The Stages of Pregnancy: What to Expect for You and Baby

You're staring at the two lines on a pregnancy test, and in an instant, your mind is racing with questions. For answers, you'll need to understand the stages of pregnancy, which helps you know what to expect for the next nine months.

First Trimester (Weeks 1 to 12): Laying Life's Foundations

The first trimester of pregnancy is a crucial period of development. While your body is working hard to support this new life, your baby’s main organs are forming, and their heart begins to beat—all before you have a visible bump.

Your baby’s development stages

Your baby begins as a single fertilized cell. This cell rapidly divides into a tiny cluster of cells, which then implants into your uterine wall and officially becomes an embryo. According to the American College of Obstetricians and Gynecologists (ACOG), the neural tube, which becomes the brain and spinal cord, forms in the first few weeks. By Week 6, a tiny heartbeat develops.

By the time you reach Week 9, your baby, now called a fetus, has distinct facial features like a nose and eyelids. Tiny limb buds have grown into arms and legs, complete with small fingers and toes. They even start to make small, spontaneous movements as their muscles and nervous system connect, though you won’t be able to feel them just yet.

Your body's early pregnancy symptoms

During these first 12 weeks, your body produces a surge of hormones. This causes many of the typical early pregnancy symptoms, like fatigue, breast tenderness, and morning sickness, which are positive signs that your pregnancy is progressing.

Second Trimester (Weeks 13 to 27): Senses and Connection

During the second trimester, you may feel your baby’s first kicks. This is a sign of their growing strength and developing coordination.

Your second trimester of pregnancy is often called the "golden period." Typically, your energy returns and many early discomforts fade. You’ll begin to see a belly bump as your baby grows bigger and learns to move and hear.

Your baby’s sensory awakening

Baby development in the womb becomes much more tangible during these weeks. Your baby's skeleton is hardening, and their body is growing rapidly. Around Week 18, you may feel those first magical flutters of movement, known as quickening.

Your baby’s senses are also coming alive. Their taste buds are developing, and their ears are now fully functional. They can also hear your voice, your heartbeat, and other sounds from outside.

A review in Frontiers in Psychology found that babies not only hear sounds in the womb but also form early memories of it, reacting to that familiar noise after birth. Now is the time to start talking, singing, or reading to your little one to build an early bond.

Your changing body and growing bump

As your baby grows, so will your belly, and your clothes will start to feel snug. You might also experience mild, irregular cramping called Braxton Hicks contractions, which are your body’s usual way of practicing the real thing. 

Third Trimester (Weeks 28 to 40): Preparing for the World

During the third trimester of pregnancy, your body begins to prepare for delivery as your baby gains weight.

Your baby’s final weeks of development

Your baby’s brain has been developing at a rapid rate during these last weeks. Their eyes can now open and close, and they can perceive changes in light through the uterine wall. A layer of fat is building up under their skin, which will help them regulate their body temperature after birth.

You’ll feel your baby’s movements become stronger and more distinct as they practice breathing by moving their diaphragm up and down. Sometime during this trimester, most babies will settle into a head-down position. By Week 37, your baby is considered full-term and ready to meet you.

Your body in the final stretch

In the third trimester, your baby is getting ready for birth. Prepare your hospital bag so you’re ready for the big day, too.

You'll feel more physical effects, like back pain and heartburn, as your baby gains their final weight. A systematic review published in BMC Pregnancy and Childbirth found that low back pain affects 47.8% of expecting mothers during this period.

Heartburn also becomes more common as your baby takes up more space, states the American Pregnancy Association. Use this time to rest and prepare; finalize your birth plan, take a tour of the hospital, and get to the exciting task of packing your hospital bag.

Frequently Asked Questions

What if my pregnancy symptoms are different from what’s described?

Every pregnancy is unique, and so are the symptoms. Some people experience intense morning sickness while others barely feel it. The key is to focus on your overall health and to attend regular check-ups to ensure that you and your baby are healthy.

When will I feel the baby move for the first time?

Most first-time mothers feel the first flutters of movement, often called quickening, between Weeks 16 and 25. If this is not your first pregnancy, you might notice them a bit earlier. The feeling starts subtly, like a flutter or gas bubble, and will grow stronger and more distinct as your baby grows.

When should I call my doctor?

While many aches are a regular part of pregnancy, you should always contact your doctor if you experience:

• Heavy vaginal bleeding
• Severe abdominal or pelvic pain
• A high fever
• Painful urination
• A significant decrease in your baby's movement, especially in the third trimester

Understanding the stages of pregnancy makes the entire experience more meaningful. Every milestone, from the first heartbeat to the final kick, brings you one step closer to the little person at the heart of this journey.

Are you familiar with the stages of pregnancy? Join the ParentTeam Moms and Dads Facebook group and share your experiences with other parents.