Renal and lower reproductive tract changes

Genitourinary Changes in Pregnancy

Progesterone causes many changes to the genitournary system. A pregnant woman may experience an increase in the size of the kidneys and ureter due to the increase blood volume and vasculature. Later in pregnancy, the woman might develop physiological hydronephrosis and hydroureter, which are normal. Progesterone causes vasodilatation and increased blood flow to the kidneys, and as a result glomeruler filtration rate (GFR) commonly increases by 50%, returning to normal around 20 weeks postpartum. The increased GFR increases the excretion of protein, albumin, and glucose. The increased GFR leads to increased urinary output, which the woman may experience as increased urinary frequency. Progesterone also causes decreased motility of the ureters, which can lead to stasis of the urine and hence an increased risk of urinary tract infection.

Pregnancy alters the vaginal microboita with a reduction in species/genus diversity. Physiological hydronephrosis may appear from six weeks.


How to exercise safely?

[Pregnancy swimming]

Swimming whilst pregnant is an effective, safe form of exercise.

A few tips can help you stay safe when exercising.


  • begin by warming up for 5 minutes and stretching for 5 minutes
  • finish with 5 to 10 minutes of gradually slower exercise that ends with gentle stretching.

Here are some useful tips:

  • Wear loose-fitting, comfortable clothes, and a good support bra.
  • Choose supportive shoes designed specifically for the exercise you have chosen, to help prevent injury.
  • Exercise on a flat, level surface to avoid injury.
  • Eat small, frequent meals throughout the day, and don’t exercise for at least 1 hour after eating.
  • Drink plenty of water before, during and after exercise, to keep hydrated.
  • Get up slowly and gradually to prevent dizziness.

Remember that:

  • The body needs more oxygen and energy during pregnancy.
  • The hormone relaxin, produced during pregnancy, causes the ligaments that support the joints to stretch, increasing the risk of injury.
  • The mother’s changing weight alters the center of gravity, putting extra strain on the joints and muscles in the lower back and the pelvis and increasing the chance of losing balance.

Other infections during pregnancy

Pregnancy causes many changes in the body, making people more susceptible to complications from many infections.

For example, hormone-related skin changes during pregnancy can cause conditions such as eczema or severely dry skin. If the skin cracks open and bleeds, a serious skin infection, such as cellulitis, can develop. A rare skin disorder called Sweet’s syndrome is also more common during pregnancy than at other times.

Some other infections that may be more serious during pregnancy include:

  • the flu
  • hepatitis E, which is a typically mild viral form of hepatitis
  • herpes, including herpes simplex virus (HSV) and varicella zoster virus (VZV)
  • Listeria, which can cause food poisoning
  • measles
  • HIV

The increased risk of these infections during pregnancy is not well understood but may be due to hormone and other changes that alter the number of blood cells in the body. For example, late in pregnancy, T cells that help fight infection decrease in number.

Pregnancy also causes increased blood circulation and demands on the heart. These demands can also worsen complications. For example, if a pregnant person develops pneumonia from the flu, they may have more difficulty breathing because of the increased demands the fetus places on the heart and lungs.

Some medications that can effectively treat common infections may be less safe during pregnancy. So it is essential that pregnant people who have an infection talk to their doctor or midwife to weigh up the benefits and risks of various treatment options.


Blood volume and hemoglobin concentration

Maternal Blood Volume

During pregnancy the plasma volume increases by 40-50% and the red blood cell volume increases only by 20–30%. These changes occur mostly in the second trimester and prior to 32 weeks gestation. Due to dilution, the net result is a decrease in hematocrit or hemoglobin, which are measures of red blood cell concentration. Erytheopeotien, which stimulates red blood cell production, increases throughout pregnancy and reaches approximately 150 percent of their pregnancy levels at term. The slight drop in hematocrit or hemoglobin is most pronounced at the end of the second trimester and slowly improves when reaching term.

Platelet and white cell count

The effect of pregnancy on platelet count is unclear, with some studies demonstrating a mild decline in platelet count and other studies that show no effect. The white blood cell count increases with occasional appearance of myelocytes or metamyelocytes in the blood. During labor, there is a rise in leukocyte count.


