Physical changes

Pregnancy is a time when your body undergoes dramatic changes. Many of these changes take place without you even being aware of them, while others can cause a certain amount of discomfort.

Heart and blood vessels

During pregnancy, your heart rate can increase by up to 10 beats per minute, and the volume of your blood by 40% to 45%, to meet the needs of the fetus. Your heart actually shifts slightly within your rib cage as your uterus expands.

In some women, the increased volume of blood and the pressure created by the expanding uterus can cause varicose veins. These are veins that become enlarged, hampering blood circulation. Varicose veins occur primarily on the legs, anus, vulva, and vagina.

Here are a few ways you can help prevent varicose veins in the legs:

  • Elevate your legs
  • Sleep on your left side
  • Be physically active
  • Avoid prolonged periods of sitting or standing
  • Wear compression stockings


Many women are more aware of their breathing when they’re pregnant, and may find their breathing more laboured, even when resting.


Pregnancy hormones stimulate the skin and scalp, causing a noticeable effect in some women. Changes in your skin shouldn’t be cause for concern, as most will diminish or disappear altogether in the months following the birth.

Most pregnant women experience hyperpigmentation (darkening of the skin). This hyperpigmentation tends to be localized, usually appearing as a thin dark line between the belly button and the pubis. It can also occur as a darkening of the areola around the nipples or on the perineum, anus, neck, armpits, or the skin around the belly button.

The pregnancy mask some women get is also a result of hyperpigmentation. It is characterized by the appearance of brown patches on the face.

Hyperpigmentation and pregnancy mask clear up after the birth of the baby and generally disappear altogether within a year.

Hormonal stimulation of the skin can also result in the appearance of acrochordons (skin tags)—tiny benign skin growths that are most common in skin folds such as around the neck and armpits.

Some women may develop angiomas between the second and fifth months of pregnancy. Angiomas are small blood vessels that form little red patches on the skin. Most angiomas will disappear on their own within three months of giving birth.

In some cases, women may develop acne, which will disappear after the birth of the baby.

Stretch marks can also develop during pregnancy. They usually appear in the second half of pregnancy, mainly on the tummy, breasts, and thighs, but can also occur in the armpits or on the lower back, buttocks, and arms. Stretch marks are initially a pinkish or purple colour, and gradually become less apparent over time.

While there is no proven method for effectively preventing or treating stretch marks, application of a moisturizing cream with a massaging motion may help somewhat to reduce them, although the ingredients of the cream themselves appear to have little effect.


Head and body hair growth may change with pregnancy. Some women may experience increased hair growth on their bodies and have a thicker, fuller head of hair. After the birth, it is not uncommon to experience more hair loss than usual.

Bladder and kidneys

At the beginning of pregnancy, bladder function changes, which can trigger the need to urinate more urgently or more often. These sensations can also appear later in pregnancy when the uterus expands and the baby’s head puts pressure on the bladder.

During pregnancy the kidneys increase in volume. You will probably have to urinate more frequently at night. During the day, your body tends to accumulate water in your tissues, but when you go to bed these water reserves are sent to your kidneys and you feel the need to urinate—again!


Your breasts may become more sensitive and increase in size. The blue veins that crisscross their surface may become more visible. Your nipples and areolas prepare for breast-feeding by growing slightly and may also become darker. Little bumps form on the areolas: these are glands that produce oil that will help keep your skin moisturized and protected during breast-feeding.

Beginning at 16 weeks, the breasts start producing colostrum, the first food your baby will ingest after he is born. Some women may leak colostrum during pregnancy. This is normal.


Before pregnancy, your uterus is the size of a small pear. As your pregnancy advances, the uterus expands to meet the needs of the fetus, and changes shape and position in your abdomen.

Stomach and intestines

Digestion often slows down during pregnancy due to hormonal changes. This can cause constipation or acid reflux in the esophagus ou de la constipation.


The increasing weight of the uterus causes your posture to change and moves your centre of gravity further forward. That’s why the gait of some pregnant women may be somewhat different than usual.

Growth of the fetus in the uterus

Growth of the fetus in the uterus

Weight gain

All pregnant women gain weight: it’s normal and even desirable. Provided you eat a healthy diet, eat as much as you need to satisfy your hunger, and are physically active, you should gain the weight you and your baby need.

Weight gain can vary greatly from one woman to the next.It also depends on your weight before the pregnancy.

  • Women with a healthy weight before pregnancy can expect to gain between 11.5 and 16 kg, or 25 to 35 pounds.
  • Women carrying more than one baby (e.g., twins, triplets) will gain more weight.
  • Women who are overweight or underweight before pregnancy can ask their health professional or a nutritionist for advice on how to get the most from their diet.

At the beginning of pregnancy, weight gain varies from one woman to the next. Some women gain weight; others lose weight. Women who experience nausea may feel less or more hungry than usual (see Nausea and vomiting). Don’t be concerned about how much weight you gain in the early days of your pregnancy. Weight gain generally adjusts as the pregnancy progresses.

During pregnancy, you will gain weight gradually, at your own pace. Post-delivery weight loss is gradual and differs from one woman—and one pregnancy—to another.

Distribution of weight gain at 40 weeks pregnancy for a woman who has gained 12.5 kg (27½ lb.)

Total weight gain: 12.5 kg (27½ lb.). Maternal fat reserves: 3,345 g (71/4 lb) 27%. Uterus: 970 g (2 lb.) 6%. Amniotic fluid:
800 g (1¾ lb.) (6%). Extravascular fluids:
1,480 g (3¼ lb.) (12%). Breasts:
405 g (1 lb.) (3%). Placenta:
650 g (1½ lb.) (5%). Baby:
3,400 g (7½ lb.) (27%). Blood:
1,450 g (3¼ lb.) (12%).

Esophagus: Muscular tube that carries food from the mouth to the stomach.