Urine tests provide your doctor or midwife with important information about diseases or conditions that could potentially affect you or your growing baby. That's why at each prenatal visit, you’ll be asked to give a urine sample as part of your regular exam.

This sample is used to help determine if you have diabetes, kidney disease, or a bladder infection by measuring the levels of sugar, protein, bacteria, or other substances in your urine. The test is routine and painless and could prevent a lot of trouble down the road.

Urine can be collected any time of day. You will most likely be given a sterile cup to collect a sample before your exam. Before urinating, use a sterile towelette to wipe your genitals from front to back, and then release a small amount of urine into the toilet -- this prevents the sample from being contaminated with bacteria or other secretions that may invalidate the results. Put the container in your urine stream, and collect at least one to two ounces.

This sample is then checked with chemically treated testing strips or sticks, and the results are usually available right away. If more analysis is necessary, your urine may be sent to a lab for additional assessment.

Sugar
Typically, there is very little or no sugar (glucose) in urine. But when blood sugar levels in the body are too high, excess sugar can end up in the urine. This can be seen with gestational diabetes, a form of diabetes that only develops during pregnancy. It occurs when pregnancy hormones disrupt the body's ability to use insulin, a chemical that turns blood sugar into energy.

A doctor often orders a blood test for diabetes early in your pregnancy if he or she knows you have other risk factors, like a personal or family history of gestational diabetes. And most doctors routinely screen for diabetes with blood tests between weeks 24 and 28 even if you have no known risks for diabetes. The screening test usually used is the one-hour oral glucose test, in which blood is tested for glucose one hour after drinking a sugary solution.

Each year, about 135,000 American moms-to-be are diagnosed with gestational diabetes but don't know it because it frequently causes no symptoms. If you have gestational diabetes, it can often be controlled through diet and exercise and daily self-testing of blood sugar. Some women take insulin as part of their treatment plan.

Remember that most women with diabetes deliver healthy babies. But left unchecked, babies of mothers with gestational diabetes are more likely to weigh more than 9 pounds, sometimes making vaginal delivery difficult. Even more important, uncontrolled glucose levels throughout pregnancy can also lead to an increased risk of heart, kidney, and spine defects in your newborn.

Even if your urine test results are fine, most women also have blood drawn for a glucose test between weeks 24 and 28. But don't fret: One unusually high sugar level doesn't mean you have diabetes -- having a sweet drink or large meal too close to the time of the test can also cause a high reading. Your doctor will order a follow-up test to see if you truly have gestational diabetes.

Protein
Protein in urine (proteinuria) can indicate a urinary tract infection (UTI), a kidney infection or chronic kidney disease. When proteinuria develops later in pregnancy, it can be an early sign of preeclampsia, a pregnancy-related condition that can cause high blood pressure after the 20th week of pregnancy, and increase the risk of serious complications for mom and baby. Preeclampsia complicates about 7 percent of all pregnancies, and women with preeclampsia usually need immediate treatment to prevent problems with their health and delivery.

If you have proteinuria and your blood pressure is in the normal range, your health-care provider may order a urine culture to determine if an infection is causing the proteinuria. The culture can also identify the bacteria, allowing your provider to target the infection with the right antibiotic. You may have to wait 48 to 72 hours for the results. In the meantime, your provider may opt to start you on antibiotics. (Rest assured, several types of antibiotics are considered safe for pregnant women.) Your doctor may also ask you to collect urine over 24 hours to quantify the amount of protein in your urine.

If you have preeclampsia, your doctor will monitor you and your baby and may recommend bed rest to lower your blood pressure. Once doctors diagnose preeclampsia, they often recommend inducing labor or performing a caesarean once they know the baby is viable. The problem is when doctors are not sure if it’s preeclampsia. In these cases, more tests are ordered, and women sometimes have to be admitted to the hospital for observation until the diagnosis is confirmed or until the baby is delivered.

If it looks like you or your baby is in danger, your doctor may recommend inducing labor or performing a cesarean section ahead of schedule. Delivery is the only "cure" for preeclampsia.

Bacteria
The presence of bacteria in urine is a clear sign of a UTI. As many as 8 percent of pregnant women get UTIs, but many don't have any symptoms. However, a symptomless infection can still spread to the kidneys and cause significant problems for you or your baby. Treated quickly and properly, UTIs rarely lead to further complications. But left untreated, they can damage your kidneys and elevate your risk of having a low birthweight or premature baby.

A urine test strip does not detect bacteria, but it can detect an enzyme that is a sign of a urinary tract infection. A test strip can also detect nitrites in the urine, which are secreted by some bacteria.

If this test is positive, practitioners usually recommend following up with a urine culture to confirm the presence of bacteria and which antibiotics will work best. Pregnant women (even if they don't have symptoms) who have bacteria in their urine should always be treated with antibiotics. Although several types of antibiotics are considered safe for pregnant women, the journal American Family Physician warns against using sulfonamides in the third trimester. If you have questions, consult with your doctor before taking any antibiotics.

In fact, doctors usually order a urine culture at the beginning of a pregnancy so that they can identify and treat any symptomless bacterial infections that could cause complications later on.

Ketones
When fat is broken down for energy instead of carbohydrates, the results are acidic byproducts known as ketones. If you have diabetes, large quantities of ketones in urine may indicate a harmful condition called ketoacidosis, which can lead to diabetic coma.

If exceptionally high levels of ketones are found in your urine, your doctor will investigate whether your eating or drinking habits are to blame. If a doctor determines that the presence of ketones in a pregnant woman's urine can be blamed simply on not eating enough, and they disappear after she eats, then hospitalization isn't necessary. If severe nausea and vomiting affect your ability to keep food or fluids down, you may need to receive nutrients through an intravenous line. Treatment for ketoacidosis, which can be an acute condition, usually takes place in a hospital.

Protein, sugar, bacteria, or ketones in your urine can spell trouble for you and your baby, but prompt testing and proper treatment can help prevent any problems. That said, the vast majority of pregnant women can breathe easy: Most urine test results reveal that all is well.

-- Sarah Henry is an award-winning health writer specializing in parenting and social issues. She was a staff writer for the Center for Investigative Reporting and has reported on health issues for Hippocrates, Time Inc. Health, the Washington Post, the Los Angeles Times Magazine, and television programs such as "60 Minutes" and PBS' "Health Quarterly."

References

First published June 28, 2005
Last updated March 13, 2008

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