The third trimester marks the last third of pregnancy and begins around week 29.
For many, the third trimester is the most challenging trimester of pregnancy as a growing uterus places more demands on the body, and anxiety about the approaching delivery increases.
Here is how the body changes during the third trimester of pregnancy.
Most people are very visibly pregnant by the third trimester. As the weeks pass, the bump grows larger, forcing the organs to work harder and putting more pressure on the bladder, cervix, back, and legs.
Most doctors recommend that pregnant people gain
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Both too much and too little weight gain can increase the risk of some pregnancy complications, but dieting and food restrictions are unsafe during pregnancy.
Learn more about third trimester weight gain here.
According to one article, some typical third trimester changes include:
- Swelling: Most people experience some swelling late in pregnancy because of additional weight and fluid retention. Swelling may warn of a serious complication when it is uneven, very severe or painful, or when an area of the leg feels warm.
- Hemorrhoids: These painful veins around the rectum can itch and burn. They usually go away after pregnancy and get worse if a person is sedentary, constipated, or strains to pass stool.
- Varicose veins: Veins have a valve in them that prevents blood from flowing backward. But the additional weight gain of pregnancy can damage this valve and slow blood flow, causing spidery veins. The veins may be painful. Sometimes they go away after pregnancy, but they may last longer.
- Pelvic and groin pain: Dysfunction of the pubic symphysis ligament can cause shooting pains in the groin, rectum, or vagina. Some people also report round ligament pain, which causes intense, sharp pains in the hips or on either side of the abdomen.
- Bladder leakage: The urge to urinate becomes stronger later in pregnancy because of pressure on the bladder. Some people also notice bladder leakage due to changes in the pelvic floor muscles.
- Trouble sleeping: Anxiety about the pregnancy, aches and pains, restless legs, and trouble getting comfortable can make sleeping difficult. Some pregnant people also experience unusual dreams or heartburn at night.
- Reflux and heartburn: The growing uterus pushes up on the stomach. This can cause acid to travel back up the esophagus, causing intense heartburn. Eating smaller and more frequent meals may help.
- Leg pain: Some people experience intense calf cramps during pregnancy. The cramps usually last only a few minutes but can range from annoying to excruciating. Many people also experience restless leg syndrome and generalized leg achiness and heaviness.
- Breast pain: Growing breasts, hormonal changes, and similar shifts can cause breast pain and pressure.
- Shortness of breath: It is common to feel short of breath late in pregnancy, especially in the heat or after exercising. Chest pain and severe shortness of breath, however, may signal a more serious problem.
During prenatal appointments, a provider will monitor for:
- gestational diabetes
- high blood pressure
- problems with the fetus, such as decreased movement or abnormal growth
- swelling and protein in the urine, which might be a sign of preeclampsia
The American College of Obstetricians and Gynecologists (ACOG) indicate that exercise can help ease many pregnancy aches and pains, including swelling, varicose veins, restless legs, and more. Exercising during the day may help a person sleep better at night.
Regular exercise may also reduce the risk of certain pregnancy complications, such as gestational diabetes and high blood pressure.
It is safe to exercise during pregnancy. However, all pregnant people should discuss their exercise plans and goals with a healthcare provider. Some people may need to scale back the intensity or try different exercises. Some exercises that most people can safely do during pregnancy include:
- stretches, yoga, and Pilates
ACOG recommend that pregnant people eat about 450 extra calories per day during the third trimester.
Some nutritional strategies that can help keep the pregnant person and fetus healthy include:
- eating smaller, more frequent meals to feel fuller and prevent heartburn
- taking a daily prenatal vitamin that contains at least 400 micrograms (mcg) of folic acid
- eating a varied diet that includes fruits and vegetables, protein, sources of vitamin D, such as dairy, and sources of healthful fats and oils, such as nuts
- avoiding large fish, such as tuna and mackerel, which tend to contain higher levels of mercury
- avoiding undercooked or uncooked food, unpasteurized milk, and unpasteurized cheeses
- consuming sources of choline, which aids fetal brain development. Eggs and most meats are rich in choline
The CDC state that people having multiples should gain more weight than those with a single fetus. They recommend that people who had underweight at the start of their pregnancy aim to gain 50–62 lb, those who had moderate weight gain 37–54 lb, and those who had overweight should gain no more than 31–50 lb.
People who are having multiples usually experience pregnancy symptoms earlier on. Their symptoms might also be more intense. It is common for pregnant people with multiples to have more swelling, more severe hemorrhoids, and earlier shortness of breath.
ACOG state that people pregnant with multiples may undergo delivery slightly earlier in the pregnancy. In some cases, depending on the health of the pregnancy, a doctor may recommend a scheduled delivery via induction or cesarean delivery.
Not all providers are comfortable delivering multiples. Talk to a doctor or midwife about delivery options, and the risks and benefits of each type.
Expect to see an obstetrician or midwife more frequently during the third trimester.
Every provider is different, though most providers recommend a visit every 2 to 3 weeks after 28 weeks for uncomplicated, healthy pregnancies. At 36 weeks, most people see their provider weekly. People who go past 40 weeks or those with high risk pregnancies might see their provider a few times a week.
It is important to discuss all symptoms with a provider at each visit. The third trimester is a good time to discuss delivery plans, ask questions, and begin planning for postpartum care.
Late in pregnancy, the fetus should turn its head down. If this does not happen, a doctor may recommend attempting to turn the fetus or discuss the risks and benefits of breech vaginal delivery versus a planned cesarean section.
A person should contact a doctor or midwife if:
- they experience contractions
- they develop new unexplained aches and pains, such as intense stomach pain
- they have two high blood pressure readings
- they experience a persistent headache or changes in vision
- develop chest pain
- they bleed from the vagina
- they develop a fever, very itchy skin, or any signs of illness
More weight gain and a larger fetus can make the third trimester difficult. A healthful lifestyle and the right support from a compassionate care provider can make the last trimester of pregnancy less stressful and more manageable.
Anyone with concerns about their pregnancy should speak to a doctor.