We have updated our Online Services Terms of Use and Privacy Policy. See our Cookies Notice for information concerning our use of cookies and similar technologies. By using this website or clicking “I ACCEPT”, you consent to our Online Services Terms of Use.
OB/Gyn & Women's Health Services

What to Expect: The 3 Trimesters of Pregnancy

Your pregnancy is made up of three trimesters, each one lasting roughly three months. Your body will go through many different changes during your pregnancy as your baby grows and develops. Learn more about what happens to you and your baby during each of the three trimesters.

First Trimester

Your baby grows exponentially during the first trimester, beginning as a small clump of cells and growing into a fully formed fetus with body structure and internal organs and systems in a relatively short period of time. A crucial time of development, birth defects and miscarriage are more likely to occur now than in later trimesters.

Your body will undergo many changes as well, and many early pregnancy symptoms may begin to show up early in your pregnancy, maybe before you even know you’re pregnant. These includes nausea (“morning sickness”), fatigue and breast tenderness. You may experience some or none of these symptoms; every woman and every pregnancy is different.

Second Trimester

The second trimester is a time of rapid growth for babies and by the end of the second trimester (around week 26) your baby can weigh 2-3 pounds. Baby will develop defined fingers and toes and may start to hear sounds. The sex of the baby will also become apparent during the second trimester, and you may begin to feel the first fluttering movements sometime after 16 weeks.

Many women find the second trimester to be a golden period of pregnancy as the symptoms of the first trimester begin to recede. However, you may start to experience new symptoms – such as heartburn, constipation and back pain – as your baby continues to grow. Many women don’t gain much weight during the first trimester, but during the second trimester you can expect to start gaining 1 to 2 pounds a week.

Third Trimester

Your baby’s internal systems continue to mature during the third trimester, and the baby will rapidly increase in size and weight. The baby will begin to stretch and kick, practice breathing, and will be able to detect light. After about 31 weeks, most of the baby’s development is complete; he now begins to rapidly gain weight, going from around 2 pounds at 27 weeks to 6.5 to 10 pounds by 40 weeks.

Your baby’s increase in size may cause some discomfort as you grow bigger too. Symptoms may include shortness of breath, hemorrhoids, trouble sleeping, urinary incontinence, pelvic pain, and swelling in the feet and legs. You may also have more trouble moving around with your expanding belly. These symptoms may get worse the closer you get to your due date – but they should all go away after your little one’s arrival.