Elevated White Blood Cells in Urine During Late Pregnancy: Causes, Prevention, and What to Do Next
Discovering elevated white blood cells (WBCs) in a urine test during the third trimester can be concerning for expectant mothers. This condition often signals a potential urinary tract infection (UTI), which is relatively common in late pregnancy. As the uterus expands to accommodate the growing baby, it can exert pressure on the bladder and urethra, slowing urine flow and creating an environment where bacteria can thrive. This anatomical shift increases the risk of developing infections that may lead to higher WBC counts in urine samples.
Common Causes of High White Blood Cells in Prenatal Urine Tests
While a true UTI is one explanation, another frequent cause of falsely elevated white blood cells is sample contamination. During pregnancy, many women experience increased vaginal discharge, especially if there's an underlying yeast or bacterial vaginitis. If this discharge—particularly when inflammatory—mixes with the urine sample, it can introduce white blood cells and epithelial cells, leading to misleading lab results.
How Contamination Affects Test Accuracy
Laboratory technicians may observe numerous epithelial cells under the microscope, which strongly suggests that the sample was contaminated with vaginal secretions. This scenario doesn't necessarily indicate a urinary infection but highlights the importance of proper collection techniques. To avoid false positives, pregnant women should always clean the external genital area before urination and collect a midstream urine sample—discarding the first and last portions of the stream.
Symptoms That May Indicate a Real Infection
If you're experiencing symptoms such as frequent urination, urgency, burning sensation during urination, lower abdominal discomfort, or cloudy/foul-smelling urine, these could point to an actual urinary tract infection. Left untreated, UTIs in pregnancy can progress to more serious conditions like kidney infections (pyelonephritis), which pose risks to both mother and baby, including preterm labor.
Why Timely Medical Evaluation Matters
Whenever abnormal urine results appear, it's essential to consult your obstetrician promptly. They will assess your symptoms, review your medical history, and possibly order a urine culture to confirm whether an infection is present. Based on the findings, they might prescribe pregnancy-safe antibiotics to clear the infection and prevent complications.
Best Practices for Accurate Urine Testing in Late Pregnancy
To ensure reliable test results, follow these evidence-based tips:
- Wash your hands and clean the vulvar area with sterile wipes before urinating.
- Begin urinating into the toilet, then pause and collect the middle portion of the stream in the sterile container.
- Avoid touching the inside of the cup or placing it in contact with skin.
- Deliver the sample to the lab within one hour or refrigerate it temporarily if needed.
By adhering to proper hygiene and collection methods, you reduce the chance of false abnormalities and help your healthcare provider make accurate decisions about your prenatal care.
Final Thoughts: Stay Proactive About Urinary Health
Elevated white blood cells in a urine test during late pregnancy don't automatically mean you have an infection. However, they do warrant attention. Whether due to contamination or a genuine UTI, understanding the root cause allows for appropriate action. Always communicate openly with your prenatal care team, follow their guidance, and never ignore persistent urinary symptoms—even if they seem mild. Staying proactive supports a healthier, safer journey toward delivery.