28 July, 2020

The Four Pregnancy Trimesters: And What To Expect

pregnancy trimester, pregnant

You’ve probably heard that women are pregnant for nine months, but then there’s all this talk of how many ‘weeks pregnant’ you are. Then you’ll hear about pregnancy trimesters and reaching the wondrous ‘dream trimester’ – and it all starts to become a little mind-boggling! Well, our in-depth guide will explain what to expect at the beginning of each trimester and even dive into the mysterious fourth trimester, which doesn’t get nearly as much airtime as the previous three – but is equally as important!

What is a pregnancy trimester?

A woman’s pregnancy can be split in a few different ways to describe and categorise the whole pregnancy from conception to birth. One of these ways is in months, with the average pregnancy lasting nine months, and an average of 40 weeks. The third way a pregnancy is categorised is with trimesters. These are formed by the grouping together of weeks to form trimester one, two, three (and four!). Each trimester is made up of roughly 12-13 weeks.

Why does each pregnancy trimester differ?

At the beginning of each trimester, there are a number of symptoms women can experience at some point during that 12-13 week period. Likewise, there are a number of growth changes and milestones that both mum and bub could encounter during each trimester, and it’s these changes that help to give each trimester a globally recognised ‘persona’.

What happens during the first trimester, aka the ‘secretly sick’ trimester

(week 1 – to the end of week 12)


This trimester is considered the hardest for a number of reasons. The first being that many women decide to keep their pregnancy secret until they hit the 12-week mark, as the rate of miscarriage drops sharply at that time. An influx of estrogen and progesterone during those first 12 weeks of pregnancy means that a woman’s body is thrown seriously out of whack. In fact, a woman will produce more of these hormones during one pregnancy than she will in her entire life when not pregnant. With that in mind, it’s no surprise that symptoms such as morning sickness are heavily prominent during that time as your body attempts to cope with and level out the surge of new hormones. Along with nausea, exhaustion and dizziness are incredibly common side effects of an excess of hormones in the body, which is why it’s often to hard to hide the way you’re feeling from friends, family and co-workers. Food aversion may also affect you, so it’s important to work out at this time what is safe for you to eat and which healthy foods you can stomach. Maybe beginning to plan the nursery can get your mind off that smell… because odds are with your heightened senses, if something’s a little whiffy – you’ll smell it.

First Trimester Symptoms and Changes:

  • Nausea
  • Dizziness
  • Fatigue
  • Loss of appetite
  • Baby begins to sprout arms, legs, feet, hands by around week 6 – and fingers and toes by week 10.
  • By around 9 or 10 weeks, you should be able to hear baby’s heartbeat.
  • By week 8 your baby will have taste buds!

What happens during the second trimester, aka the ‘dream’ trimester

(week 13 – to the end of week 26)


By week 13, generally the level of hormones in a woman’s body has stabilised substantially, and many women report the uncomfortable symptoms they experienced over the last 12 weeks have lessened considerably. It’s for this reason that the ‘dream trimester’ is widely considered the most enjoyable part of the pregnancy for many women. However, just because you’re feeling better, doesn’t mean things are slowing down, in fact, your baby grows considerably during this trimester, and it’s more than likely the time in which you’ll see your belly ‘pop’ and begin to feel your first kicks! Excitingly, the second trimester also sees your baby’s organs become fully developed and he or she will even soon be able to hear! Likewise, the movements that a pregnant woman can feel aren’t just kicks. As the baby grows stronger during the later half of the second trimester, many women will be able to feel their baby moving around considerably, following wake and sleep cycles like we do. Time to book a babymoon before some of that dreaded third trimester exhaustion kicks in!

Second Trimester Symptoms and Changes:

  • Body aches
  • Increased appetite
  • Stretch marks on stomach, breasts and thighs
  • Skin changes, such as darkening of the skin
  • Swelling of the extremities
  • Itchy skin
  • Baby can kick and begin to move side-to-side
  • Baby’s scalp hair pattern is forming
  • Around week 14, baby’s genitals start to form.

What happens in the third trimester, aka the ‘uncomfortable’ trimester

(week 27 – to the end of pregnancy)


By the time you reach week 27, you’re well and truly on the home stretch. For most women, their belly is becoming increasingly bigger as each week passes, and with that increase in size, comes an increase in discomfort. The discomfort can come in many forms, but many women report added pressure on their bladder over the course of the third trimester, which aside from being uncomfortable, can result in the frequent feeling of needing to urinate. This can seriously disrupt a woman’s sleep in the third trimester – and it’s not the only thing that can leave a woman wide-eyed at 2am. ‘Pregnancy insomnia’ can occur at any point in a pregnancy, but is often experienced in the third trimester, due to not being able to get comfortable, pre-baby anxiety, those pesky pregnancy hormones and as mentioned, multiple nightly trips to the loo!

It is also widely recommended that a pregnant woman refrain from sleeping on her back and obviously her front – with the left side being the preferred sleeping position. That leaves a heavily pregnant woman with one option to try and get comfortable each night, add to that the 3am party baby is having inside her belly, and you can bet that 12-hours of shut-eye are already a thing of the past. Also during this time (around the 36 week mark) the baby will likely ‘drop down’ toward your pelvis into birthing position, getting ready to enter the world. This is called ‘lightening’ and is actually one of the early stages of labour. Your physician will be able to clarify the baby’s position and work out a suitable birthing plan for delivery. From 37 weeks your baby is actually considered ‘fully baked’ and could show up any time, so be ready!

Third Trimester Symptoms and Changes:

  • Fatigue
  • Braxton Hicks (mild contraction-like tightness in your abdomen)
  • Shortness of breath
  • Backaches
  • Frequent urination
  • Mood swings
  • Pre-baby anxiety relating to birth
  • Baby’s bones are hardening (but the skull remains soft so that it can pass through the birth canal)
  • Baby’s liver and kidneys are fully functioning
  • Baby’s brain is continuing to develop

What happens in the fourth trimester, aka the ‘overwhelming’ trimester

(Birth – 12 weeks old)


The fourth trimester is classified as the first 12 weeks of a baby’s life after birth and is just as important as the previous three trimesters. This is the time when your baby leaves the safe, dark, quiet, and warm womb that protected them for the previous nine months, and has to face lights, smells, and sounds that they’ve never encountered before. While your baby’s brain is highly developed at birth, the neural pathways and nervous system continue to develop during this time. Your baby is like a sponge in the fourth trimester, soaking up every sensation and becoming more stimulated with each new experience. The more stimulated the brain, the stronger the connections in the brain become. During this time, your love, support and understanding are the things that will make this jump from the safe womb to the scary world more comfortable for your baby. They depend on you to respond to their cries and comfort them in their new surroundings. Likewise, it’s important to look after yourself too, by eating well, resting whenever possible – and leaving the washing for someone else to do!

Fourth Trimester Symptoms and Changes:

  • Gradually baby’s movements will become more controlled and less ‘startled’.
  • Baby will also begin to be able to sleep through noisy surroundings.
  • Your baby could suffer from reflux or colic, so watch out for lots of vomitting or long bouts of unexplained crying. Be sure to consult your doctor if either of these occur.
  • A few weeks into the fourth trimester, baby should begin to settle into more consistent sleeping and feeding patterns.
  • Knowing your baby will cry more in this period of life than any other period can help you to prepare yourself. Remember, love and comfort are key here in this new and scary big world!
  • Many people don’t talk about the first bowl movement post-birth. Depending on what occurred during birth (for e.g. whether or not you needed stitches) you may need to speak to your doctor about a medication that can help you pass stool smoothly.


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