Things That Change in Your Body When Pregnant

Pregnancy changes a lot of things and affects your body in so many ways. There are changes which can be noticed emotionally, psychologically, socially, economically and physically. But we will consider in this article, only some of the physical changes that a pregnant woman may notice in the her body and body functions. It is important to note however, that although these changes can be noticed in just about every system in your body when pregnant, they can not be regarded as pathological (a disease) because they usually disappear after the pregnancy period is over when you must have successfully put to bed.

Changes That Occur in Your Body When Pregnant

Hormones are responsible for almost every physiological change that occur during pregnancy. Some of the hormones increases during pregnancy, whiles some decrease.

  • Progesterone increases and reaches a maximum of 250mg per day.
  • Estrogen levels increase up to a thousand fold due to placental production of the hormone in addition to the fetal adrenals.
  • Aldosterone is increased promoting water and sodium retention.
  • Plasma renin is 5 – 10 times more during pregnancy. This also accounts for the increase in angiotensinogen and angiotensin levels.
  • Human chorionic gonadotropin (hCG) levels increase and reach its peak levels in the first trimester.
  • Pituitary hormones like follicle stimulating hormone (FSH) and Luteinizing Hormone (LH) are suppressed during pregnancy.
  • Prolactin levels are high throughout pregnancy.

Changes in Your Weight


As the baby grows in your womb, your weight increases by about 25%, which is approximately 12.5kg added to your norm weight before the pregnancy. The main weight increase occurs in the second trimester of pregnancy and is usually around 0.5kg per week. Towards the end of the pregnancy however, the rate of weight gain begins to diminish and weight may fall after 40th week.

The reason for the weight increase during pregnancy is a combined result of fetal growth, enlargement of maternal organs, maternal storage of fats and proteins, and increase in maternal blood volume and interstitial fluid.

Changes in Your Reproductive System

Pregnancy causes your breasts to increase in size due to proliferation of the glands and ducts under the influence of high estrogen and progesterone levels. The secretion of colostrum (initial breast milk) may begin in the first trimester and continue through out the pregnancy.

The weight of the uterus will also increase from about 50g (when not pregnant) to about 1000g during pregnancy. In addition, your cervix softens due to increased vascularity and secrets more mucus called operculum that covers the opening of the cervix.

Most pregnant women may notice increased vaginal discharge during pregnancy vaginal and pelvic changes also occur. The walls of the vagina also becomes more muscular to allow stretching during child birth.

Changes in Food Metabolism

Pregnancy affects how you metabolise and utilise the food you consume especially carbohydrates, proteins and fats.

There will be a noticeable change in your blood glucose level. Your blood glucose levels remains high after eating a meal to facilitate transfer of glucose to the baby through the placenta. This explains why a pregnant woman could be at risk of a condition called gestational diabetes (high blood glucose level during pregnancy). The reason for the high glucose levels is because of the high demand of the fetus to obtain an easily convertible source of energy, aggravated by the need to store up energy for future demands such as lactation and growth of the pregnancy.

You will also notice an average of about 20% increase in dietary intake of protein during pregnancy. Half of the protein diets you consume metabolised for your body’s use and the remaining half for your baby and the placenta.

Fat metabolism also changes during pregnancy. Actually, fat is the major form of stored energy during pregnancy. When you are pregnant, most of it is stored in the form of depot fat in your abdominal wall, back, thigh and breasts.

Changes in Your Respiratory System

The physical changes in your respiratory system can begin early in pregnancy and are responsible for the improvement in gaseous exchange. Your respiratory rate will likely remain unchanged but your diaphragm will become more elevated to decrease the volume of your lungs at rest. This raises the volume of air going out of your lungs by up to 40% leading to an increase in the minute ventilation from 7.25litres to 10.5litred. Because of this, the concentration of carbondioxide in your blood gets reduced by around 8% compared to when you were not pregnant.

Changes in Your Cardiovascular System

Your heart pumps more blood when you’re pregnant. Cardiac output (the volume of blood pumped by the heart in one minute) increases dramatically from 4.5litres per minute to 6.0litres per minute. This increase is seen more in the first trimester and reaches its peak by the 24th week of pregnancy.

In addition, your heart rate increases from an average of 70 beats per minute to an average of 78 beats per minute by the 20th week, and up to a peak average of 85 beats per minute in late pregnancy. You may also notice an increase in your blood pressure in order to improve organ perfusion during pregnancy. Some women could end up with very high blood pressure during pregnancy which predispose them to a condition called pre-eclampsia.

Increased venous pressure is responsible for varicosities and swelling of the vulva and legs which are most visible during the day time due to upright posture, but less at night when you lay in bed.

Changes in Your Gastrointestinal System

Generally, the growth of fetus tends to increase your appetite and thirst.

Pregnant women tend to experience a lot of heart burns and acid reflux. This is due to the relaxation of smooth muscles caused by high progesterone levels during pregnancy. There is also a slight reduction in gastric emptying (movement of food from your stomach into your small intestine). This is what makes you feel nauseated and vomit during pregnancy.

Movement of food through your large intestine becomes slower during pregnancy and why pregnant women can have constipation.

Changes in Your Urinary System

When you are pregnant, there are changes that begin to occur in your pelvic organs. It is these changes in your pelvic anatomy that makes you go to pee very frequently especially in early pregnancy and late pregnancy.

Glomerular filtration rate (the rate at which your kidney filters certain substances during formation of urine) also increases during pregnancy, which accounts for glucosuria (high glucose in urine). High glucose seen in the urine during a urinalysis test is an indication of diabetes.



  • Kelvin P. Hanretty : “maternal physiology” Obstetrics and Gynaecology Illustrated (sixth edition).
  • Women’s Health – Body changes and Discomfort

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