Last pregnancy trimester

The Third Trimester | Johns Hopkins Medicine

What You Need to Know

• As you begin the third trimester, your health care provider or midwife may change the schedule of your prenatal visits from monthly to every two weeks.
• It’s a good idea to start taking childbirth classes in preparation for your baby’s birth, especially if this is your first pregnancy.
• By the end of the third trimester, the fetus is about 19 to 21 inches long and weighs, on average, 6 to 9 pounds.

Prenatal Visits During the Third Trimester

During your second and third trimester prenatal visits, your health care provider or midwife may check the following, depending on your current medical condition and the health of your fetus:

• Any current symptoms or discomforts

• Your weight

• Your blood pressure

• Urine test. This is to find albumin, a protein that may indicate pre-eclampsia or toxemia, and glucose, which may indicate hyperglycemia.

• Position, growth and development of your fetus

• Height of the fundus (top of the uterus)

• Fetal heartbeat

As you begin the third trimester, your health care provider or midwife will change the schedule of your prenatal visits from monthly to every two weeks. Your prenatal visits may be scheduled once every week in the last month. This schedule will depend on your medical condition, the growth and development of the fetus, and your health care provider or midwife’s preference.

Toward the later weeks of the pregnancy (starting at approximately the 38th week), a pelvic exam may be done to determine the dilation and effacement of the cervix. Your health care provider or midwife will also ask about any contractions and discuss labor and delivery procedures.

The Third Trimester: What to Expect

The third trimester marks the home stretch, as you prepare for the delivery of your baby. The fetus is continuing to grow in weight and size, and the body systems finish maturing. You may feel more uncomfortable now as you continue to gain weight and begin to have false labor contractions (called Braxton-Hicks contractions).

During the third trimester, it is a good idea to start taking childbirth classes in preparation for the big day. This is especially true in the case of first pregnancies.

Johns Hopkins Hospital Designated as Baby-Friendly

The Baby-Friendly Hospital Initiative, a global program launched by the World Health Organization and the United Nations Children’s Fund, has designated The Johns Hopkins Hospital as Baby-Friendly. This designation is given to hospitals and birthing centers that offer an optimal level of care for infant feeding and mother-baby bonding.

Learn more

The Third Trimester: Changes to Your Body

In the third trimester, some women become increasingly uncomfortable as their due date nears. As the fetus grows in size and crowds the abdominal cavity, some mothers-to-be have difficulty taking deep breaths or getting comfortable at night for sleep, while others are free from any discomfort as they anxiously await the arrival of their new son or daughter.

The following is a list of changes and symptoms that you may experience during the third trimester:

• Your fetus radiates body heat, causing you to feel hot from increased skin temperature.

• The increased urinary frequency returns due to increased pressure being placed on the bladder.

• Blood pressure may decrease as the fetus presses on the main vein that returns blood to the heart.

• Swelling of the ankles, hands and face may happen (called edema), as you continue to retain fluids.

• Hair may begin to grow on your arms, legs and face due to increased hormone stimulation of hair follicles. Hair may also feel coarser.

• Leg cramps may happen more often.

• Braxton-Hicks contractions (false labor) may begin to happen at irregular intervals in preparation for childbirth.

• Stretch marks may appear on the stomach, breast, thighs and buttocks.

• Colostrum (a fluid in the breasts that nourishes the baby until the breast milk becomes available) may begin to leak from your nipples.

• Dry, itchy skin may persist, particularly on the stomach, as the skin continues to grow and stretch.

• Your libido (sexual drive) may decrease.

• Skin pigmentation may become more apparent, especially dark patches of skin on the face.

• Constipation, heartburn and indigestion may continue.

• You will have increased white-colored vaginal discharge (leukorrhea), which may contain more mucus.

• Backaches may persist and increase in intensity.

• Hemorrhoids may persist and increase in severity.

• Varicose veins in the legs may persist and increase in severity.

The Third Trimester: Fetal Development 

During the third trimester, your fetus continues to grow in size and weight. The lungs are still maturing, and the fetus begins to position itself head down. By the end of the third trimester, the fetus is about 19 to 21 inches long and weighs, on average, 6 to 9 pounds. Fetal development during the third trimester includes:

• The fetus can see and hear.

• The brain continues to develop.

• The kidneys and lungs continue to mature.

• By the 36th week, the head may “engage” (drop into the pelvic area), a process called lightening.

• The bones of the skull remain soft to make it easier to pass through the birth canal.

• For many babies, the irises of the eyes are slate blue. The permanent eye color will not appear until several days or weeks after birth.

• The fetus can suck its thumb and has the ability to cry.

• By 38 to 40 weeks, the fetus’ lanugo (fine, soft hair on the body and limbs) has disappeared almost completely.

• By 38 to 40 weeks, the lungs have matured completely.

• The baby is covered in vernix caseosa (or simply called vernix), a creamy, protective coating on the skin.

