Urinary tract infections in pregnancy

Abstract

Background: Urinary tract infections (UTIs) are the most common infection among pregnant women and have been associated with maternal and foetal complications. Antimicrobial exposure during pregnancy is not without risk. International guidelines recommend a single screen-and-treat approach to asymptomatic bacteriuria (ASB); however, this approach has been questioned by recent studies.

Objectives: The aim of this narrative review was to assess the pathophysiology, current risk factors and management of UTI during pregnancy, its impact on pregnancy outcomes, and to develop recommendations on the best use of antimicrobials.

Sources: PubMed, Cochrane database, and ClinicalTrials.gov.

Content: Owing to the physiological changes related to pregnancy, pregnant women are at higher risk of UTI. All types of UTIs combined have been estimated to affect approximately 2% to 15% of women. ASB affects 2% to 7% of pregnant women. Recent studies do not provide good-quality evidence for an association between ASB and acute pyelonephritis if ASB is untreated. There is low-to-moderate-quality evidence that treatment of ASB results in a reduction in the incidence of low birth weight and preterm birth, which justifies screening practices for ASB with only a single urine culture in the first trimester. If the clinician opts for treatment, a short course of β-lactams, nitrofurantoin, or fosfomycin should be favoured. Studies on cystitis during pregnancy are limited. Acute pyelonephritis has been shown to be associated with increased maternal complications and in some studies has also been associated with preterm delivery and low birth weight. Preferred antimicrobials for the management of pyelonephritis are amoxicillin combined with an aminoglycoside, third-generation cephalosporins, or carbapenems. Studies on recurrent UTIs during pregnancy are limited, making it difficult to draw conclusions regarding prophylactic measures.

Implications: Further research is required to understand the true incidence of ASB-related complications and the benefit and modalities of screening for ASB and to further explore prophylactic measures.

Keywords: Asymptomatic bacteriuria; Cystitis; Pregnancy; Pyelonephritis; Urinary tract infection.