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Third Trimester

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The third trimester is the last phase of pregnancy. This article explains the changes that a mother may undergo during this phase.

Written by

Dr. Asha. C

Medically reviewed by

Dr. Nikitha Murthy

Published At May 26, 2022
Reviewed AtDecember 12, 2022

When Does the Third Trimester Begin?

The third trimester is the last phase of the pregnancy that begins around week 28 of pregnancy and lasts until giving birth, which may be around week 40 of pregnancy or months 7 to 9 of pregnancy. During the third trimester, the fetus grows, develops, and starts to change its position to get ready for birth.

What Are the Changes in the Mother’s Body During the Third Trimester?

Backache -

Back pain is due to the pregnancy hormones relaxing the connective tissue that holds the bones in place in the pelvic area, and the extra weight gained also adds pressure on the back. To ease the back pain, try to practice good posture, sit up straight, choose chairs with good back support, sleep on the sides with a pillow tucked between the legs, wear low-heeled and comfortable shoes, get regular exercise, and use a heating pad to reduce pain. If the pain is severe or persistent, contact your healthcare provider.

Braxton-Hicks Contractions -

During this period, mothers start to feel mild contractions, which are actually warm-ups to prepare their uterus for actual labor. Braxton-Hicks contractions are not as intense as real labor contractions. They are more likely to occur during the afternoon or evening, after sex, or after physical activity. If the face becomes red and out of breath after the contractions, or if the contractions are regularly occurring, reach out to your physician immediately.

Breast Enlargement and Leaking -

The breast grows as much as two pounds by the end of the pregnancy. Wear a supportive bra, to give good back support. There will be a discharge of yellowish fluid from the nipples by the end of the pregnancy. This is called colostrum which will nourish the baby in the first few days after birth.

Frequent Urination -

As the baby grows bigger and moves deeper, its head may be pressing down on the mother's bladder. This extra pressure causes frequent urination. Urination leak can happen during coughing, sneezing, laughing, or while exercising. To resolve this problem, one can use panty liners, use the bathroom whenever you feel the urge, and try to dry out the bladder entirely.

Heartburn -

Pregnancy hormones relax specific muscles, including muscles present in the esophagus. This can allow stomach acid to reflux into the esophagus and cause heartburn. Eat small, frequent meals and avoid greasy foods, citrus fruits, chocolate, and spicy or fried foods to relieve heartburn.

Shortness of Breath -

During the third trimester, the uterus expands and sits just under the rib cage, making less room for the lungs to grow; this pressure causes difficulty in breathing. Doing yoga and breathing exercises can help with shortness of breath.

Fatigue -

Tiredness during the third trimester is commonly expected to be on peak, compared to the rest of the trimester. As the growth of the baby increases than the first trimester, carrying around that weight will cause exhaustion and fatigueness. Eating healthier meals, supplementing with iron and proteins shall help reduce the fatigueness.

Hemorrhoids -

These are swollen veins that form around the anus. Increased blood supply and pregnancy weight increase the amount of pressure on the area. To ease the itch and discomfort caused due to hemorrhoids, try sitting in a warm tub or sitz bath.

Stretch Marks -.

Stretch marks happen when the skin stretches during pregnancy. It may develop on the breasts, tummy, butt, or thighs.

Weight Gain -

By the end of the third trimester, the mother has the possibilities to have gained 25 to 35 pounds. The extra pounds comprise the baby's weight, amniotic fluid, placenta, increased fluid, blood volume, and added breast tissue.

What Are the Developments in the Fetus During the Third Trimester?

The fetus grows in size and weight during the third trimester. The fetus starts to move and position itself head-down. By the end of the third trimester, the fetus weighs about 6 to 9 pounds and is 19 to 21 inches long.

Fetal development during the third trimester includes:

  • The brain continues its development.

  • The lungs continue to mature by 38 weeks to 40 weeks, the lungs will be developed fully.

  • The fetus can hear and see.

  • The head may drop into the pelvic area by the 36th week. This process is called lightning.

  • The cartilage transforms to bone in the 7th and 8th month. The bones of the skull will be soft to make it easier to pass through the birth canal.