• The head will usually turn downward during the last couple of weeks of pregnancy.

Third trimester | Pregnancy Birth and Baby

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Once you reach the third trimester of pregnancy, you’re well over half way there. As you look forward to the birth of your baby, there is plenty to plan for and decisions to make. You might find you’re slowing down, or you might be filled with energy to clean, tidy and organise as you prepare for your baby’s arrival. This urge to clean is known as the ‘nesting’ instinct.

What is the third trimester?

Pregnancy is divided into 3 blocks of 3 months each – the first, second and third trimesters. Reaching week 27 of your pregnancy means you’re now in the third and final trimester. While this trimester could end at week 40, in reality it ends whenever your baby is born.

A baby is considered to have been born full-term if it is born in weeks 37 to 42 of pregnancy. A baby born before week 37 is considered premature, and if your baby has not been born by week 42, labour may be induced.

What happens to your body?

As you get closer to the time your baby will be born, here are some things you’ll notice:

• Your skin and ligaments continue to stretch to accommodate your growing baby.
• You get tired easily, and sleeping becomes more difficult.
• You experience heartburn and/or breathlessness, as the baby grows in your abdomen.

While these are all part of a normal pregnancy, you can take steps to minimise discomfort. Speak with your doctor or midwife for suggestions, particularly if you are in pain.

You may also experience Braxton-Hicks contractions, which are a tightening of the muscles of the uterus. They last around 30 seconds, are irregular and not painful. They are not labour contractions, and not a sign that labour has begun.

If this is your first baby, you may notice around 36 weeks that your baby has moved further down into your pelvis. This is often referred to as 'the baby has engaged or dropped'. You will notice more room near your ribs and breathing will become easier, but this also adds more pressure on your bladder (meaning more trips to the toilet).

In the last few weeks of this trimester your body begins to prepare for the coming labour. The cervix begins to soften, and many women notice a ‘show’. The ‘show’ is the release of the mucous plug that sits within the cervical canal during pregnancy, and is an early sign that your labour will soon begin.

Your emotions

During this last stage of pregnancy, you may be worried or anxious about labour and the birth, or about how you will manage as a parent.

Difficulty getting comfortable in bed and frequent bathroom visits can mean poor sleep, which is known to trigger irritability and low mood in some people.

Although most pregnant women see the third trimester as an exciting time and feel positive about the next stage, one in 5 will experience antenatal anxiety or depression. Seek help early if this is how you (or your partner) are feeling.

What happens to the baby?

By week 31, your baby’s lungs are more mature, but are yet to produce surfactant, a substance that helps with breathing once they are born.

By week 36, your baby is about 47cm long and weighs approximately 2. 6kg. Your baby’s head may start to engage or sit lower into your pelvis at this time, getting ready for labour. Around one in 25 of all babies will be in the ‘breech position’, rather than the usual head-down position, at the start of labour. If this is your situation, your doctor or midwife will discuss with you what this means for your labour, what your options are and how your baby might be born.

By 40 weeks, your baby will be about 50cm, and weigh approximately 3.4kg. Developmentally, your baby is now ready to be born.

What to expect with your doctor or midwife?

Through the third trimester you will have frequent antenatal check-ups: about every 4 weeks until 36 weeks, then every 2 weeks after that.

If you haven’t already had them, the following may be offered:

• gestational diabetes check
• strep (streptococcal) B check
• whooping cough (pertussis) vaccination
• flu (influenza) vaccination

How to stay healthy

To give your baby a healthy start, it’s important to eat healthy foods throughout pregnancy. Ensure your diet is varied and includes a range of fresh fruit and vegetables as well as sources of protein, iron and calcium. Don’t forget to drink plenty of water too.

Weight gain is a normal part of pregnancy and most women can expect to gain between 11 and 16kg.

A pregnancy weight gain calculator can be a handy tool to track your weight gain through the third trimester.

Try to stay active throughout pregnancy - even in your third trimester. While it's important to stick with safe, gentle exercise as you get closer to your due date, recommendations state that pregnant women without complications are encouraged to participate in regular exercise as part of a healthy lifestyle.

Things to consider

As you enter the third trimester don’t forget to:

• pack a hospital bag
• book a hospital/birthing centre tour
• arrange a properly-fitted car seat (to bring your baby home)
• consider what you will need when you bring your baby home – what will you buy, can you borrow from family or friends?
• if you have other children (or pets), plan for their care while you are in hospital
• consider shopping ahead – especially for non-perishable staples (tinned foods, bathroom products, etc. )
• cook double portions through your third trimester, and load your freezer for when things get busy once the baby is born

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Last reviewed: May 2021

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Related pages

• First trimester
• Second trimester
• Pregnancy week-by-week

Need more information?

Third trimester: pregnancy week by week | Raising Children Network

Pregnant? In our pregnancy week by week guide, you can find out what to expect and follow your baby's development during the third trimester.

Read more on raisingchildren.net.au website