The Three Trimesters of Pregnancy

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Question: How many trimesters are there in pregnancy and how is each trimester divided?

Answer: Each pregnancy is divided into three trimesters. Each trimester is roughly a third of your pregnancy. These three trimesters have different emotional and physical happenings that make them unique. Here is a guided tour through each trimester:

  • The First Trimester (Weeks 1-13)

    The first trimester is typically the shortest for you, because the first 3-4 weeks or more of your pregnancy, you do not even know you are pregnant. In fact, weeks 1-2 are the week of your last normal menstrual period, and when you ovulate. Most mothers won't be able to take a pregnancy test until around week four, and some are even later than that. This first trimester sees an incredible shift in your baby. She or he goes from being two separate things (sperm and egg) to having arms, legs, a beating heart, and so much more. The physical transformation of the mother's body is not outwardly as visible, but inside there is a lot going on.

  • The Second Trimester (Weeks 14-27

    This trimester is usually a time where you are feeling really good. The blahs of the first trimester and morning sickness are over for most mothers. The outward signs of pregnancy are beginning to show, which can be a lot of fun as you share the news of the pregnancy with others. Moms may also feel the baby move towards the middle of this trimester. While the baby is not drastically adding new features, the growth and extenuation of the previous growth is visible. Many families find out if they are having a boy or a girl in this trimester.
  • The Third Trimester (Weeks 28-42)

    The last trimester is always a bit of a guessing game. While most people are pregnant theĀ entire trimester, there is always the possibility that a mother will go a bit earlier in the safe window of the end of the third trimester. On the other hand, some pregnant people stay pregnant through the end of the third trimester's 42nd week. The outward signs of pregnancy become more obvious, and sometimes even comical. The stress of carrying a baby physically can weigh on a person, no pun intended. The baby is still growing and changing. We know that the last weeks see amazing growth in lung development, brain development, and even adding of brown fat, to help a baby stay warm after birth.

    Each of these three trimesters has their own unique personality. I like to think of the first trimester as a time to accept the pregnancy. There is a lot of emotional and mental work to do. The second trimester is a time to settle in and enjoy the pregnancy, bond with the baby, and begin to think of yourselves as parents.

    That final trimester is the time when a family really starts to prepare their world for the coming baby. This can be physical things or simply the emotional work that helps as a family adds a new person.

    Your doctor or midwife is one of the few people who will walk this entire journey with you. You will want to have a positive relationship with them to ask them the hard questions. They will use their expertise to help you make the best decisions that you can for each trimester and to give you a heads up as to what the next trimester will bring.


    Obstetrics: Normal and Problem Pregnancies. Gabbe, S, Niebyl, J, Simpson, JL. Sixth Edition.

    Becoming a Mom. March of Dimes. Last Access 22 January 2016.

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