  • In the third trimester, the baby's brain will grow faster than ever where it develops skills including dreaming, blinking, and regulating body temperature.

  • During the final weeks of pregnancy, meconium (baby's first poop) starts to build up in the baby's intestines.

  • By 38 to 40 weeks, the fetus' lanugo (the warm, hairy coat) has almost gone away.

  • The head will often turn downwards during the last two weeks of pregnancy.

What Are the Warning Signs in the Third Trimester?

The mothers may experience false labor symptoms as the expected delivery date approaches. The symptoms of labor pain include:

  • In the 36th week, waddling may happen as the baby drops into the pelvis.

  • A pink or brown mucus with blood is a sure sign that indicates labor is on its way. Some mothers may or may not notice the mucus plug discharge (which seals off your uterus).

  • Sharp cramps in the groin area can be a sign of labor as the cervix starts to dilate and thin out.

  • Labor Contractions - As compared to Braxton-Hicks's contractions, actual labor contractions intensify rather than diminishing when the mothers move around.

  • Water Breaking - The amniotic sac will rupture in some mothers, which experiences a slow and steady fluid trickle, requiring immediate hospitalization.

If there are any signs of preterm labor or any following symptoms, consult the physician immediately,

  • Heavy vaginal bleeding.

  • Severe vaginal pain.

  • Severe cramping pain in the lower abdomen.

  • Severe vomiting.

  • Sudden weight gain.

  • High fever.

  • Severe dizziness.

  • No baby movements.

  • Pain or burning sensation during urination.

What to Avoid During the Third Trimester?

These are a few things to avoid in the third trimester.

  • Traveling - If the due date is nearing, it is a good idea to avoid traveling.

  • Lying on the Back. - Avoid lying flat on the back during pregnancy because the entire weight of the baby and uterus compresses the vein to the heart, causing nausea and shortness of breath.

  • Hot Tubs and Saunas - Avoid hot tubs and saunas because it raises the internal temperature. Keep the water at normal temperature during the bath, and avoid losing balance while bathing.

  • Exercising in Warm Temperatures - Stay indoors to reduce overheating or becoming dehydrated.

  • Raw or Undercooked Foods - Raw and undercooked foods can bring bacteria, so avoid them during pregnancy.


The third trimester of pregnancy can be uncomfortable and tiring when the long wait is over, and the baby is expected to arrive soon. The mothers should be cautious about the signs of labor like pregnancy contractions, fluid leaks, etc., and be prepared for immediate hospitalization.

Frequently Asked Questions


How Much Sleep Is Required During the Third Trimester of Pregnancy?

The third trimester is the most challenging time of pregnancy due to back pain, growing belly, and kicks at odd hours. So at least 8 to 10 hours of sleep is necessary to feel comfortable. If the mother feels sleepy during the middle of the day due to a poor night's sleep, taking a nap will be helpful.


Why Is the Third Trimester Very Important?

The third trimester is very important because full development of the baby’s brain and vital organs such as eyes, lungs, heart, intestinal system, immune system, and kidneys takes place in this stage of pregnancy. Additionally, only in the third trimester does a high placental transfer of important nutrients required to support the baby through the first six months of life take place.


Is It Required to Take Folic Acid During the Third Trimester?

Women who are pregnant or trying to become pregnant should get at least 400 micrograms of folic acid daily before becoming pregnant and for at least three months afterward to prevent congenital disabilities. And it is not necessary to take folic acid after that.


How Much Weight Will Be Gained During the Third Trimester?

Usually, there will be more weight gain in the second and third trimesters. This is because the breast size, blood volume, and water retention increase. Additionally, the baby and placenta also grow rapidly in these stages. As a result, women are expected to gain around 0.5 to 1 lb per week during the third trimester.


What Should Be Done During the Third Trimester of the Pregnancy?

The essential thing to be considered during the third trimester is the following:
- Being aware of the pregnancy symptoms that should never be overlooked.
- Always be aware of the baby's movement.
- Eat a healthy diet.
- Do some exercises and stretches.
- Massaging the bumps makes you feel close to the baby.
- Know about the stages of labor.
- Interact with the baby.
- Talk to your doctor about your queries and wishes.
- Buy clothes for your baby.
- Pack the hospital bag.
- Get adequate rest and sleep.


