Pregnancy: Physical changes and common discomforts

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 expands. This change will be noticeable in the second trimester, between the fourth and fifth months of pregnancy. If this is not your first pregnancy, however, you may start showing in your third month. 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 can even be a little painful. Your nipples become firmer and darker. The areolas also become darker. Glands may become visible on the areolas. These glands produce an oil that helps keep the skin moisturized and protected during breastfeeding.
• The release of hormones lowers your blood pressure and slows down your digestive system. You may produce more saliva, sometimes excessively.
• You feel out of breath. This is perfectly normal! Your 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.
• Your heart rate may increase slightly starting in the sixth week, as some of your blood flow is directed toward the embryo to meet its needs. Your heart rate will remain higher until the end of your pregnancy.

Physical changes: Second trimester

• Your belly gets rounder. Stretch marks may appear on your stomach.
• Your uterus continues to expand (4 cm in height per month). By the sixth month of pregnancy, it’s about 24 cm high.
• Your pelvis adjusts to prepare for the baby’s passage. This shifts your centre of gravity. This change may cause an occasional loss of balance.
• Certain areas of your body will darken, like your nipples and scars, if this hasn’t already happened during the first trimester. A brownish vertical line, known as the linea nigra, may appear between your pelvic region and navel. It will disappear several months after childbirth. Irregular spots may also develop on your face. This is known as melasma or the “mask of pregnancy.” It will fade or disappear after childbirth, as pregnancy hormones subside.
• Your heart rate increases by about 10 to 15 beats per minute between the 14th and 20th weeks of pregnancy, because some of your blood flow is directed toward the fetus to meet its needs. Your heart rate will remain higher until the end of your pregnancy.
• Varicose veins may appear on your legs, and you may notice bluish veins on your breasts. This is caused by an increase in blood volume, which causes your veins to dilate.
• Your breasts may grow, and a fluid called colostrum may leak from your nipples.
• You gradually gain weight. During the second trimester, you may gain between 225 and 500 g (0.5 to 1 lb) per week. Weight gain can vary, however, from one woman to another and from one pregnancy to another.
• Your teeth and gums are more sensitive and may bleed more easily.
• Your moods are likely more stable.
• Your complexion may become more radiant due to hormonal changes. Your hair may also become shinier and your nails may become stronger.
• You feel the first movements of your fetus (between the 18th and 20th week). If you’ve been pregnant before, you may feel movement earlier (around week 16).

Physical changes: Third trimester

• The height of your uterus (in centimetres) corresponds roughly to the number of weeks pregnant you are, give or take 2 cm. Toward the end of pregnancy, the height of the uterus stops increasing as the fetus descends into the pelvis.
• You continue to gain weight. During the third trimester, you may gain between 225 and 500 g (0.5 to 1 lb) per week. Weight gain can vary, however, from one woman to another and from one pregnancy to another.
• Your skin stretches, which may cause stretch marks to appear on your stomach, thighs, or breasts. As your skin stretches, it can feel itchy.
• Some colostrum may leak from your breasts.
• Your blood volume increases. This can lead to anemia, a health condition caused by iron deficiency. Anemia can cause fatigue.
• You become more flexible because your ligaments are softening and the joints in your pelvis are loosening up.
• You may feel dizzy. This is caused by the weight of your uterus, which blocks certain blood vessels when you are lying on your back.

What are some common pregnancy discomforts?

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

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

• Back pain
• Braxton Hicks contractions
• Constipation and hemorrhoids
• Fatigue
• Frequent urge to urinate
• Groin pain
• Headaches
• Heartburn and acid reflux
• High blood pressure
• Insomnia or light sleep
• Leg cramps
• Mood swings
• Nasal congestion and nosebleeds
• Nausea and vomiting
• Numbness and pain in the hands (carpal tunnel syndrome)
• Pregnancy gingivitis
• Rashes
• Reflux
• Shortness of breath
• Stretch marks
• Swelling of the legs and feet
• Vaginal candidiasis (yeast infection)
• Vaginal discharge
• Varicose veins in the legs
• Vertigo and dizziness

Some over-the-counter medications can relieve certain third-trimester discomforts, but be sure to speak to your prenatal care provider or pharmacist before taking any.

If you’re concerned about any symptoms, make a note of them and discuss them with your prenatal care provider. Feel free to contact them between appointments. You can also call Info-Santé 811 if you have any concerns.

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 your prenatal care provider.

Scientific review: Paméla Farman, M.Sc., nurse clinician and lecturer at the Université Laval faculty of nursing Research and copywriting:The Naître et grandir team Updated: May 2026

Photo: GettyImages/SanyaSM