You'll be giving a urine sample at each prenatal visit for urinalysis. Your provider's office or lab will test your urine for ketones, protein, and glucose at each visit, and may also check for the presence of any bacteria. Depending on the protocol followed in your provider's office, you will be asked either to bring a fresh urine specimen to your appointment or provide one upon your arrival.

Ketones

Ketone bodies are substances produced when the body is getting insufficient fuel from food intake and has to metabolize fat for energy. The result is a process known as ketosis, and the resulting ketones spill into the urine. Ketones may appear in pregnancy if you're suffering from severe nausea and vomiting, and they are a sign that you may require intravenous nutrition. They can also be a byproduct of gestational diabetes when blood sugars get too high (above 200 mg/dL), and can lead to a rare but potentially life-threatening complication called diabetic ketoacidosis (DKA).

Your urine test is a good excuse to get some of those extra fluids your body and the baby need right now. Down a bottle of drinking water on the way to your checkup so you can easily provide a sample, but don't overdo it or you may not make it without a pit stop.

The ketone test is generally performed with a reagent test strip, in which a strip of chemically treated paper is dipped in your urine sample and then matched against a color chart for the presence of ketones. Test strips allow your provider or her staff to get almost instantaneous results.

If you have gestational diabetes, you will probably be prescribed a vial of ketone strips (Ketostix) for home use. Your provider will instruct you in their proper use. (Appendix A has further information on gestational diabetes and DKA.)

Protein

Excessive protein (albumin) in the urine can be a sign of preeclampsia (also known as toxemia). It is also a possible indication of urinary tract infection (UTI) or of renal (kidney) impairment from chronic hypertension and/or diabetes. The presence of white blood cells in urine can be an indication of infection as well.

Your provider will again use a test strip to check for protein. If the strip is positive, it indicates that protein levels above 30 mg/dl are detected, which is considered more than the trace amount normally present in urine. A positive protein strip is an indication for further testing with the more specific twenty-four hour urine test.

In a twenty-four hour urine test, you'll be given a special container in which to collect your urine, and you'll be asked to keep the sample refrigerated during the collection period (which ought to do wonders for your appetite). In a nonpregnant woman, 150 mg or less of total protein excreted in a day is considered normal; pregnant women typically excrete more, and a normal test in pregnancy is less than 300 mg for a twenty-four hour period.

If preeclampsia is suspected, your provider will probably order additional tests, including a blood draw, ultrasound, and fetal monitoring. (See Appendix A for more on this condition.)

Glucose

Glucose (or sugar) in the urine (called glucosuria) can be a sign of gestational diabetes mellitus (GDM). It's normal to spill a small amount of sugar into the urine in pregnancy, but consistently high levels along with other risk factors raise a red flag that GDM may be present. Again, test reagent strips (that is, Diastix, Clinistix) are used for screening. If your doctor suspects gestational diabetes, he will order a one-hour glucose challenge test (1°GCT). (See the section on “Blood Work” in this chapter.)

Urine Culture

Your urine will be analyzed and cultured for the presence of bacteria at your first prenatal visit and again in the course of pregnancy if symptoms appear of a urinary tract infection (for example, burning during urination, strong-smelling urine). If you have certain conditions such as sickle cell anemia, a urine culture may be repeated throughout your pregnancy.