Does Hunger Increase During the Third Trimester?

Usually, pregnant women experience less appetite, and the cravings also disappear in the third trimester. This is because of the pressure of the growing baby on the abdomen, which makes less room for food. Therefore, it is recommended to eat small meals every few hours.


Is Prenatal Visits Important in the Third Trimester?

In the third trimester, there will be prenatal visits every two weeks until week 36. After week 36, there will be prenatal testing every week. These visits are very important.


What Are the Tests Done During the Third-Trimester Prenatal Visit?

- Blood pressure and weight are checked.
- The urine sample may be checked for sugar, protein, and infection.
- The baby's heartbeat is checked using a Doppler.
- The fundal height (the distance between your pubic bone and the top of your uterus) is measured.
- A third-trimester ultrasound is done to evaluate the growth and the amniotic fluid levels.
- The doctor may also check the ultrasound if they are not sure about the position of the baby from an abdominal exam.


How Many Scans Are Needed During the Third Trimester of Pregnancy?

The number of ultrasounds depends on the health and condition of the mother and the baby.
- In high-risk pregnancy, the doctor will offer additional scans during the third trimester of the pregnancy, performed at weeks 28, 31, 34, 37, and 40 of pregnancy.
- In moderate-risk pregnancy, doctors will offer three additional scans during the third trimester at 32, 36, and 40 weeks.
- In moderate to low-risk pregnancy, the doctors will offer two additional scans at 32 and 36 weeks of pregnancy.


When Should I Be Worried About the Third Trimester of Pregnancy?

Pregnant women should immediately consult a doctor when any following symptoms occur during the third trimester of pregnancy.
- Vaginal bleeding.
- Amniotic fluid leak through the vagina.
- Decreased baby movement.
- Fever.
- Severe headache that does not go away.
- Severe abdominal pain or cramps.
- Severe back pain.
- Sudden and severe swelling of the hands, fingers, or face.
- Decreased urine output.
- Continuous vomiting or nausea.


When Does the Third Trimester Begin?

The third trimester of the pregnancy starts from 28 weeks to 40 weeks. Seven, eight, and nine months come under the third trimester. The baby continues to grow fastly, and its vital organs develop during this period.


Is Tiredness Normal During the First Trimester of Pregnancy?

It is normal to feel tired and exhausted during early pregnancy. Fatigue is an early sign of pregnancy; most women experience it in the first trimester. Tiredness is also common in the third trimester; more than 60 percent of all pregnant women experience it.


What Discomfort Can Be Experienced During the Third Month of Pregnancy?

The level and the type of discomfort differ from one woman to the other, which include:
- Lower back and hip pain.
- Vaginal pain.
- Abdominal cramps.
- Swelling of the legs.
- Insomnia.
- Feeling full faster and decreased appetite.
- Breast pain.
- Frequent urination.
- Dizziness and lightheadedness.


Why Is the Third Trimester of Pregnancy Very Hard?

The third trimester of pregnancy can be emotionally and physically challenging. It is mainly due to the growing baby's size and position that might make it hard to get comfortable. Additionally, the symptoms associated with the third trimester make it even harder.


Why Does the Pain Occur When the Baby Moves?

During the third trimester, a mother can experience pain or discomfort in the tummy, ribs, or vagina when the baby moves around due to the baby’s strong and fast growing muscles and powerful movements.


How Much Growth Can Happen in the Third Trimester?

The third trimester is when the baby's weight increases and the vital organs mature so they can readily function after birth. The fetus will weigh about 6 to 9 pounds and grow about 19 to 21 inches long during the third trimester of pregnancy.


What Kind of Exercise Is Recommended During the Third Trimester?

- Walking will be a great exercise; it is an easy and quick cardio activity.
- At-home exercises like squats, leg lifts, lunges, and arm lifts can tone the muscles during pregnancy. It is recommended to do exercise for at least 30 minutes a day.
- Pelvic floor exercises.
- Yoga.
Dr. Nikitha Murthy
Dr. Nikitha Murthy

Obstetrics and Gynecology


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