What should I do if my urine is dark yellow and reduced in volume during the third trimester of pregnancy?

During the third trimester of pregnancy, it’s common for women to notice darker yellow urine and reduced urine output. This is often due to physiological changes—including increased blood volume, heightened renal perfusion, and compression of the bladder and ureters by the enlarging uterus—which can lead to more concentrated urine and a sensation of urinary frequency or incomplete emptying. However, it’s essential to distinguish normal adaptations from potential concerns.

First, assess hydration status: many pregnant individuals unintentionally underhydrate, especially if experiencing nausea, heartburn, or reduced appetite. Aim for approximately 8–10 cups (2–2.5 L) of fluids daily—preferably water, with limited caffeine (<200 mg/day) and avoidance of sugary beverages. Dark yellow urine that lightens after increasing fluid intake typically reflects mild dehydration rather than pathology.

That said, certain red flags warrant prompt medical evaluation: urine that is persistently tea-colored or brown; associated symptoms such as fever, flank pain, dysuria, or suprapubic discomfort; visible hematuria; decreased fetal movement; or signs of preeclampsia (e.g., new-onset headache, visual changes, epigastric pain, or sudden swelling). These may indicate urinary tract infection (UTI), intrahepatic cholestasis of pregnancy (ICP), acute fatty liver of pregnancy (AFLP), or gestational hypertension—conditions requiring timely diagnosis and management.

Routine prenatal care includes urinalysis at each visit; if asymptomatic bacteriuria is detected, treatment with pregnancy-safe antibiotics (e.g., nitrofurantoin or cephalexin) is indicated to prevent pyelonephritis. Additionally, avoid prolonged supine positioning in late pregnancy, as it can compromise venous return and renal perfusion—opt instead for left lateral decubitus positioning when resting.

If urine color and volume remain concerning despite adequate hydration—or if uncertainty persists—consult your obstetric provider for targeted assessment, including urinalysis, urine culture, serum liver enzymes, and renal function tests as clinically indicated.