Third Trimester

What Mom Can Expect

This is the final trimester, and you and your baby are preparing for labor and delivery.  It’s a great time to start thinking about names and to pack a bag for your trip to the hospital.  Don’t worry if your baby decides to make his/her debut before or after the expected due date. Due dates are only an estimate since it’s virtually impossible to predict the exact date.

Prenatal Vitamins

In the last months of pregnancy, your baby’s brain is developing rapidly.1,2  It is especially important for you to consume DHA  (docosahexaenoic acid) for both you and your baby during the third trimester and the first few years of your baby’s life.  Extra iron is essential for the development of red blood cells which support your baby’s extra growth rate.  If you notice an increase in headaches, fatigue, paleness, or irritability, you may want to consult your doctor on a prenatal vitamin with extra iron.

Third Trimester

In the last three months of your pregnancy, the fetus experiences rapid growth in size and weight.  You will notice the baby is changing positions and becoming more active.  During this time, the fetus’ lungs and brain also continue to mature.

  • As your baby grows larger, the skin over your abdomen is tightly stretched and your navel may bulge outward
  • By weeks 24 to 25, the fetus can survive outside the uterus
  • The baby will likely turn to a head-down position at approximately 32 weeks in preparation for birth
  • Vernix caseosa, a greasy substance, appears on the baby’s skin to ease the passage of the baby during birth 
  • It’s normal late in pregnancy to experience maternal fatigue, swelling in the feet and legs, lower back pain, frequent urination and heartburn  

New Developments

As you enter your third trimester, you will notice that some of your earlier pregnancy symptoms have diminished and new ones have appeared.

  • Back — As your abdomen grows larger, your center of gravity changes and this can cause you to lean forward more than you normally do.  The extra strain on your lower back muscles can cause you to experience aches and pains you have not had before.If you have a sharp pain that runs from your lower back down your leg, this could be sciatica, which is an irritation to the tissue around your sciatic nerve or compression of the sciatic nerve.3 You will need to consult with your doctor or healthcare provider for instruction on how to properly treat this condition.
     
  • Breasts — You may experience a slight pale yellow discharge from your nipples which is called “colostrum.”  Colostrum consists of water which is fortified with proteins, minerals and antibodies. If you choose to breastfeed, colostrum will feed your baby until your milk comes in.3
     
  • Uterus — Your uterus continues to grow and by week 36, it may reach the base of your rib cage. Depending on your size, your uterus could continue to move upward into your diaphragm. You also may experience Braxton-Hicks contractions in your third trimester. As your uterus gets stronger and is preparing for labor, the muscles start to tighten for short periods causing the contractions.4  You’ll feel your uterus harden for about a minute and then return to normal.  This is common during the last month of pregnancy. 

Normal physical symptoms you may experience during your third trimester3,5:

  • Breathing is easier as labor approaches and the baby drops
  • Urination is more frequent after baby drops
  • Aches in lower abdomen may increase
  • Bleeding gums
  • Bloating, gas, indigestion and heartburn
  • Constipation
  • Cramping legs
  • Fetal activity is more frequent and stronger
  • Headaches, faintness, dizziness
  • Hemorrhoids
  • Protruding navel
  • Shortness of breath
  • Swelling of feet and ankles
  • Vaginal discharge
  • Varicose veins

How Your Baby is Growing

Your baby will be active and turn freely in the beginning of the third trimester.  Because of the substantial gain in body size and weight, he/she will become too large for somersaults near the end of the third trimester. As your due date draws near, your doctor may ask you to keep a record of the baby’s movements, such as counting and recording the number of kicks during a certain time of the day, just to make sure the baby remains active.  You may notice a rhythm to the baby’s movements, or you may feel that the baby moves more after you’ve eaten or late in the evening after going to bed.


  1. Carlson SE, Ford AJ, Werkman SH, Peeples JM, Koo WW. Visual acuity and fatty acid status of term infants fed human milk and formulas with and without docosahexaenoate and arachidonate from egg yolk lecithin. Pediatr Res. 1996 May; 39(5)882-B
  2. Dobbing J, Sands J. Quantitative growth and development of human brain. J Nutr. 1973 Sep;103(9): 1327-38
  3. Taber’s Cyclopedic Medical Dictionary. 20th ed. In: Venes D, editor. Philadelphia: F.A. Davis Company; c2005
  4. Mayo Clinic available from:http://www.mayoclinic.com/health/pregnancy/PR00018.
  5. Mayo Clinic Pregnancy symptoms: what to expect during the third trimester; 2011 Jun 18 . Available from: http://www.mayoclinic.com/health/pregnancy/PR00009.