A pregnant woman will also become hypercoaguable, leading to increased risk for developing blood clots and embolisms, such as deep vein thrombosis and pulmonary embolism. Women are 4-5 times more likely to develop a clot during pregnancy and in the postpartum period than when they are not pregnant. Hypercoagulability in pregnancy likely evolved to protect women from hemorrhage at the time of miscarriage or childbirth. In third world countries, the leading cause of maternal death is still hemorrhage. In the United States 2011-2013, hemorrhage made up of 11.4% and pulmonary embolisms made up of 9.2% of all pregnancy-related deaths.

The increased risk of clots can be attributed to several things. Plasma levels of pro-coagulantion factors increased markedly in pregnancy. Both the production of prostacyclin (an inhibitor of platelet aggregation) and thromboxane (an inducer of platelet aggregation and a vasoconstrictor) are increased, but overall there is an increase in platelet reactivity which can lead to a predisposition to clots. There is also increased blood stasis due to the compression of the vena cava by the enlargening uterus. Many factors have been shown to increase the risk of clots in pregnancy, including baseline thrombophillia, cesarean section, preeclampsia, etc. Clots usually develop in the left leg or the left iliac/ femoral venous system. Recently, there have been several case reports of May-Thurner Syndrome in pregnancy, where the right common iliac artery compresses the below left common iliac vein.


Edema, or swelling, of the feet is common during pregnancy, partly because the enlarging uterus compresses veins and lymphatic drainage from the legs.

Cardiovascular Changes

The heart adapts to the increased cardiac demand that occurs during pregnancy in many ways.

  • Cardiac output (Lit./Min.): 6.26
  • Stoke Volume (Ml.): 75
  • Heart Rate (Per min.): 85
  • Blood Pressure: Unaffected

Cardiac output increases throughout early pregnancy, and peaks in the third trimester, usually to 30-50% above baseline. Estrogen mediates this rise in cardiac output by increasing the pre-load and stroke volume, mainly via a higher overall blood volume (which increases by 40–50%). The heart rate increases, but generally not above 100 beats/ minute. Total systematic vascular resistance decreases by 20% secondary to the vasodilatory effect of progesterone. Overall, the systolic and diastolic blood pressure drops 10–15 mm Hg in the first trimester and then returns to baseline in the second half of pregnancy. All of these cardiovascular adaptations can lead to common complaints, such as palpitations, decreased exercise tolerance, and dizziness.

Uterine Compression of IVC and Pelvic Veins. Displacement of PMI by Uterus

Uterine enlargement beyond 20 weeks’ size can compress the inferior vena cava, which can markedly decrease the return of blood into the heart or preload. As a result, healthy pregnancy patients in a supine position or prolonged standing can experience symptoms of hypotension.

Which exercises during pregnancy are beneficial?

Before you begin exercising, remember it is important to talk to your health care provider. If you typically get little or no activity, walking is a great exercise to start with. Walking is usually safe for everyone, it is easy on your body and joints, and it doesn’t require extra equipment. It is also easy to fit into a busy schedule.

Squatting during labor may help open your pelvic outlet to help your baby descend, so practice squatting during pregnancy. To do a squat, stand with feet shoulder width apart and slowly lower into a squat position. You should keep your back straight, heels on the floor and your knees shouldn’t protrude in front of your feet. Hold the squat for 10 to 30 seconds; you can rest your hands on your knees.

Then slowly stand back up, pushing up from your knees with your arms, if you need to. Repeat this 5 times working up to more.

Pelvic tilts strengthen the muscles in your abdomen and help alleviate back pain during pregnancy and labor. To do pelvic tilts get on your hands and knees. Tilt your hips forward and pull your abdomen in. Your back should slightly round. Stay in this position for a few seconds then relax without letting your back sag. Repeat a couple of times, working up to 10.

What are the benefits of exercise during pregnancy?

Exercising for 30 minutes on most, or all, days can benefit your health during pregnancy. Exercising for just 20 minutes, 3 or 4 days a week, is still beneficial, as well. The important thing is to be active and get your blood flowing.

To have success in completing exercises during pregnancy, it is a good idea to plan the days and times during the week when you will exercise. As shown in the photo above, prenatal yoga  is a great, low impact exercise that can be highly beneficial for pregnant women.

Here are some of the benefits from exercise during pregnancy you may experience:

  • Helps reduce backaches, constipation, bloating, and swelling
  • May help prevent, or treat, gestational diabetes
  • Increases your energy
  • Improves your mood
  • Improves your posture
  • Promotes muscle tone, strength, and endurance
  • Helps you sleep better
  • Regular activity also helps keep you fit during pregnancy and may improve your ability to cope with labor. This will make it easier for you to get back in shape after your baby is born.