Background: Females are prone to urinary tract infections (UTIs) due to estrogen fluctuations affecting vaginal flora. While menstruating, increased fluid consumption to support urination frequency and void volume may be important, as the urethra and urinary tract are more predisposed to bacteria, particularly UTI pathogens. Aim: This study aimed to investigate the impact of hydration on urinary tract health during menstruation among underhydrated premenopausal women. Methods: Thirteen females participated in a 60-day 2 × 2 randomized crossover trial to evaluate the effectiveness of consuming ≥2.2 L of total beverage fluid intake, with 1.9 L being water, (intervention, INT) and maintaining habitual fluid intake (control, CON) on two subsequent menses. Participants completed fluid and urination diaries at days 2 and 5 after the onset of bleeding (day 1) to determine the fluid amount consumed and urination frequency. Urine concentration was assessed in afternoon (days 2 and 5) and uropathogenic bacterial activity in first-morning (days 3 and 6) urinations. General linear models assessed differences in bacterial and hydration outcomes. Results: The intervention led to a 62% mean total fluid increase, INT 3.0 ± 1.1 L and CON 1.9 ± 0.9 L, p < 0.001, = 0.459. Urination frequency was greater and urine concentration less in the INT to CON, all ps < 0.05, range = 0.023-0.019. Only four cultures detected uropathogenic bacteria, with no patterns between conditions or days, making it difficult to determine the intervention's effectiveness. Conclusion: Fluid intake increased, and hydration status improved. No differences in uropathogenic bacterial activity were seen between the hydration and control conditions.
Keywords: Urinary tract infection; cystitis; fluid intake; hydration; menstruation; prevention.