Bacterial Infections


The information provided below is for readers based in the United States of America. Readers outside of the United States of America should seek the information from local sources.

What are bacterial infections?

A bacterial infection is any condition resulting from infection of a part of the body with bacterial species that are not normally present in that environment. This can mean infection of a part of the body that is normally sterile (lacking microorganisms), or that normally contains a microbiome, a community of microorganisms, most of which are bacteria. Bacterial infections that occur fairly commonly in healthy pregnant women include bacterial vaginosis (BV), urinary tract infections (UTIs), and Group B streptococcus (GBS) infection.

BV is characterized by a discharge from the vagina, resulting from overgrowth of bacteria that do not typically dominate the vaginal microbiota, the various microbial species that normally inhabit your vagina. A UTI is an infection with bacteria that usually starts in the lower urinary tract (bladder and urethra). GBS is carried in the lower urinary tract, intestines, or genital area and normally does no harm in adults, but a GBS infection during pregnancy can potentially harm the baby.

How common are bacterial infections in pregnancy?

Bacterial infections are extremely common during pregnancy. BV, for instance, is the most common infection in the lower genital tract in women of reproductive age and may develop in up to one-third of pregnancies. As many as 13 percent of pregnant women are reported to have bacteria in their urine, although not all cases have symptoms. Approximately 15 – 35 percent of pregnant women have GBS in their vagina and/or rectum, but most of these women do not give birth to infants with GBS disease.

How are bacterial infections diagnosed?

The various bacterial infections are diagnosed through a series of procedures beginning with your report of symptoms, followed by your doctor performing a pelvic exam. In the case of BV, the pH of your vagina is tested to see if it is higher than normal. Your vaginal secretions will be sampled and tested under the microscope for the presence of what is called clear cells, which are vaginal cells covered with bacteria, which give the cells a very distinct look. Tests for bacteria and their identities are carried out on urine samples, vaginal samples, and in some cases rectal samples to diagnose other bacterial infections.

Do bacterial infections cause problems during pregnancy?

GBS usually does not cause problems to the healthy pregnant woman herself.

In addition to causing an unpleasant, foul-smelling vaginal discharge, BV that develops during pregnancy appears to increase the risk of spontaneous abortion (miscarriage), preterm labor and preterm delivery, preterm premature rupture of membranes (your water breaks too early, which can be a trigger for preterm labor), chorioamnionitis (infection and inflammation of the membranes surrounding the developing baby). Having BV can also increase your risk for pelvic inflammatory disease. Additionally, BV can make it easier to spread human immunodeficiency virus (HIV) if you have that.

UTI from a bacterial species called E. coli can cause hemolytic uremic syndrome (HUS), a very serious condition in which kidneys and sometimes other organs are damaged from blood clots. At the same time, there can be serious bleeding, anemia, breathing difficulty, and possibly heart failure. A UTI can be very minor such that you have no symptoms, but it can cause you to have to pee more. If the UTI with symptoms is not diagnosed, it can spread upward to the kidney, causing a serious condition called pyelonephritis. This can damage the kidneys and produce an infection throughout the body.

Does bacterial infections during pregnancy cause problems for the baby?

BV can trigger spontaneous abortion (miscarriage), and also can trigger preterm labor and preterm delivery, both directly and by causing any of the following other problems: preterm premature rupture of membranes, chorioamnionitis, endometritis, surgical wound infections. A small fraction of women who carry GBS in the rectum and/or vagina give birth to infants with GBS, causing 1- 2 cases in 1,000 births of neonatal GBS disease. Such infants develop fever, feeding and breathing difficulties, irritability (cry easily even when not hungry) and cyanosis (bluish color to the skin), all of which can threaten life.

A UTI will not harm the baby, so long as it remains limited to the lower urinary tract. If the infection is ignored and then spreads upward to the kidney, this results in high fever, risks serious kidney damage, and could lead to infection throughout the body. All of these complications are potentially very harmful first to you, and also to the baby as they can lead to spontaneous abortion, stillbirth, premature delivery, low birth weight, and other serious outcomes.

