Third Trimester of Pregnancy

Medically Reviewed by Dr. K on 21 April 2021

Table of Contents :

  1. Third Trimester of Pregnancy 
  2. New Fetal Development 
  3. Third Trimester Changes in Your Body 
  4. Red Flag Symptoms


Third Trimester of Pregnancy 


The third trimester of your pregnancy is the last stage of your pregnancy. It lasts for 29 weeks (or months 7, 8, and 9) and lasts for 40 weeks (or months 7, 8, and 9). Your baby grows, develops, and begins to change location in preparation for birth during this trimester. 


You’re in the home stretch of your pregnancy now that you’ve passed the third trimester. You just have a few weeks left, but this is the most difficult phase of your pregnancy.

You’ll find out what to expect during your third trimester of pregnancy in this article. You’ll learn which signs are common and which ones should be mentioned to the doctor.

New Fetal Development


Your baby continues to grow in the third trimester. A full-term baby is normally between 19 and 21 inches long and weighs between 6 and 9 pounds by the time it is born. 


To prepare for birth, the baby starts to transform itself head-down. The baby’s head can continue to migrate through your pelvic area about week 36, a process known as lightening. For the last two weeks of your pregnancy, it will be in this down-facing place. 


In the third trimester, the infant progresses in a variety of areas. At this time, it will be able to:

  • See
  • Hear
  • Suck on its thumb
  • Cry

Your baby’s brain is always growing. Its lungs and kidneys are fully developed. To make processing easier, the bones at the top of a fetus’s skull are delicate. At this time, most babies’ eyes are blue, and they’ll remain that way for a few days or weeks after they’re born. 


The vernix caseosa, a protective covering, covers your babies’ skin during the third trimester. The lanugo, a soft body hair, comes out and is almost gone at the end of week 40.

Third Trimester Changes in Your Body

  • Abdominal achiness. Your baby will take up more space in your womb as it develops. You can experience aches and pains as a result of this. When you’re going to sleep in the middle of the night, it may be difficult to get comfortable. You may also find it difficult to take deep breaths.

  •  Backache. Your back can feel achy and stiff as a result of the excess weight you’ve acquired. When your ligaments relax in preparation for labour, you can experience pain in your pelvis and hips. Try to maintain proper balance to relieve strain on your back. Sit up straight and in a chair that supports the back. Sleep on your side with a cushion between your legs at night. Wear stylish, low-heeled shoes with strong arch support. Using a hot pad to relieve back pain. Ask the doctor if paracetamol is safe for you to take.


  •  Bleeding. Light bleeding toward the end of your pregnancy could signal the start of labour. Spotting, on the other hand, could indicate a severe condition, such as placenta previa (when the placenta develops low and covers the cervix), placental abruption (when the placenta separates from the uterine wall), or preterm labour. As soon as you find any bleeding, call the doctor immediately.


  • Braxton-Hicks contractions. Mild contractions will begin, which are warm-ups to brace your uterus for the actual labour to come. Braxton-Hicks contractions aren’t as strong as actual labour contractions, but they do sound similar to labour and progress to it. The big distinction is that actual contractions become more and closer together as time goes by, as well as being more serious. Contact the doctor whether you’re red in the face and short of control following the contractions, even if they’re coming on a daily basis.


  •  Breast enlargement.   Your breasts would have expanded by up to 2 pounds by the conclusion of your birth. So that your back doesn’t hurt, make sure you’re wearing a comfortable bra. You may see a yellowish fluid dripping from your nipples when you get closer to your due date. This is known as colostrum, a fluid that will nourish your baby in the first few days after birth.

  •  Vivid dreams. In the third trimester, it’s normal to experience more intense hallucinations or nightmares. This will cause you to lose sleep. Changes in hormone levels induced by pregnancy are more likely to blame for your bizarre hallucinations.
  • Clumsiness. During the third trimester, you may feel clumsy or unbalanced. You could lose your balance. You’ve gained weight throughout your body, which is part of the cause. This makes it more difficult to maintain the body’s balance.
  • Discharge. During the third trimester, you may see further vaginal discharge. Contact the doctor if the flow is large enough to seep into your pantyliners. You may see a dense, clear, or slightly blood-tinged discharge when you get closer to your due date. This is the mucus plug, and it means your cervix is starting to dilate in preparation for labour. If you suddenly feel a rush of blood, it’s possible that your water has broken (although only about 8% of pregnant women have their water break before contractions begin). When your water splits, call your doctor as soon as possible.
  • Fatigue. You may have been energised during your second trimester, but now you’re tired. Carrying additional weight, getting up many times during the night to use the restroom, and coping with the fear of expecting a baby will all drain the energy. To offer yourself a boost, eat nutritious foods and exercise regularly. If you’re sleepy, consider taking a break or sitting down and relaxing for a few minutes. You can save all of your stamina for when your baby comes and you won’t be able to sleep.
  • Frequent urination. Your baby’s head could be pulling down on your bladder now that he or she is taller. Because of the increased demand, you’ll have to go to the toilet more often, perhaps multiple times a night. When you cough, sneeze, laugh, or exercise, you might notice that you’re leaking urine. Go to the toilet anytime you feel the need and urinate absolutely each time to ease the pain and avoid leakage. To reduce the number of late-night bathroom calls, avoid consuming fluids just before bedtime. Use a pantyliner to absorb any leaks that can arise. If you have some pressure or burning while urinating, tell the doctor. These symptoms may indicate a urinary tract infection.
  • Heartburn and constipation. They’re activated by an increase in progesterone levels, which relaxes those muscles, including those in your oesophagus that hold food and acids down in your stomach, as well as those that carry digested food into your intestines. To prevent heartburn, consume smaller, more regular meals during the day and eliminate items that are greasy, salty, or acidic (like citrus fruits). Increase your fibre consumption and consume plenty of water if you’re experiencing constipation. If you’re having trouble with heartburn or constipation, speak to the doctor about which drugs are appropriate to take for symptom relief.
  • Haemorrhoids. Varicose veins, or enlarged veins that develop around the buttocks, are what haemorrhoids are. During birth, these veins expand when more blood flows into them, and the weight of the baby puts more strain on the area. Sitting in a warm pool or sitz bath may help to ease the itching and pain. Ask with the doctor about using an over-the-counter hemorrhoid ointment or stool softener.
  • Leaky breasts. You may find a fluid called colostrum leaking from your nipples at the end of your pregnancy. Colostrum nourishes your baby through breastfeeding before you produce milk soon after birth.

