8 ways your body changes during pregnancy

We take a closer look at all the strange changes your body goes through during pregnancy.


All these changes that occur during your pregnancy are essential adaptations to facilitate the needs that occur during pregnancy,” says obstetrician and gynaecologist, Dr Rafik Bala Mia.

Cardiovascular system

During pregnancy, your blood plasma will increase in volume by up to 50%. “A slight increase in the heart rate and a decrease in blood pressure may also be experienced during pregnancy,” explains Dr Mia.

“The position you sleep in can also influence your blood pressure,” explains Tamzin Ingram, a midwife from Johannesburg. “When a mom lies on her back, her blood pressure will drop and she may feel nauseous and generally unwell. Your baby won’t be affected if you change your position when this happens.”

“The increase in blood volume in a pregnant woman’s body is important because it gives the mom reserve blood for the birth process. A pregnant woman also needs extra blood to feed her growing reproductive organs,” says Tamzin.

During pregnancy, there are more clotting agents in the blood, which places a mom at a higher risk for deep vein thrombosis. “This is why it is important for pregnant women to get up and move around regularly if they’re flying or taking long road trips,” explains Tamzin.

ALSO SEE: Traveling while pregnant


“During pregnancy, your uterus becomes enlarged and it usually twists to the right-hand side of your body,” explains Tamzin. Your uterus will grow from 50g to 1kg during your pregnancy. There will be an increase in blood to your cervix, causing it to change colour and become a blue-purple colour. You may experience spotting after intercourse. It’s important to note that any spotting or bleeding during pregnancy should be reported to your caregiver immediately.



The pH levels in your vagina change once you become pregnant. “This is one reason why moms are more prone to thrush during pregnancy,” explains Tamzin.

ALSO SEE: What to expect (for your vagina) when you’re expecting

The respiratory system

“The main change that takes place in your respiratory system during pregnancy is the circumference of your chest cage that increases. There’s also an upward displacement of the diaphragm because of your enlarging uterus,” explains Dr Mia.

Other changes include an increase in blood flow. The use of oxygen is also increased when you’re pregnant. Because of the enlarging uterus, slight pressure and shortness of breath during this period is normal. “If this becomes disturbing, seek professional advice.”
Tamzin adds that although you will still breathe at the same rate, pregnant women will take deeper breaths.

ALSO SEE: 5 ways to reduce shortness of breath during the third trimester

The gastrointestinal system

As your pregnancy progresses, your uterus enlarges. Your uterus rises up and out of your pelvic cavity, displacing your stomach, intestines and other adjacent organs to the back and sides of your abdomen. During the middle of your pregnancy, this pressure can slow your digestion, which can lead to constipation and flatulence. “The hormone progesterone relaxes the intestines which results in slower transit times and constipation,” explains Tamzin.

ALSO SEE: Dealing with constipation and 4 other pregnancy niggles sorted

What’s more is that the pressure from your uterus on the veins returning from the lower extremities can lead to haemorrhoids. “Haemorrhoids are also a result of progesterone, which relaxes the vessel walls, as well as pressure from the growing baby,” explains Tamzin.

“Heartburn is caused by the relaxing effect of progesterone as well.” The valve, which is found between the stomach and the oesophagus, becomes soft and relaxed due to the pregnancy hormones and allows the stomach acid to pass into the pipe, which leads to heartburn.

The renal system

The renal system involves the kidneys and the bladder. The blood flow, as well as the filtration rate of the kidneys, increases during pregnancy. “The filtration system is open to larger molecules passing through when a woman is pregnant. This is why blood may be detected in the urine when a pregnant mom has her urine checked at her regular check-ups. It’s important to investigate the problem just to make sure it’s normal,” explains Tamzin. The production of the hormone rennin in the kidneys increases during pregnancy, which contributes to the retention of fluids in your body.

ALSO SEE: 3 things doctors look for in your urine during pregnancy

Tamzin mentions that the enlarged uterus presses on the bladder, which causes a decreased bladder capacity, which is why you need to go to the loo more. The relaxation of the bladder is a result of the progesterone, which relaxes the ureters (the tubes that take the urine from your kidneys to your bladder). This can lead to urinary stasis, which may increase your risk of getting a urinary tract infection

The blood system

The haematological, or blood, system plays a role in the cardiovascular system during pregnancy, as well as after delivery, to prevent excessive blood loss. “The total blood volume is increased and may cause dilutional anaemia during pregnancy, so don’t be alarmed if there is a small decrease in your blood iron level,” says Dr Mia.

The clotting ability of your blood increases when you’re pregnant.  Inform your doctor if you previously had, or suffer from varicose veins or had blood clots in your legs or lungs. The protein level is decreased during pregnancy, which contributes to the swelling in your legs. Excessive swelling should be attended to in order to exclude hypertension in pregnancy.

ALSO SEE: High blood pressure during pregnancy – what you need to know

The endocrine (hormone) system

There is a slight enlargement of the thyroid during pregnancy, but this shouldn’t affect your pregnancy. Notify your doctor if you notice a lump or growth in your thyroid.

There’s an increase in prolactin levels during pregnancy, which aids breast changes to allow for breastfeeding once the baby is born. Regular self-breast examination is important to identify abnormal breast lumps.

The cortisol and rennin levels increase during pregnancy, increasing your blood volume.

Your glucose levels also increase during pregnancy, so it’s important to tell your doctor if you have diabetes.

Your calcium levels decrease when you’re pregnant which may result in cramps, or mild reversible osteoporosis of pregnancy. It can also decrease your breast milk supply.

Your basal metabolic rate is increased during pregnancy. (This is why people say you are eating for two). Your increased metabolism is also the reason you get hot and tired very quickly when you are pregnant.

Uncomfortable changes in your body

First trimester

  • Nausea and vomiting
  • Breast tenderness
  • Cramping in the lower abdomen and in the legs

These pregnancy discomforts are mainly due to pregnancy hormones. These conditions usually settle and don’t always require treatment or hospitalisation, unless they’re excessive. The nausea is usually relieved by eating smaller meals instead of your three course meals three times a day.

ALSO SEE: What to eat to treat your pregnancy niggles

Second trimester

The second trimester is the best period of your pregnancy. You can feel baby’s movements now, people can see you’re pregnant, and it may be time to get a new wardrobe. You may experience some pressure symptoms, tendon pain, cramps or swelling of the feet if you stand or sit for long periods. You can relieve the swelling by regularly walking around and elevating your legs with pillows when you’re at home.

ALSO SEE: 7 genius hacks to turn your everyday clothes into maternity wear

Third trimester

The ‘honeymoon’ period is over now. Pregnant women can expect to feel anxious or nervous, and will experience more effects resulting from the pressure of the growing baby during their third trimester. Early in your third trimester, you may experience pressure effects from your rib cage and you may be short of breath. You may feel pressure and sometimes a little pain when baby moves around. The pressure effects on your bladder will start to affect you later on in the third trimester as a result of relaxation hormones. Relaxation exercises and a warm soak in the bath tub for about 15 minutes will do wonders for you.


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