What to consider about taking medications when you are pregnant:

  • The risks to yourself and your baby if you do not treat the bacterial infection
  • The risks and benefits of each medication you use when you are pregnant
  • The risks and benefits of each medication you use when you are breastfeeding

What should I know about using medication to treat bacterial infections during pregnancy?

Often, bacterial infections during pregnancy require treatment with antibiotic medications. The treatment of choice for BV, for example, is metronidazole or clindamycin. In most cases, there are choices among antibiotics and a drug can be chosen that is safe for pregnancy. If you develop a fever as a result of a bacterial infection, you can treat the fever with acetaminophen or paracetamol, both of which very low-risk medications.

Who should NOT stop taking medication for bacterial infections in pregnancy?

Everybody who is given antibiotics for a bacterial infection needs to complete the course of therapy. Otherwise, you and the baby are at greater risk for severe complications. As for the fever medications, you should take them as needed, because fever itself can harm the baby.

What should I know about choosing a medication for bacterial infections in pregnancy?

You may find Pregistrys expert reports about the individual medications to treat bacterial infections here. Additional information can also be found in the sources listed at the end of this report.

What should I know about taking a medication for bacterial infections when I am breastfeeding?

Antibiotics can be chosen that minimize risk to a nursing infant. Metronidazole and clindamycin, used for BV for instance, are both considered to be very safe in nursing mothers. In some cases, such as an upper urinary tract infection or hemolytic-uremic syndrome (HUS), the antibiotic choices are more limited, but you will be too ill to breastfeed anyway in such cases.

What alternative therapies besides medications are there to treat bacterial infections during pregnancy?

many cases, antibiotic treatment is the treatment of choice for a bacterial infection, an example being BV, which responds very well to metronidazole or clindamycin, without major risk from those drugs. The same is true of upper urinary tract infections, which always require antibiotics. In other case, treatments other than medication constitute the treatments of choice. One example of the latter is HUS, for which the treatment of choice is a procedure called plasma exchange.

What can I do for myself and my baby when I have a bacterial infection during pregnancy?

Take your medication if indicated by your physician. Stay in contact with your physician and report new symptoms and effects of the medication, as it is possible that your medication may need to be changed.

Resources for bacterial infections during pregnancy:

For more information about bacterial infections during pregnancy, contact (800-994-9662 [TDD: 888-220-5446]) or read the following articles:


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Last Updated: 28-02-2020
General information

It is very common for women to worry about having a miscarriage or giving birth to a child with a birth defect while they are pregnant. Many decisions that women make about their health during pregnancy are made with these concerns in mind.

For many women these concerns are very real. As many as 1 in 5 pregnancies end in a miscarriage, and 1 in 33 babies are born with a birth defect. These rates are considered the background population risk, which means they do not take into consideration anything about the health of the mom, the medications she is taking, or the family history of the mom or the baby’s dad. A number of different things can increase these risks, including taking certain medications during pregnancy.

It is known that most medications, including over-the-counter medications, taken during pregnancy do get passed on to the baby. Fortunately, most medicines are not harmful to the baby and can be safely taken during pregnancy. But there are some that are known to be harmful to a baby’s normal development and growth, especially when they are taken during certain times of the pregnancy. Because of this, it is important to talk with your doctor or midwife about any medications you are taking, ideally before you even try to get pregnant.

If a doctor other than the one caring for your pregnancy recommends that you start a new medicine while you are pregnant, it is important that you let them know you are pregnant.

If you do need to take a new medication while pregnant, it is important to discuss the possible risks the medicine may pose on your pregnancy with your doctor or midwife. They can help you understand the benefits and the risks of taking the medicine.

Ultimately, the decision to start, stop, or change medications during pregnancy is up to you to make, along with input from your doctor or midwife. If you do take medications during pregnancy, be sure to keep track of all the medications you are taking.

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