Pregnancy Trimesters
Pregnant Stages: The Three Trimesters


Woman in her second trimester

Pregnancy Trimesters


First Trimester: Week 1 to 12
Second Trimester: Week 13 to 27
Third Trimester: Week 28 to 40

All About Pregnancy
See our overview:
Pregnancy Guide

What Are Trimesters?

Pregnancy lasts about 40 weeks if dated from the first day of your last period. Those 40 weeks are divided into three periods called trimesters. Each trimester lasts about 3 months. The changes that occur within a woman’s body and the development of the baby at each stage of pregnancy and trimester are fairly standard. Your doctor or OB/GYN will talk you through those stages as well as give you a prenatal care guide. Meantime, here is an overview of what to expect.

First Trimester: Week 1 to 12

The first twelve weeks or first trimester of pregnancy can be busy! It starts with putting your pregnancy team in place and choosing the OB/GYN, and then the first of the prenatal visits begin, the first ultrasounds, deciding which prenatal vitamins to take and looking at options for prenatal birthing classes. Meantime your body is changing, your hormones are all over the place and a little baby is on the way.

What Will Happen to You

Morning Sickness: technically called 'morning' but it can happen throughout the day. The cause is not known, but it may be linked to high levels of pregnancy hormones. Morning sickness can start as early as week 2 and continue for most of the first trimester.
• Breasts will become tender and start to grow as milk glands begin to multiply. See pregnancy breast changes.
• Extreme tiredness: your body is using a lot of energy.
Pregnancy cravings and aversion to certain smells.
Constipation in pregnancy is common in the third trimester, as well as diarrhea.
• Need to urinate more often.
• Headaches.
• Mood swings: hormones are going a little wild.

Fortunately many of these pregnancy symptoms disappear as the trimester progresses - and some women are fortunate not to even experience them at all. If you have been pregnant before, just because you experienced a rough first trimester in your last pregnancy, does not necessarily mean you will in the next one. If you have a spare moment, do check our Childbirth Guide, the more you learn now, the longer you have to consider your options.

What Will Happen to Baby

• Your baby will develop from a tiny blip of a few cells to about 8-9cm in length. The placenta is fully formed by the end of the first trimester of pregnancy and the embryo becomes known as a fetus.
• The baby's brain, eyes, ears, fingers, toes and vital organs will begin to grow. The eyelids are still sealed shut.
• The baby's genitals will start to form, so that by the end of the trimester, you could know the gender.

Second Trimester: Week 13 to 27

The most exciting milestone of the second trimester of pregnancy is when you feel your baby move for the first time. This can happen any time from the fourth week onwards. The second trimester is usually the most enjoyable period of pregnancy because you are still small enough to move around comfortably and many of the earlier symptoms of pregnancy such as morning sickness have disappeared. This is likely to be the first time you consider buying maternity clothes. You might find this useful: When should I start wearing maternity clothes?

What Will Happen to You

• You start to look pregnant as your belly becomes rounder. Pregnancy weight gradually increases.
• Your breasts continue to grow in size. You may start to ask how early does nipple discharge start in pregnancy?
• You may start to retain water, so your fingers, ankles and legs feel a little swollen.
• Freckles and moles may become a little darker.
• You may get backaches, hip, groin or pelvic pains and your posture can change as your baby grows.
Stretch marks and/or varicosities (varicose veins in pregnancy) may appear across the stomach, breasts, thighs or buttocks.

What Will Happen to Baby

• This is the first time you are likely to feel your baby move and typically it happens in the fourth month. However, it may be that you do not feel the flutter of movement until much later, this is not uncommon.
• The baby's bones become harder and ears begin to look like real ears.
• A fine layer of hair, called lanugo covers the baby’s body until birth.

Third Trimester: Week 28 to 40

The end of the journey is finally approaching! Some of the discomforts you suffered in the second trimester can continue and may even become more difficult. During the third trimester of pregnancy:

What Will Happen to You

• Shortness of breath, but this eases after the baby drops.
• Feeling the need to urinate more frequently.
• Heartburn.
• Swelling.
• Weight gain.
Hemorrhoids in Pregnancy.
• Sensitive gums.
• Leg cramps at night.
• Frequent Braxton Hicks contractions.

What Will Happen to Baby

• The baby's lungs develop, so that by week 32 he or she is more likely to survive if born prematurely.
• Fat stores are laid down in preparation for birth.
• Fingernails and fine hair on the head grow.
• The eyes open and some teeth may even start growing under the gums.

Related Articles

How much weight should I gain during pregnancy?

  Related Articles on PREGNANCY

For more about what to expect while pregnant, see the following:

Prenatal Tests - Regular scans and 4D scans.
Waterbirths at Home - At Birthing centers or under midwife care.
Home Birth Options - Alternative childbirth.

Back To Homepage: Womens Health Advice

Please Note: Information provided on this site is no substitute for professional medical help. See Disclaimer.
Copyright. All rights reserved.