15th July 2024

Urinary Tract Infections in Pregnancy

Urinary tract infections (UTIs) in pregnancy are potentially severe as they are associated with developmental delay, cerebral palsy and infant death. Please note that unlike in non-pregnant individuals, the presence of bacteria in the urine without symptoms – i.e. asymptomatic bacteriuria (ASB) – is not a benign condition in pregnancy, as it is a risk factor for pyelonephritis and premature labour. ASB should be treated with antibiotics.

NICE guidelines for antibiotics for UTIs in pregnancy are as follows:

• First line: nitrofurantoin – avoid at term due to risk of neonatal haemolysis or if significant renal impairment (pre-pregnancy eGFR <45 ml/min)
• Second line: amoxicillin 500mg three times a day for 7 days or cefalexin 500mg twice daily for 7 days

For ASB, nitrofurantoin, amoxicillin and cefalexin can all be used, based on culture/sensitivity results.

Trimethoprim, although commonly used to treat UTIs, is a folate antagonist and, therefore, should be avoided in the first trimester. Manufacturer advice is to avoid trimethoprim altogether in pregnancy. Other antibiotics to treat UTIs contraindicated in pregnancy include quinolones, such as ciprofloxacin and levofloxacin. Gentamicin should be avoided, due to a small risk of foetal ototoxicity.