Can a Urine Infection Cause Miscarriage in Early Pregnancy?

Pregnancy is an exciting time, but it can also raise questions about health conditions that could impact your baby. If you are pregnant, you may have heard of people miscarrying due to a urine infection. But what are the facts? We delve into the relationship between urinary tract infections (UTIs) and miscarriage and what the evidence suggests. Read on for accurate information to keep you safe and sound.

Understanding Urinary Tract Infections During Pregnancy

A urinary tract infection (UTI) is when bacteria get into your urinary system and start to multiply. Your urinary system is made up of your bladder, your kidneys, ureters, and urethra. When you're pregnant, your body changes in ways that make you more likely to get a UTI.

Women are most at risk of getting a UTI in their pregnancy during weeks 6-24. This is because your uterus gets bigger and puts more pressure on your bladder. Your bladder can't empty completely. Hormonal changes also slow the speed of your urine flow and allow bacteria to grow.

In the UK, about 1 in 3 women will have a UTI in their lifetime. During early pregnancy, UTIs are thought to affect about 8% of all pregnancies. UTIs can be mild bladder infections or more serious kidney infections.

Can a Urine Infection Cause Miscarriage?

Here is the short answer: a straightforward UTI typically does not directly cause miscarriage. The connection between urinary infections and pregnancy loss is more complex than many people realise.

Research shows that untreated UTIs can lead to serious complications that may increase miscarriage risk. When a bladder infection spreads to the kidneys or bloodstream, it can cause conditions like sepsis, which poses serious threats to both mother and baby.

A case report documented how untreated urinary infection can progress to septic miscarriage when bacteria spread throughout the body. This rare but serious situation develops when an infection goes without proper treatment.

Studies have examined the relationship between UTIs and pregnancy outcomes. Research published in Human Reproduction found that women with a history of UTIs were 2.5 times more likely to experience miscarriage compared to women without such history. The study looked at patterns rather than direct causation.

The key point is this: the infection itself rarely causes pregnancy loss, but the complications from untreated infections can. When bacteria reach the kidneys or bloodstream, they can trigger inflammation, fever, and systemic infections that threaten pregnancy.

How UTIs Progress During Pregnancy

Understanding the stages of urinary infections helps you recognise when to seek help.

1. Asymptomatic Bacteriuria (ASB): This condition means bacteria exist in your urine without causing symptoms. About 10% of pregnant women test positive for ASB during routine screening. Without treatment, approximately 25% will develop a symptomatic infection.

2. Cystitis (Bladder Infection): This is the most common type of UTI. Bacteria multiply in the bladder, causing discomfort during urination. When caught early, cystitis responds well to antibiotics and rarely causes pregnancy complications.

3. Pyelonephritis (Kidney Infection): This serious infection develops when bacteria travel from the bladder to the kidneys. Pyelonephritis is one of the most common conditions requiring hospitalisation among pregnant women. It can cause fever, severe back pain, and systemic illness.

   
   

Recognising UTI Symptoms in Pregnancy

Many UTI symptoms overlap with normal pregnancy changes, making them easy to miss. Watch for these signs:

• Burning or stinging sensation when urinating

• Frequent urge to urinate with only small amounts of urine

• Cloudy, dark, or foul-smelling urine

• Blood in your urine

• Lower abdominal or pelvic pain

• Pain during intercourse

More serious symptoms that require immediate medical attention include:

• High fever (above 38°C)

• Severe back or flank pain

• Chills or shaking

• Nausea and vomiting

• Feeling generally unwell or confused

Some women experience no symptoms at all, which is why routine early pregnancy testing forms part of standard antenatal care.

Why Pregnancy Increases UTI Risk

Several factors make expectant mothers more vulnerable to urinary infections.

Hormonal Changes

Progesterone relaxes the muscles in your urinary tract, slowing the flow of urine. This gives bacteria more time to multiply before being flushed out.

Physical Pressure

The expanding uterus puts pressure on the bladder and ureters. This can prevent complete bladder emptying, leaving residual urine where bacteria can grow.

Immune System Changes

Pregnancy naturally suppresses certain immune responses to prevent your body from rejecting the developing baby. This protective mechanism also makes you more susceptible to infections.

Changes in Urine Composition

During pregnancy, urine becomes less acidic and contains more glucose and amino acids. These changes create a more favourable environment for bacterial growth.

Potential Complications of Untreated UTIs

Prompt treatment prevents most complications, but understanding the risks helps you appreciate why early care matters.

Kidney Infection

When bladder infections spread upward, they can cause pyelonephritis. This condition requires hospitalisation and intravenous antibiotics. Left untreated, kidney infections can damage these organs and cause sepsis.

