Pregnancy trimesters

An Overview of the Pregnancy Trimesters

October 17, 2018
8 min read

Being pregnant is an unforgettable experience for every mom-to-be. As you make your way through each of the three trimesters of pregnancy, we'll introduce you to the changes and symptoms you're likely to encounter, as well as the many ways your baby will grow and develop. Read on for a breakdown of some of the highlights in your exciting journey — we can't wait to share what's coming up in each stage of pregnancy!

What's in this article:

The Stages of Pregnancy: The First, Second, and Third Trimester A Closer Look at the First Trimester A Closer Look at the Second Trimester A Closer Look at the Third Trimester FAQs at a Glance

The Stages of Pregnancy: The First, Second, and Third Trimester

A normal pregnancy is about 40 weeks long. The weeks are counted from the first day of your last menstrual period, which means an extra two weeks are counted at the beginning when you weren’t actually pregnant yet. A typical pregnancy is also actually about 10 months long, not the 9 months that most people think of. Your healthcare provider is more likely to refer to the weeks instead of the months. The weeks of pregnancy are also grouped into trimesters, each of which is about 12 or 13 weeks long. Here’s how the weeks of pregnancy are split into trimesters:

  • First trimester: weeks 1-13
  • Second trimester: weeks 14-27
  • Third trimester: weeks 28-42

Determining how far along you are in your pregnancy helps your healthcare provider check the progress of your baby’s growth, guides the timing of certain prenatal tests, and allows your provider to more accurately assess your pregnancy symptoms.

Your healthcare provider will assess when your baby is due, but you can get an approximate date using our Due Date Calculator tool. Keep in mind that though a typical pregnancy lasts about 40 weeks, most moms-to-be give birth in within about two weeks of their estimated due date.

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A Closer Look at the First Trimester

Congratulations — you’re going to have a baby! This is exciting news and we’re happy for you. Although it’s still too early to find out whether you’re having a little boy or girl, that doesn’t mean you can’t have a little fun guessing! What does our quiz tell you? Are you having a boy or girl?

Your Baby’s Development

In the first few weeks, all the things your baby needs to grow in the uterus will form, including the placenta, the umbilical cord, and the amniotic sac that will fill with amniotic fluid. Starting off as a bundle of cells, your little one will soon begin to develop a spine; the major organs such as brain, heart, and lungs; basic facial features like the nose, eyes, and mouth; and buds that will grow into arms and legs. Your baby's skin will still be thin and transparent at the end of the trimester, but will soon thicken, and soft nails will also begin to grow.

Although your baby’s muscles will begin to develop and your little one will be able to move, it’s still too early for you to feel these flutters yet.

First Trimester Symptoms

Some of the early signs of pregnancy include:

  • Morning sickness. This is a well-known symptom during the first stage of pregnancy; however, contrary to its name, morning sickness doesn’t necessarily strike only in the morning. Not all women experience these queasy feelings; for those moms-to-be who do, the nausea and sometimes vomiting often crops up between week 4 and week 9 of pregnancy and goes away early in the second trimester. If you do have morning sickness, there are some things you can try that might help you feel better. For example, keep hydrated, try eating bland foods like toast and bananas, eat small meals more frequently throughout the day, and avoid smells or foods that make you want to vomit. You could also ask your healthcare provider for recommendations on what’s right for you.
  • Spotting. Early in the first trimester you might notice some spots of blood on your panties. This spotting could be implantation bleeding, which happens when the fertilized egg attaches to the lining of the uterus. If you notice heavier bleeding in the first trimester, or at any time during pregnancy, contact your healthcare provider.
  • Mood swings. You may find your mood changes from one moment to the next, and you might have different feelings than you had expected. It’s natural to go through a range of emotions, from the joy of knowing that you’ll soon become a parent to anxiety about the responsibilities and lifestyle changes parenthood demands. You might even feel frustrated with the physical symptoms you’re experiencing. Mood swings can be totally normal, and it might help to speak to your loved ones about how you’re feeling. If your mood swings seem severe, ask your healthcare provider for advice.
  • Weight changes. Both gaining weight and losing weight can be normal in the first trimester. If you have severe morning sickness you may find it hard to keep food down, resulting in a little weight loss. Although experts typically recommend gaining weight steadily, you may find that you put on most of the pounds in the second and third trimesters, and only gain a little in the first trimester. Ask your healthcare provider about what’s right for your situation.

