Urine infection in pregnancy

Understanding the urinary tract

There are two kidneys, one on each side of the tummy (abdomen). They make urine which drains down tubes called ureters into the bladder. Urine is stored in the bladder. Urine is then passed out through a tube called the urethra when we go to the toilet.

Side view of female genitals and cross-section diagram of urinary tract

What is a urine infection?

A urine infection is caused by bacteria which get into the urine. Usually the bacteria have come from the skin, and travelled up the urethra into the bladder.

What are the symptoms of a urine infection?

The symptoms may depend on how far the bacteria have travelled. They include:

• Asymptomatic bacteriuria. In this situation bacteria are found in the urine but are not causing any symptoms. It is only found because the urine is tested. This does not usually require treatment but asymptomatic bacteriuria does need treating in pregnancy.

• Bladder infection (cystitis). This is common, both in pregnant and non-pregnant women. Typical symptoms are pain when on passing urine and passing urine more often, frequently in small amounts. There may also be other symptoms such as pain in the lower tummy (abdomen), blood in the urine, and a high temperature (fever).

• Kidney infection (pyelonephritis). This is uncommon but may occur as a complication from cystitis or asymptomatic bacteriuria. It is usually a more serious infection. Some or all of the possible symptoms may occur, which include:

  • Pain in the side (loin) over your kidney.

  • Having a high temperature.

  • Feeling sick (nausea).

  • Being sick (vomiting).

  • Diarrhoea.

  • Blood in the urine.

  • Symptoms of cystitis as above.

  • Feeling generally unwell.

What causes a urine infection?

Most urine infections are caused by bacteria which come from the bowel. They cause no harm in your bowel but can cause infection if they get into other parts of the body. Some bacteria lie around the back passage (anus) after passing a stool (faeces). These bacteria can sometimes travel to the urethra and into the bladder. Some bacteria thrive in urine and multiply quickly to cause infection.

Women are more prone than men to urine infections, as their urethra is shorter and opens nearer the anus.

Pregnant women are more prone than non-pregnant women to urine infections. This is partly due to the hormonal changes of pregnancy which affect the urinary tract and tend to slow down the flow of urine. It also may be that the enlarged womb (uterus) presses on the bladder and prevents it draining as fully. If urine does not drain quickly from the bladder, germs are more able to multiply and cause an infection.

Less commonly there may be other causes of a urine infection. A catheter may be required during a hospital admission; this can make urine infections more likely.

Can a urine infection affect my pregnancy?

A kidney infection when pregnant can cause people to feel very unwell. If left untreated, it may also cause problems such as early labour and/or a baby of low birthweight.

A kidney infection is uncommon but may develop as a complication from a bladder infection (cystitis) or from a urine infection. There may be no symptoms at first (asymptomatic bacteriuria).

When is my urine checked during pregnancy?

• Urine is usually tested early in pregnancy. A midwife will ask for a urine sample. Treatment is advised if any bacteria are found, even with no symptoms. If bacteria are found, regular routine urine tests are usually offered throughout the pregnancy.

• A urine sample is usually tested at each of the antenatal checks. How often this is depends on how the pregnancy is progressing and whether there are any problems or complications.

• Urine should also be tested if any symptoms of bladder infection (cystitis) or kidney infection develop at any stage during pregnancy.

What is the treatment for a urine infection in pregnancy?

Antibiotics

There are several different types of antibiotic that can help. The midwife will choose the type most likely to help. A seven-day course of an antibiotic is the usual treatment in pregnancy. Any symptoms will usually improve within a few days.

It is very important to complete the course of antibiotics. The antibiotics used to treat urine infections in pregnant women are safe to take in pregnancy and will not harm the baby.

A medical review should be sought if the symptoms do not go or if they get worse. Some bacteria are resistant to some antibiotics. This can be identified from tests done on the urine sample. A change of antibiotic is needed if the bacteria is found to be resistant to the first antibiotic.

Note: Treatment with an antibiotic is usually advised for pregnant women, whether or not there are symptoms. This is a little different to the treatment of bladder infection (cystitis) in non-pregnant women. Not having any treatment is an option in non-pregnant women, as cystitis often goes without treatment.

Painkillers

Paracetamol will usually ease any pain, discomfort, or high temperature (fever).

Drinking fluids

With cystitis, the traditional advice is to flush out the bladder by drinking lots of fluid. However, there is no proof that this is helpful when you have cystitis. Some doctors feel that it does not help, and drinking lots may just cause more (painful) toilet trips.

Therefore, it is difficult to give confident advice on whether to drink lots or just to drink normally with mild symptoms of cystitis. However, if there is also a fever and/or a general feeling of being "unwell", having plenty to drink helps to prevent lack of fluid in the body (dehydration).