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Week 25: Your baby’s hands will develop creases in the palms 

Your baby’s hands will develop creases in the palms this week (cute!), and soon sweat glands will form in her skin. Your baby is spending most of their sleep time in REM sleep and can recognise the sound of your voice. 
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Week 26: ​Your baby’s heart rate will have slowed down considerably

Your baby’s heart rate will have slowed down considerably by this week too, from 180 beats per minute to 140 to 150 beats per minute. 
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Week 27: Your baby's brain is really active

Your baby’s brain is really active these days, as more brain tissue is developing. She’s an active foetus, sleeping and waking up regularly, opening and closing their eyes and sucking their fingers too. She’s about the size of a head of broccoli! 

Choices and decisions during your second trimester

It’s time for a few important decisions. Do you want to know your baby’s sex or would you prefer to keep it a surprise? Who do you want as your birth partner? Where would you like to give birth? Don’t rush, and give it all a lot of thought.

Antenatal appointments

Remember to keep up with your antenatal appointments this trimester - you will have a few. At week 16, you’ll be told about the anomaly scan, which you’ll be offered at 18-20 weeks. The anomaly scan checks the physical development of your baby.


If you work, you must tell your employer about your pregnancy at least 15 weeks before the beginning of the week your baby is due. You will need a MAT B1 form – find out more here.

Even though it may seem ages before the baby will arrive, start looking for good childcare if you are planning to go back to work. 

Go shopping

Do some maternity clothes shopping. Maternity clothes can be stylish as well as practical – check out our Maternity Fashion section to see for yourself. Stay active – check out our section on exercise during pregnancy for top tips and advice, including the best pregnancy fitness DVDs. Oh and don't forget to think about investing in a pelvic floor trainer.

Bond with your bump.

This is an amazing time when you start feeling the life inside you moving and reacting to your voice. Make the most of it and encourage your partner to do the same.

Your body changes

Hopefully, during your second trimester, your morning sickness has stopped. Your growing bump will start putting some extra pressure on your back and you are going to feel it. To soothe any aches, try sleeping on your side. Many pregnant women find they get stretch marks. Don't worry, these are completely normal. 

You might experience bleeding gums, so make an appointment with your dentist. You may also start seeing varicose veins – that is because of the extra blood flowing in your system. This can be helped by having a more active lifestyle and regularly lifting your legs above your heart level. The now-familiar heartburn and constipation are likely to remain, however, they can be helped by physical activity too.

The second half of your pregnancy is the time pre-eclampsia can strike. Watch out for its symptoms and call your midwife or GP in case you have any of them for
medical advice. Symptoms for pre-eclampsia during pregnancy includes: 

  • High blood pressure
  • Problems with vision
  • Severe pain under ribs
  • Rapidly increasing swelling of the face, hands or feet
  • Strong headache or heartburn that don’t go away with usual medicines

Choose your week: 

Find out more by choosing how far gone you are... 

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  • Author: Emily Thorpe Emily Thorpe
  • Job Title: Digital Writer

Having written for Mother&Baby magazine for four years where she wrote news, product pages, features and interviewed celebrities such as Paloma Faith and Fearne Cotton, Emily now works as Digital Writer for Mother&Baby online where she specialises in travel and product reviews.