Things to Keep in Mind for This Trimester

  • Healthcare. Look into what healthcare services are available to you during pregnancy, and select a healthcare provider if you haven't done that yet. You can read more about finding a good prenatal healthcare provider here.
  • First prenatal visit. At your first prenatal care visit your doctor may schedule any first trimester screening tests or scans. This appointment is a good opportunity for you to ask any questions or raise any concerns you have. Your provider may also make some recommendations, including taking supplements such as folic acid, adjusting the medications you take, or giving advice on healthy lifestyle changes.
  • Announcing your pregnancy. When to tell people you are pregnant is a personal choice. Many moms-to-be wait until the second trimester, when the risk of miscarriage is lower, but the choice is yours.
  • Maternity leave. If you work, you may be eligible for some paid or unpaid leave during and after pregnancy. Find out what rights you have, including under your state’s laws. Some workplaces also offer additional benefits. You should also research when you’ll need to tell your employer about any leave you’ll be taking, and whether you need to complete any additional paperwork.
  • Find out much more about the first trimester here.

A Closer Look at the Second Trimester

If you experienced some uncomfortable symptoms in the early stages of pregnancy, you may be wondering “when will the first trimester be over?”. The good news is, you may find the second trimester, which starts at week 14, much more enjoyable than the first! This is sometimes called the “honeymoon period,” when some pregnancy symptoms subside and many moms-to-be experience a surge in energy.

Your Baby’s Development

Your baby is busy in there! During this trimester your little one will begin to hear sounds and will even respond to loud or familiar sounds. A waxy coating called vernix will cover the skin, protecting it from the fluids in the amniotic sac. Downy hair called lanugo will grow all over your baby’s body — in fact, some babies are even born with patches of lanugo. By the end of this trimester your baby’s fingers and toes will be completely formed, and your little one will have unique fingerprints! You’ll be able to feel your baby kicking and stretching at some point in this trimester.

Towards the end of this stage your baby will start to grow more rapidly, including putting on more fat.

Second Trimester Symptoms

Although this is a much more comfortable time for many moms-to-be, there may still be some discomforts! For example:

  • Round ligament pain. Bands of connective tissue called round ligaments pull and stretch to support your growing uterus. As this happens, you may feel a dull ache or sharp pain on one side of your abdomen. To help relieve the pain, try changing positions, or, conversely, try not moving for a little while.
  • Headaches. If you experience mild headaches in the second trimester, try lying down with a cool pack on your head. If you experience a severe headache that just doesn’t seem to go away, tell your healthcare provider, as it could be a sign of something more serious.
  • Cravings. It’s quite common to crave certain foods during pregnancy. Give in to your cravings occasionally, but don't completely abandon your healthy eating habits. If you crave things like clay, starch, or chalk, definitely don’t eat them and contact your healthcare provider as it could mean you’re missing some nutrients.

Things to Keep in Mind for This Trimester

  • Feeling your baby move. At some point in this trimester you will start to feel your baby move. Each pregnancy is unique, so if you’re concerned about when you will feel a flutter for the first time, consult your healthcare provider. Once you’ve felt your baby move, there’s no need to obsessively worry about whether you can feel your baby move for the rest of your pregnancy, but you should let your healthcare provider know if you experience less movement than usual. A good way to keep track is to count 10 distinct movements in a two-hour period. For more on this, check out the Movement Tracker in our pregnancy guide.
  • Finding out your baby’s gender. Around week 20, your healthcare provider will likely schedule a mid-pregnancy ultrasound scan. During this scan, if you want to, you can find out the gender of your baby. Once you find out and are ready to share this news with family and friends, why not ask the host of your baby shower to include a special gender reveal moment?
  • Planning a babymoon. If you’re feeling good and are experiencing an energy boost, this could be a good time to take a vacation. Get the all-clear from your healthcare provider, and check out our guide to travel during pregnancy for tips and guidance.
  • Getting your home ready. Now could be a good time to start researching and organizing the things you’ll need for your baby, like furniture for the nursery, a car seat and a high chair, newborn clothes, and baby care essentials like diapers. You could also babyproof your home now to get these kinds of bigger jobs out of the way.
  • Prenatal exercise. If you haven’t already, add some gentle exercise to your routine, after checking in with your healthcare provider. Good options could include walking, swimming, and yoga.
  • Gift registry. Put together your gift registry, as the host of your baby shower may be needing it soon! Struggling with what to include? Take a look at our baby registry checklist.
  • Find out much more about the second trimester here.

