What are infections during pregnancy?

Infections during pregnancy

Many women may have a pregnancy that is normal and healthy. But, pregnancy could also make women more prone to certain kinds of infections. Also, pregnancy may make these infections more severe than they would be otherwise. During pregnancy, even mild infections can lead to major illness.

Some infections occurring during pregnancy pose a risk mainly to the mother. Others that can be transmitted to the fetus present serious risks for the baby as well. Some infections during pregnancy could even lead to miscarriage, birth defects, preterm labor, or maternal death. To make it worse, the drugs used to treat infections can result in serious side effects, particularly for the unborn child.

Why Are Pregnant Women More Susceptible to Infection?

Pregnancy affects every physiological system in the body. Changes in immune function and hormonal balance can make you more susceptible to infections and other serious complications. Labor and delivery are especially the most vulnerable times for both you and your baby.

Effects of Pregnancy on Immunity

The immune system protects the body against invaders, ranging from bacteria, viruses, and other probable causes of infection to cancer cells or transplanted organs.

While fighting infection, the body depends on several layers of defense. These include general barriers, like the skin and mucous membranes (these line body cavities that open to the exterior, namely the mouth, nose, as well as reproductive organs) as well as the cells whose job it is to swallow and destroy bacteria or to kill the infected cells. The immune system includes cells that identify specific antigens (substances which invoke an immune response) and cells which produce antibodies to attack antigens.

During pregnancy, your immune system changes so that it can protect both you as well as your baby from disease. Different parts of the immune system are enhanced while others are suppressed, resulting in a balance that helps in preventing infection in the fetus without compromising the defenses that are responsible to keep you healthy as well.

Changes in a woman's immune system during pregnancy are as follows:

• Increased production of macrophages (cells destroying bacteria). This improves antibody response and also helps to protect you against bacteria. However, they do not guarantee protection against bacterial infections;
• Decreased activity of NK cells ("natural killer" white blood cells that kill cells infected with a virus or are part of a tumor);
• Decreased activity of T cells, which helps to control infections caused by viruses;
• Decreased production of cytokines (these are released from immune cells to recruit other cells to help fight infection).

Infections Related to Mechanical and Hormonal Changes

In addition to immunologic changes that occur during pregnancy, hormonal changes can dispose you to infection. These effects are most pronounced in urinary tract, which is made up of the kidneys (organs producing urine), ureters (tubes carrying urine from the kidneys to the urinary bladder), bladder (where the urine is stored), and urethra (tube which transports urine out of the body).

The uterus enlarges during pregnancy and compresses the ureters. In the meantime, increased secretion of hormone progesterone relaxes the ureter and the bladder muscles. Due to this, urine may stay in the bladder for too long, increasing your susceptibility to urinary tract infections (UTIs).

Candidiasis (yeast infection) is another example; the result of increased estrogen in the reproductive tract disposes you to frequent yeast infections.

And, as your lungs contain more fluid during pregnancy and the pressure on the lungs from the abdomen makes it harder to clear the fluid, you are also more likely to develop pneumonia. This is due to the extra fluid that stimulates bacterial growth and hinders the body's ability to defend against infection.