Preterm Labour

Studies show that women with UTIs during pregnancy face increased risk of preterm birth, with some research indicating 1.5 times higher likelihood. The inflammation and infection can trigger early contractions.

Low Birth Weight

Babies born to mothers with untreated UTIs may have lower birth weights. The infection can interfere with normal foetal development and nutrient transfer across the placenta.

Sepsis

In rare cases, bacteria enter the bloodstream, causing a life-threatening condition called sepsis. This can lead to organ failure and poses serious risks to both mother and baby.

Preeclampsia

Research indicates that urinary tract infections in the first trimester may be associated with increased risk of preeclampsia. This serious condition involves high blood pressure and organ damage.

Safe Treatment Options During Pregnancy

Antibiotics remain the most effective treatment for UTIs during pregnancy. Your healthcare provider will prescribe medications safe for both you and your developing baby.

First-Line Antibiotics

Nitrofurantoin is commonly prescribed during the first and second trimesters. It works well for bladder infections and has a strong safety record. Doctors typically avoid it near delivery due to a small risk of affecting the baby's red blood cells.

Amoxicillin and cephalexin are also safe choices throughout pregnancy. These antibiotics effectively clear infections without harming the foetus.

Treatment Duration

Most UTIs during pregnancy require a seven-day course of antibiotics, longer than the three-day courses often given to non-pregnant women. The extended duration ensures complete elimination of bacteria.

Fosfomycin

This antibiotic can be given as a single dose for uncomplicated bladder infections. Its convenience helps with medication compliance, though it should not be used for kidney infections.

Antibiotics to Avoid

Some medications commonly used for UTIs outside pregnancy are not safe during pregnancy. Trimethoprim, a folate antagonist, increases miscarriage risk in the first trimester. Fluoroquinolones can cause fetal cartilage damage. Your doctor will carefully select antibiotics that protect both you and your baby.

The Importance of Completing Treatment

It's important to finish all the antibiotics you've been prescribed, even if your symptoms get better after a few days. Stopping treatment early may leave some bacteria in your body and allow the infection to come back or become resistant.

Your healthcare provider will usually ask for a repeat urine sample one to two weeks after treatment to make sure the infection is gone. This is known as a "test of cure."

Prevention Strategies

You can take several steps to reduce your risk of developing a urine infection that causes miscarriage concerns during pregnancy.

• Stay Well Hydrated: Drink six to eight glasses of water daily. Adequate fluid intake helps flush bacteria from your urinary system before they can multiply.

• Practice Good Hygiene: Always wipe from front to back after using the toilet. This prevents bacteria from the rectal area reaching your urethra.

• Empty Your Bladder Regularly: Do not hold urine for long periods. When you feel the urge, use the toilet promptly. Try to empty your bladder completely each time. Leaning slightly forward or gently lifting your abdomen can help.

• Urinate After Intercourse: Emptying your bladder after sexual activity helps flush out any bacteria that may have entered the urethra.

• Choose Appropriate Clothing: Wear cotton underwear and avoid tight-fitting trousers. Breathable fabrics help keep the area dry, making it less hospitable to bacteria.

• Avoid Irritants: Scented soaps, bubble baths, and feminine hygiene products can irritate the urinary tract. Use plain, unscented products for intimate hygiene.

• Consider Cranberry Products: Whilst evidence is mixed, some studies suggest cranberry juice may help prevent bacteria from adhering to the bladder wall. Speak with your healthcare provider before adding supplements to your routine.

  
  

When to Contact Your Healthcare Provider

If you suspect a UTI during pregnancy, contact your doctor or midwife promptly. Do not wait to see if symptoms resolve on their own.

Seek immediate medical attention if you experience:

• High fever or chills

• Severe back or side pain

• Persistent vomiting

• Reduced foetal movement

• Signs of preterm labour, such as regular contractions

• Confusion or difficulty staying alert

These symptoms may indicate a more serious infection requiring urgent treatment.

The Role of Routine Screening

As part of your antenatal care you'll be asked to do regular urine tests so that infections can be picked up and treated early, even before you have symptoms. After the UK National Institute for Health and Care Excellence (NICE) changed its guidance on screening for asymptomatic bacteriuria, it's no longer routinely offered to all pregnant women.

Your midwife will evaluate your personal risk factors at your booking appointment. You may be offered screening if you have risk factors for preterm delivery, symptoms of infection, or markers of infection in your routine urine samples.

This means that women who need to be monitored will get the care they need, while women who are at lower risk won't be asked to do unnecessary testing.

