What is the third trimester?
In your pregnancy’s third trimester, you and your baby undergo many bodily changes. These last three months of pregnancy can make you feel more tired and uncomfortable. But you’ll be ready to welcome a new member into your family.
Your third trimester will last from 28 weeks to 40 weeks of pregnancy. And it ends when you give birth to your baby. This 3-month period can be tiring and uncomfortable as your baby continues to grow in weight and size.
Changes you experience in the third trimester
Some symptoms and discomfort that you experienced in your second trimester may continue into your third trimester. As your baby begins to occupy more room in your womb, it puts pressure on your organs. You may have trouble breathing, and you may even have to go to the bathroom more often. But all these symptoms will go away once your baby is born.
You may experience the following during your third trimester:
- Acid reflux or heartburn and other digestive problems
- Trouble breathing
- Tender breasts
- Protruding belly button
- Varicose veins or spider veins
- Frequent peeing and difficulty sleeping
- Edema or swelling in your fingers, face, and ankles
- Increased body temperature
- Low blood pressure
- Leg cramps and lower back pain
- False labor or Braxton Hicks contractions
- Stretch marks on your abdomen, breast, thighs, and buttocks.
- Colostrum, or the first form of milk that nourishes your baby, leaking from the nipples
- Dry, itchy skin on the abdomen and skin pigmentation or dark patches on the face
- Vaginal discharge
Braxton Hicks contractions or false labor
Throughout your third trimester, you may experience irregular contractions that feel like cramps or tightening in your abdomen. These are false labor pains known as Braxton Hicks contractions, which last for up to 30 seconds. This is your body’s way of getting you ready for actual labor.
Between weeks 38 and 41 of pregnancy, you may experience true labor. Moms-to-be experience labor differently and may go into labor at different times. True labor has regular contractions that last longer than Braxton Hicks contractions and get stronger over time.
When you go into labor, your cervix opens up and uterus muscles begin to contract more frequently at regular intervals. These contractions will feel like intense cramps and may cause lower-back or abdominal pain. Your labor will last until you give birth to your baby.
Your baby in the third trimester
As your third trimester begins, your baby will be 4 inches long, weighing 2 to 4 pounds. Over the third trimester, your baby will grow to 18 to 20 inches long and weigh over 6 to 10 pounds at birth.
From 29 to 32 weeks of pregnancy
Your baby grows a lot during these few weeks as more fat is stored in its body. You will notice your baby kicking and fluttering inside more frequently, at least 10 times in 2 hours. The lanugo hair covering your baby during the second trimester continues to fall off .
Your baby’s bones are completely developed, but they are still soft and flexible. The eyelids now open and close. Eyelashes, eyebrows, and hair can be clearly seen on ultrasound.
At the end of 32 weeks, your baby will be 15 to 17 inches long, weighing about 4 to 5 pounds.
From 33 to 36 weeks of pregnancy
As you prepare for birth, your baby will slowly move into the head-down position. Your baby will grow more and rapidly gain weight. The lanugo hair will begin to disappear from the skin. Your baby’s skin starts to appear plump and fuller than it appeared in the second trimester. And the protective waxy coating called vernix that forms in the second trimester gets thicker.
Your baby's developing brain allows it to listen, feel, and somewhat look inside your womb. The eyes can now sense light as the pupils begin to constrict and dilate. The skull bones can move and overlap each other to help it pass through the birth canal.
At 36 weeks, your baby will grow to 16 to 19 inches and weigh 5.75 to 6.75 pounds.
From 37 to 40 weeks of pregnancy
Your baby is now full-term and ready to be born. The movement in your womb will slowly decrease as the baby becomes bigger. All organs develop and the fingernails grow longer. Small breast buds grow under the chest where the nipples will develop.
Your body supplies your baby with antibodies through the placenta. This helps your baby’s immune system fight against diseases after birth.
The vernix and lanugo completely disappear. Your baby’s sex organs will have completely developed by this stage. As your due date approaches, your baby will likely move into the head-down position for birth.
Your baby is now 19 to 21 inches long and weighs 6.75 to 10 pounds.
Your newborn baby’s head may look unevenly shaped after passing through the birth canal. The baby may be covered in some vernix and blood. Its skin may be discolored or dry and have rashes.
Here are some tips for self-care during the third trimester:
- Drink lots of water.
- Schedule prenatal visits or third-trimester tests at least every 2 to 4 weeks to check on your baby’s health.
- Have healthy food and supplements for adequate energy and nutrients.
- Exercise regularly, but don’t tire yourself.
- Consult your doctor for diet and lifestyle advice to prevent heartburn and other digestive symptoms.
- Use a pillow to support your body to help ease tension while resting or sleeping.
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Health Solutions From Our Sponsors
ACOG: "How Your Fetus Grows During Pregnancy."
American Pregnancy Association: "Third Trimester of Pregnancy: Fetal Development."
KidsHealth: "A Week-by-Week Pregnancy Calendar."
OASH: "Stages of pregnancy."
pregnancybirth&baby: "Braxton Hicks contractions."
Summa Health: "3rd Trimester."
unicef: "Your third trimester guide."
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