At your OB-GYN visits, urine tests screen for several things at once: protein (a sign of preeclampsia), glucose (a flag for gestational diabetes), signs of urinary tract infections, and markers of dehydration or nutritional problems. The small cup you fill at each appointment feeds into a quick dipstick test that checks multiple health indicators in under a minute. Some of these screenings happen routinely, while others are ordered based on your symptoms or risk factors.
Protein: Screening for Preeclampsia
One of the primary reasons your urine is tested during pregnancy is to check for protein, which can signal preeclampsia, a potentially dangerous condition involving high blood pressure. The classic threshold for concern is more than 300 milligrams of protein in a 24-hour urine collection, or a protein-to-creatinine ratio of 0.3 or higher. A simple dipstick test at your appointment gives a rough estimate, but if the result is elevated, your provider will order more precise lab work to confirm.
Interestingly, both the U.S. Preventive Services Task Force and the American College of Obstetricians and Gynecologists have noted that routine protein dipstick testing isn’t strongly recommended for low-risk women. Some practices, including certain midwifery programs, skip routine urine protein checks entirely for patients without risk factors. If you do have risk factors for preeclampsia (such as high blood pressure before pregnancy, a history of preeclampsia, or carrying multiples), your provider is more likely to test your urine for protein at every visit.
Glucose: Flagging Gestational Diabetes
The dipstick also checks for sugar in your urine. When glucose shows up, it means your body isn’t processing blood sugar efficiently, which can be an early hint of gestational diabetes. A reading of 2+ or more on a single occasion, or 1+ on two or more occasions, typically triggers further blood testing.
That said, urine glucose alone is not used to diagnose gestational diabetes. It’s a rough screening tool. The definitive test is a glucose tolerance test, where you drink a sugary solution and have your blood drawn at timed intervals. If your urine keeps showing glucose, your provider will likely move to that blood-based test rather than relying on the dipstick.
Bacteria and White Blood Cells: Catching UTIs
Urinary tract infections are more common during pregnancy because hormonal changes slow the flow of urine through your system, giving bacteria more time to multiply. The dipstick tests for two markers of infection: nitrites (produced by bacteria) and leukocyte esterase (a sign of white blood cells fighting infection).
In pregnant women, a positive nitrite result is highly specific, meaning if it’s positive, there’s a very good chance infection is present. However, sensitivity is lower, around 46%, so a negative result doesn’t completely rule out a UTI. When either marker is positive, your provider will usually send the sample for a urine culture to identify the exact bacteria and choose the right treatment. This matters because even infections without symptoms (called asymptomatic bacteriuria) can lead to kidney infections or preterm labor if left untreated.
Ketones: Signs of Dehydration or Poor Nutrition
Ketones appear in your urine when your body starts burning fat for energy instead of carbohydrates. During pregnancy, this usually means you’re not eating or drinking enough, whether from severe morning sickness, dehydration, or prolonged vomiting. In cases of hyperemesis gravidarum (extreme nausea and vomiting during pregnancy), ketonuria is a common finding and helps providers gauge how severe the condition has become.
Ketones in your urine aren’t diagnostic on their own, but they influence treatment decisions. If your levels are high, your provider may recommend IV fluids, nutritional support, or in more serious cases, a hospital stay to get your hydration and calorie intake back on track.
Blood: Not Always a UTI
The dipstick can detect blood in your urine even when it’s not visible to the naked eye. During pregnancy, the most common cause is a urinary tract infection, but blood can also come from kidney stones, kidney inflammation, or simply increased pressure on the bladder as your uterus grows. Vaginal bleeding or discharge can sometimes contaminate the sample too, which is why your provider may ask you to use a clean-catch technique (wiping first and catching urine midstream).
A single trace of blood on a dipstick usually isn’t alarming, but persistent or significant amounts will prompt further investigation, including a urine culture or imaging if kidney stones are suspected.
Bilirubin: A Window Into Liver Function
Bilirubin is a waste product your liver processes. It doesn’t normally show up in urine, so when it does, it suggests your liver isn’t functioning as it should. During pregnancy, one condition this can point to is intrahepatic cholestasis, a liver disorder that causes intense itching, dark urine, and pale stools. Elevated bilirubin shows up in about 25% of cholestasis cases.
Bilirubin on a dipstick is a prompt for blood work, not a diagnosis. Your provider will check liver enzymes and bile acid levels to determine whether cholestasis or another liver issue is at play.
pH: A Subtle but Useful Marker
Urine pH measures how acidic or alkaline your urine is. During pregnancy, urine tends to run more alkaline than usual, averaging around 6.6 compared to roughly 5.95 after delivery. This shift is linked to changes in how your gut absorbs certain compounds during pregnancy. While pH alone rarely triggers a diagnosis, unusually acidic urine can point toward dehydration or metabolic stress, and very alkaline urine can sometimes indicate a UTI caused by specific bacteria.
Pregnancy Confirmation
If your pregnancy hasn’t been confirmed yet, one of the first urine tests your OB-GYN may run detects human chorionic gonadotropin, the hormone your body produces after a fertilized egg implants. Office urine tests typically detect this hormone at concentrations of 25 mIU/mL or higher, which is the same sensitivity as most over-the-counter home pregnancy tests. Blood tests can detect even lower levels and provide an exact measurement, which is why your provider may order blood work if there’s any ambiguity.
Drug Screening: Not Routine
Some people wonder whether their OB-GYN is also running a drug test on their urine sample. In most practices, the answer is no, not routinely. ACOG’s position is that urine drug screening should only be performed with your consent. A positive result should not be used to deny care, disqualify you from insurance coverage, or serve as the sole basis for family separation. If your provider does order a drug screen, they should discuss it with you beforehand. Practices vary by state and hospital system, so if this is a concern, you’re within your rights to ask directly what’s being tested.