A Closer Look at the Third Trimester

The third trimester starts at week 28 and ends when your baby is born! Your baby is considered full term at week 39. Once you’re in this stage of pregnancy, you’re in the final stretch, both literally and figuratively! Enjoy the last few months of pregnancy and use this time to rest and get ready.

Your Baby’s Development

During the past few months your baby’s eyes have been fused shut, but early in this trimester your baby will be able to open and close his eyelids and sense bright lights. Your baby’s brain is maturing rapidly and your little one is now better able to regulate his own body temperature, so he’s no longer relying on the amniotic fluid for this. Your baby’s bones are hardening, though his skull remains soft. Your baby may be gaining about half a pound per week and is putting on extra fat too, so his skin is less wrinkly by the middle of this trimester. As your baby grows, he won’t have as much room for somersaults, but you’ll still feel your baby kicking and maybe even hiccupping. Toward the end of this trimester, your baby will have dropped lower into your pelvis in preparation for birth. By week 40, many babies weigh between 6 to 9 pounds and measure 18 to 20 inches long.

Third Trimester Symptoms

  • Feeling short of breath. As your uterus grows and presses up towards your lungs, you may feel short of breath. Practicing good posture may help you fill your lungs more easily, but you could also try to rest more often to catch your breath.
  • Itchy skin. As your skin stretches over your growing belly and breasts, you may find it becomes very itchy. Try staying hydrated and using a moisturizer morning and night.
  • Braxton Hicks contractions. It’s normal to have “practice” contractions, known as Braxton Hicks contractions, that come at random intervals, or when you move suddenly. These contractions don’t actually mean you are going into labor. But, if your contractions become regular or more painful over time, or if you’re at all unsure about whether you’re feeling practice or true labor contractions, contact your healthcare provider right away.

Things to Keep in Mind for This Trimester

  • Prenatal classes. Register for and attend a course to help you feel more prepared for what's ahead. Ideas include classes on childbirth, infant CPR, breastfeeding, or baby care. Read more about how to choose a childbirth class here.
  • Birth plan. If you’re thinking of having a birth plan, consider what you’d like to include and discuss it with your healthcare provider. Read about what you could include in your birth plan here.
  • Hospital tour. If you plan to give birth in a hospital, ask if you can take a tour. This will give you a chance to familiarize yourself with the best place to park the car and the quickest route to the labor ward. This could also be a chance to ask any questions you have about hospital policies and paperwork, what you need to take with you, and what the hospital provides.
  • Hospital bag. Pack your hospital bag nice and early and have it ready to go. We’ve got you covered with our hospital bag checklist.
  • Baby names. Settled on a name yet? If not, don’t worry! There’s still time, and with our Baby Name Generator you’ll be able to create a shortlist of favorites.
  • Pampers Rewards. Download the Pampers Rewards app so that you can pick up fantastic coupons and gifts for all those diapers you’ll be buying.
  • Find out much more about the third trimester here.

FAQs at a Glance

What are the weeks in the trimesters of pregnancy?

The first trimester includes weeks 1 to 13, the second trimester lasts from weeks 14 to 27, and the third trimester goes from weeks 28 to 42.

How long is each trimester?

Each trimester is about 12 to 13 weeks long.

When is my baby full term?

By week 39 your baby is considered full term.

How accurate is my due date?

Only about 5 percent of moms-to-be give birth on their due date, which is just an estimate; most give birth in the two weeks before or after.

Now that you have an overview of the trimesters, for more detail on the stages of pregnancy take a look at our Pregnancy Calendar, where you can choose whether to get more info on a week by week, month by month, or trimester by trimester basis. There are so many exciting and interesting things happening during pregnancy and we’ve got you covered! Sign up to receive our regular emails so that you get relevant information direct to your inbox.



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All resources links
  1. ACOG: How Your Fetus Grows During Pregnancy

Book: Your Pregnancy and Childbirth: Month to Month, Sixth Edition Paperback – January 1, 2016
by American College of Obstetricians and Gynecologists (Author)

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