It's important to be on the lookout for any signs of a urinary tract infection while you're pregnant. While it's not very serious, and can be easily treated, it's a complication you can do without.
An infection may cause you to urinate more frequently, but this is also a symptom of early pregnancy so can be hard to spot. If, however, you also have stinging or discomfort when you actually urinate, lower abdominal pain, or even blood in the urine you may have developed a urinary tract infection. These infections are very common in women in general, because the urethra (tube which carries urine from the bladder to the outside) is very close to the anus and so bacteria do not have far to travel to create an infection.
In pregnancy, there are high levels of the hormone progesterone; this relaxes the tubes of the urinary system making it even easier for bacteria to enter and infect the bladder or even the kidneys. It is very important that if you have the symptoms of a urinary tract infection that your doctor tests your urine. In general, urinary tract infections are easily treatable in pregnancy. If there is an infection, you will be prescribed antibiotics that are safe to take in pregnancy. The infection must be treated because, if left, it may cause damage to your kidneys.