Pregnancy: Physical changes and common discomforts

Pregnancy affects a woman’s entire body. The cardiovascular, digestive, respiratory, nervous, reproductive, and urinary systems are all impacted. It’s therefore normal to feel various aches and pains over the next few months.

Here are the main physical changes you’ll notice during your pregnancy and the most common discomforts that can develop.

Physical changes: First trimester

• You stop menstruating.
• Your uterus  starts expanding, but you’ll only notice a baby bump around the fourth or fifth month of pregnancy. Two months in, your uterus starts to grow 4 cm per month. At 12 weeks, it’s roughly the size of a grapefruit.
• Your breasts start to swell. They become heavier, firmer, and more sensitive. They may even be slightly painful. Your nipples and areolas also begin to grow larger and firmer.
• To meet your baby’s needs, your body must increase blood flow to the uterus. Your heart rate therefore rises six weeks into your pregnancy and remains high until delivery.
• The release of hormones lowers your blood pressure and slows down your digestive system. You may also produce more saliva, sometimes excessively.
• You feel out of breath. This is normal, as oxygen demand increases 15 to 20 percent during pregnancy. Your respiratory rate hasn’t increased. Rather, each breath pulls more oxygen into your lungs.
• You start to put on a bit of weight. However, some women may lose weight during this period due to nausea and vomiting.

Physical changes: Second trimester

• Your belly becomes rounder and you may notice stretch marks.
• Your uterus  continues to expand (4 cm in height per month). By the sixth month of pregnancy, it’s about 24 cm high.
• Your centre of gravity shifts as your pelvis prepares for childbirth. This change may cause an occasional loss of balance.
• You notice that certain areas of your body, like your nipples and scars, are darker. A brownish vertical line, known as the linea nigra, may appear between your pelvic region and navel. Irregular spots may also develop on your face. These will go away after the baby is born.
• Varicose veinsmay appear on your legs, and the veins in your breasts may become more visible.
• Your breasts grow, and colostrum may leak from your nipples.
• You gain weight (5–7 kg on average).
• Your teeth and gums are more sensitive and may bleed more easily.
• Your moods are likely more stable.
• You feel your baby’s first active movements (between weeks 18 and 20). If you’ve been pregnant before, you may feel them earlier (around week 16).

Physical changes: Third trimester

• At 7 months, the height of your uterus is about 28 cm. At 8 months, it reaches 30 cm, and then 33 cm at 9 months.
• Throughout the third trimester, you continue to gain weight, putting on about 4 kg (9 lb.).
• You may develop stretch marks on your stomach, thighs, and breasts. As your skin stretches, it can feel itchy.
• Colostrum, the fluid produced before the arrival of breast milk, may leak from your breasts.
• Your blood volume increases, which can result in anemia, a health problem characterized by low iron levels and fatigue.
• You are more flexible because your ligaments are softening and the joints in your pelvis are loosening.
• When you lie on your back, the weight of your uterus may block certain blood vessels, which can make you feel dizzy.

Common discomforts

Below is a list of the most common discomforts experienced during pregnancy. To learn more about a specific ailment, click on its name and consult the fact sheet.

• Heartburn
• Nasal congestion and nosebleeds
• Constipation and hemorrhoids
• Braxton Hicks contractions
• Leg cramps
• Groin pain
• Swelling of the legs and feet
• Pain and numbness in the hands
• Frequent urge to urinate
• Fatigue
• Mood swings
• High blood pressure
• Insomnia or light sleep
• Back pain
• Headaches
• Nausea and vomiting
• Vaginal discharge
• Shortness of breath
• Varicose veins in the legs
• Stretch marks

If you’re concerned about any of your symptoms, write them down and discuss them with your health care provider during your next appointment. Don’t hesitate to contact them between appointments or call Info-Santé (811) if your symptoms are worrisome. Some over-the-counter medications can relieve certain discomforts, but it’s important to talk to a doctor or pharmacist before taking any.

Things to keep in mind

• Certain physical changes develop in the early months of pregnancy.
• These changes affect the woman’s entire body.
• If you’re concerned about any of your symptoms, discuss them with the health care professional monitoring your pregnancy.

Scientific review: Roxanne Piché, nursing adviser, Maternal Fetal Medicine Clinic, CHU Sainte-Justine Research and copywriting: The Naître et grandir team Updated: November 2019