From the Guidelines
Urinary tract infections (UTIs) in the first trimester of pregnancy should be treated promptly with nitrofurantoin (100 mg twice daily for 5-7 days) or cephalexin (500 mg four times daily for 5-7 days) to prevent complications like pyelonephritis, preterm labor, and low birth weight. The recommended treatment is based on the guidelines from the Infectious Diseases Society of America 1 and the U.S. Preventive Services Task Force 1. It is essential to obtain a urine culture before starting antibiotics to confirm the diagnosis and ensure appropriate treatment. Asymptomatic bacteriuria should also be treated in pregnancy as it can progress to symptomatic infection, with a significant reduction in the incidence of symptomatic maternal urinary tract infections and low birthweight 1.
Key Considerations
- Avoid trimethoprim in the first trimester due to potential folate antagonism, and fluoroquinolones and tetracyclines are contraindicated throughout pregnancy.
- Increased fluid intake, urinating before and after intercourse, and proper wiping technique (front to back) can help prevent recurrence.
- Follow-up urine culture after completing treatment is recommended to ensure resolution of the infection.
- UTIs are common during pregnancy due to hormonal changes that relax the urinary tract muscles and the physical pressure of the growing uterus on the bladder.
Screening and Treatment
- All pregnant women should provide a clean-catch urine specimen for a screening culture at 12 to 16 weeks' gestation or at the first prenatal visit, if later 1.
- Pregnant women with asymptomatic bacteriuria should receive antibiotic therapy directed at the cultured organism and follow-up monitoring 1.
From the Research
UTI in First Trimester
- UTIs are the most common infection among pregnant women, affecting approximately 2% to 15% of women, with asymptomatic bacteriuria (ASB) affecting 2% to 7% of pregnant women 2.
- The risk of UTI is higher in pregnant women due to physiological changes related to pregnancy 2.
- ASB has been associated with an increased risk of acute pyelonephritis, preterm birth, and low birth weight if left untreated 2, 3.
- Treatment of ASB has been shown to reduce the incidence of low birth weight and preterm birth, justifying screening practices for ASB with a single urine culture in the first trimester 2.
- Recommended antimicrobials for the treatment of ASB include a short course of β-lactams, nitrofurantoin, or fosfomycin 2.
- Acute pyelonephritis has been associated with increased maternal complications and preterm delivery, with preferred antimicrobials including amoxicillin combined with an aminoglycoside, third-generation cephalosporins, or carbapenems 2.
Management of UTI in Pregnancy
- The management of UTI in pregnancy involves separating pregnant women into two groups: those with asymptomatic bacteriuria and those with symptomatic UTI 4.
- For asymptomatic bacteriuria, a single dose of an antimicrobial to which the organism is susceptible is recommended, while for symptomatic UTI, amoxicillin 500 mg tid for three days is recommended 4.
- Urine cultures should be repeated seven days following therapy to assess cure or failure 4.
- Current treatment options for UTIs due to antibiotic-resistant Gram-negative bacteria include nitrofurantoin, fosfomycin, pivmecillinam, fluoroquinolones, and β-lactams 5.
Prevention of UTI-Related Complications
- Screening for ASB with a single urine culture in the first trimester can help prevent UTI-related complications such as preterm birth and low birth weight 2.
- Antibiotic prophylaxis may be introduced in some patients to prevent recurrent UTIs 6.
- Urinary tests, such as urine culture or new technologies such as high-throughput DNA sequence-based analyses, can be used to improve antenatal screening of pregnant women and prevent UTI-related complications 3.