  • Sciatica. In the third trimester, you’re most likely to experience nerve pressure that runs from your lower back to your buttocks and down your thigh. Sciatica may be triggered by hormonal fluctuations or by the baby’s rising body pressing against the sciatic nerve during pregnancy. Sciatica discomfort may be intermittent or persistent. Pain may be relieved with yoga, massage, or physical therapy, but it normally goes away after your baby is born.
  • Shortness of breath.Your uterus grows until it sits just under your rib cage as it extends, allowing little space for your lungs to develop. It could be more difficult to breathe as a result of the increased strain on your lungs. Shortness of breath may be alleviated by exercising. You should also use pillows to hold up the head and neck when sleeping.
  • Spider and varicose veins. Your blood flow has improved in order to provide more blood to your rising infant. Spider veins are tiny red veins that develop on the skin as a result of excessive blood flow. Spider veins may become more noticeable during the third trimester, but they should disappear after your baby is born. Your increasing baby’s pressure on your legs can cause some surface veins in your legs to swell and turn blue or purple. Varicose veins are what they’re called. Within a few months after giving birth, they should improve. While there is no way to eliminate varicose veins, you can slow their progression by doing the following:
    • Getting up and moving throughout the day
    • Wearing support hose
    • Propping up your legs whenever you have to sit for long periods.
  • Stretch marks. Stretch marks can appear on your breasts, buttocks, tummy, or thighs. Stretch marks are scars caused by the stretching of your skin during birth. They aren’t for everybody. They may be red, yellow, pink, or brown in colour if you see them.
  • Swelling. These days, your rings can seem tighter, and you may find that your ankles and face seem swollen. Excessive fluid retention causes mild swelling (oedema). Place your feet up on a stool or box if you sit for some amount of time to avoid swelling, and raise your feet when sleeping. If you notice unexpected swelling, get medical help right away because it may be a symptom of preeclampsia, a serious pregnancy complication.
  • Weight gain. During the third trimester, aim for a weight increase of 1/2 to 1 pound every week. You should have gained between 25 to 35 pounds at the conclusion of your birth (your doctor may have recommended that you gain more or less weight if you started out your pregnancy underweight or overweight). The placenta, amniotic fluid, elevated blood and fluid flow, and additional breast tissue all contribute to the extra pounds you’ve gained. Your doctor will do an ultrasound to monitor the baby’s development whether your baby seems to be too little or too large depending on the scale of your uterus.


Red Flag Symptoms

Any of these signs could indicate that your pregnancy is not going as planned. Do not put things off until the next prenatal appointment. If you have any of the above symptoms, contact the doctor right away:

  • Abdominal discomfort or cramps that are serious
  • Nausea or vomiting which is serious
  • Bleeding
  • Severe dizziness
  • Pain or a burning sensation during urination.
  • Gaining weight quickly (more than 6.5 pounds per month) or a lack of weight gain


Referenced on  10.4.2021

  1. American Congress of Obstetricians and Gynecologists: “Skin Conditions During Pregnancy."
  2. Department of Health and Human Services: “Varicose Veins and Spider Veins."
  3. Roberts, J.R., Hedges, J.R., eds., Clinical Procedures in Emergency Medicine, 5th edition, Philadelphia, Saunders Elsevier, 2009.
  4. Gabbe, S.G., Niebyl, J.R., Simpson, J.L., eds., Obstetrics: Normal and Problem Pregnancies, 5th edition, Philadelphia, Churchill Livingstone Elsevier, 2007.
  5. Bope, E.T., Rakel, R.E., Kellerman, R., eds., Conn’s Current Therapy 2010, 1st edition, Philadelphia, Saunders Elsevier, 2009.
  6. Ratcliffe, S.D., Baxley, E.G., Cline, M.K., eds., Family Medicine Obstetrics, Philadelphia, Mosby Elsevier, 2008.
  7. March of Dimes: “Weight Gain During Pregnancy."
  8. “Third Trimester: Weeks 29 to 40.”
  9. Stanford Children’s Health: “Third Trimester.”
  10. StatPearls: “Embryology: Lanugo.”
  11. Sleep Medicine: “Disturbed dreaming during the third trimester of pregnancy.”
  12. National Sleep Foundation: “How Pregnancy Can Affect Your Dreams.”
  13. University of Utah Health: “My Pregnancy Is Making Me Clumsy–Am I Normal?”
  14. American Academy of Dermatology: “Stretch Marks: Why They Appear and How to Get Rid of Them.”
  15. Cleveland Clinic: “How to Handle Sciatica During Your Pregnancy.”
  16. Mayo Clinic: “Bleeding during pregnancy.”

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