Expert Care at myGynaePlus

myGynaePlus offers the full range of women’s health and maternity services, including the management of urinary tract infections (UTI) in pregnancy. Our London specialist gynaecologists and obstetricians understand how worrying it can be for expectant mothers to hear that a urine infection may cause miscarriage.

We are a women’s health clinic in West London, specialising in the full care and support for women throughout their pregnancy. This means from your first pregnancy scan all the way through your pregnancy to full antenatal care and monitoring of your pregnancy, including medical support and reassurance in our clinic. We offer a full assessment and treatment of your urinary tract infection so you can have a healthy pregnancy.

Our clinic is affiliated with major laboratories including The Doctors Laboratory. This means that we can send urine for testing and culture to help identify which bacteria you have and determine the most effective antibiotic to treat your infection.

Understanding Your Body's Signals

Learning to distinguish between normal pregnancy changes and potential problems empowers you to take action when needed. Frequent urination is common in pregnancy due to pressure on your bladder, but pain or burning during urination is not normal and deserves medical attention.

Trust your instincts. If something feels wrong, contact your healthcare provider. They would rather check and find nothing serious than have you delay seeking help for a condition that needs treatment.

Conclusion

In response to the question, “can a urine infection cause miscarriage?” The answer is not that simple. In many cases, uncomplicated urinary tract infections with appropriate treatment are not likely to lead to pregnancy loss. The real problem with urine infections is a case that is left untreated and the condition subsequently develops into something more serious like a kidney infection or sepsis.

The reason you are more likely to get a urinary tract infection during pregnancy is that there are some hormonal, physical, and immune changes that happen to your body which increase your risk. This is why it’s so important to spot the signs and symptoms early and to get treatment to ensure that your health and the development of your baby are not affected.

At myGynaePlus, our team of medical professionals have the skills, knowledge, and experience to support you with all aspects of your pregnancy, including any urinary tract infections. We’ll offer you a tailored treatment plan based on your condition, a range of diagnostic tests to identify your condition, and expert support throughout the course of your pregnancy.

If you are concerned that a urine infection could cause miscarriage, then contact myGynaePlus as soon as possible. With the advances in medical treatment today, there are safe and effective antibiotics that can clear up your infection without putting your pregnancy at risk. Your healthcare team are here to support you, so attend your antenatal appointments and if you do develop any symptoms then contact your doctor as soon as possible.

Frequently Asked Questions

Can a mild UTI directly cause a miscarriage?

A mild bladder infection typically does not directly cause miscarriage. Research shows that simple UTIs, when properly treated, pose minimal risk to pregnancy. The concern arises when infections go untreated and progress to more serious conditions like kidney infections or sepsis. These complications can trigger inflammation and systemic illness that may threaten pregnancy. Prompt antibiotic treatment prevents most serious outcomes and protects both mother and baby.

What are the warning signs that my UTI needs immediate medical attention?

Seek immediate help if you develop a high fever above 38°C, severe back or flank pain, persistent vomiting, or chills. These symptoms may indicate the infection has spread to your kidneys. Other red flags include blood in your urine, reduced foetal movement, or signs of preterm labour such as regular contractions. Confusion or difficulty staying alert also requires urgent evaluation, as these can signal sepsis.

Are antibiotics safe to take during early pregnancy for a UTI?

Yes, several antibiotics are safe during pregnancy and effectively treat UTIs. Your doctor will prescribe medications like amoxicillin, cephalexin, or nitrofurantoin, which have been extensively studied and shown to be safe for the developing baby. Some antibiotics, such as trimethoprim, should be avoided in the first trimester as they can increase miscarriage risk. Always inform your healthcare provider about your pregnancy before taking any medication.

How quickly should I see improvement after starting antibiotics for a UTI?

Most women notice symptom improvement within three to four days of starting antibiotics. Burning during urination typically decreases, and urine becomes clearer. Complete the entire prescribed course even if symptoms resolve early, as stopping treatment prematurely can allow bacteria to return. Your healthcare provider will likely schedule a follow-up urine test one to two weeks after finishing antibiotics to confirm the infection has cleared completely.

Can I prevent UTIs during pregnancy naturally without medication?

Whilst antibiotics are necessary to treat active infections, several natural strategies help prevent UTIs. Drink plenty of water throughout the day to flush bacteria from your urinary tract. Practise good hygiene by wiping from front to back and urinating after intercourse. Wear breathable cotton underwear and avoid scented intimate products. Cranberry juice may offer some protective benefits, though evidence is mixed. These preventive measures reduce infection risk but cannot replace medical treatment when infection develops.