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The Second Trimester: Your Baby’s Growth and Development

A mother in her second trimester shares a special connection with her first child, introducing them to their soon-to-be sibling.

After the exhaustion, fatigue and nausea of the first trimester, many pregnant people say that the second trimester is a much easier ride! By week 16-20, any lingering morning sickness has usually faded away.

This trimester is also exciting in that you start to LOOK pregnant – your tummy no longer looks simply swollen and bloated – but begins to round out as your uterus expands and your baby grows bigger.

So, let’s explore what’s going on for your baby in weeks 13-27 – the second trimester!

The Second Trimester: your baby’s development

  • Your baby’s movement increases drastically. Most mothers will feel movement between weeks 16-22. Second time+ mothers feel their babies move a bit earlier than first time mamas. This first movement is known as “the quickening”.
  • The placenta is fully developed. Delivering your baby with all the nutrients they need to grow and thrive!
  • Eyebrows and eyelashes are starting to grow.
  • At the start of the second trimester, your baby is creating and passing urine.
  • If you’re expecting a girl, eggs will start to develop in her ovaries.
  • Taste buds and sensory neurons are developing. Your baby can taste and touch!
  • Around week 18, your little one will start being able to hear sounds inside your body like your beating heart.
  • Lanugo: fine, soft hair grows all over your baby’s body. It keeps your baby warm and protects their skin.
  • Baby’s skin is thickening and a greasy substance called ‘vernix caseosa’ coats their skin. This acts as a protective coating and provides lubrication, which is still seen at birth.
  • Around week 19 you may be able to find out your baby’s sex (if they cooperate) while the sonographer tracks your baby’s growth and development.
  • Your baby’s brain is undergoing rapid development, and they are experiencing sleep and wake cycles.
  • Baby starts to gain fat which will intensify more in the third trimester.
  • Hair is starting to sprout on your little one’s head. This may even be visible on an ultrasound!
  • Towards the end of the second trimester, your little one’s lungs are producing a substance called surfactant. This helps to keep the airways open and makes it possible for your baby to breathe once they are born.
  • Around week 27, your baby can start to open his eyes!
  • By the end of the second trimester your baby will likely be almost 2lbs (907g) and around 9 inches (230mm) long (crown-rump).



Onto the home stretch!

The second trimester is exciting and such an important time in your little one’s growth and development. As you look towards the third trimester – the home stretch – know that you are doing such an incredible job of growing your baby! It won’t be long now until you hold your precious little one in your arms.

Let’s dive into the third trimester and see what happens next!

Pregnant Mamas make sure you check out our FREE Prenatal class that 8 out of 10 new mothers say they wish they took before birth to ease their stress and worries. You can even watch it at your own pace from the comforts of your own home! Sign up here

It’s important to note that pregnancy should be discussed with a healthcare provider to ensure safety and suitability for individual circumstances. This blog is general education only. For any personal based advice regarding you or your baby please seek advice from your own healthcare professional.

  1. Department of Health & Human Services. (02-2012). Pregnancy - week by week. Better Health Channel.
  2. Fetal development: The 2nd trimester. (2022, June 3). Mayo Clinic.
  3. How your fetus grows during pregnancy. (December, 2021). ACOG.
  4. Professional, C. C. M. (March 3, 2023). Fetal development. Cleveland Clinic.
  5. Stages of pregnancy | Office on Women’s Health. (February 22, 2021).