Babies are surrounded by amniotic fluid as they grow and develop in the womb. This fluid enables them to move freely and is essential for normal growth and development in utero.
The amniotic fluid acts as a protective cushion around your baby to prevent injury from bumps to the abdomen. It also plays a vital role in developing immunity and maintaining a constant temperature.
Sometimes, however, an infection can develop within the amniotic fluid, causing potentially serious complications in pregnancy for both mother and baby.
What is amniotic fluid infection?
An infection in the amniotic fluid can be referred to in a number of different ways including: clinical chorioamnionitis; intra-amniotic infection; and intrauterine infection.
In simple terms, they all effectively mean the same thing: a bacterial infection and acute inflammation of the tissues around the baby. This can include a placental infection, infection of the fetal membranes (chorion and amnion), the umbilical cord, and/or the amniotic fluid.
Related reading: What Is The Amnion? | All You Need To Know
What causes infection in the amniotic fluid?
Chorioamnionitis is usually caused by bacteria or genital tract pathogens (organisms that cause disease), which are present in the mother’s body and travel up towards the baby.
Bacteria present in the vagina can migrate through the cervix and into the uterus, causing infection surrounding the baby. This is also known as an ascending bacterial infection.
Common types of bacteria and infections that can cause chorioamnionitis are:
- Group B Streptococci (GBS)
- Bacterial vaginosis
Can urinary tract infections cause intrauterine infection?
A urinary tract infection, or UTI, can lead to chorioamnionitis if left untreated.
It’s common for pregnant women to experience asymptomatic urinary tract infections, meaning they have a bacterial infection without being aware of it, or experiencing any symptoms.
This is one of the reasons why your care provider will ask you for a urine sample at each of your routine appointments, to screen for signs of an infection.
An untreated UTI is a common cause for Preterm Birth, so it’s always worth getting checked over by your doctor or midwife if you suspect you might have a water infection.
Who is at risk of chorioamnionitis?
There’s a number of risk factors that make the chances of developing an infection even more likely.
It is possible for anyone to develop an intra-amniotic infection during pregnancy, but it’s more common after the waters around baby have gone. The amniotic sac containing the waters provides a protective sterile bubble around your baby, but once the waters are broken, this leaves potential for bacteria from the lower genital tract to enter, causing possible fetal complications.
Prolonged Rupture Of Membranes is of clinical significance as the chances of developing an intra-amniotic fluid infection increase the longer the time between the waters breaking and your baby being born.
Babies born following premature or prolonged rupture of membranes are at increased risk of neonatal sepsis and neonatal complications.
An infection can still occur at full term, however – even in the presence of intact membranes.
Other clinical risk factors are:
- First pregnancies
- Tobacco or alcohol use
- Frequent vaginal examinations (VE)
- Sexually transmitted infection
- Vaginal or urinary tract infection
- Prolonged labor
- Internal fetal monitoring in labor
- Epidural anesthesia
- Group beta streptococcus (GBS)
- Preterm birth
- Meconium In Amniotic Fluid.
Related reading: How To Get Through Transition Without An Epidural | All You Need To Know.
Chorioamnionitis – signs and symptoms
You might be wondering how to know whether you have an infection.
Usually, maternal diagnosis of clinical chorioamnionitis is based on the mother’s clinical findings alone.
Here is a list of clinical signs you might experience with chorioamnionitis:
- Isolated maternal fever associated with a raised white blood cell count
- Maternal or fetal tachycardia (raised maternal pulse or a raised fetal heart rate)
- Uterine tenderness
- Premature rupture of membranes
- Meconium stained amniotic fluid
- Preterm labor symptoms or Preterm Birth
- Foul smelling or green/yellow discharge.
Although any of the above symptoms can point towards intra-amniotic infection, it is important to remember that some women will not experience any symptoms at all. This is known as a subclinical infection.
How is chorioamnionitis diagnosed?
Although an intrauterine infection is most commonly diagnosed by physical examination and discussion of symptoms, diagnosis is also possible by amniocentesis, although this is not performed routinely.
An amniocentesis is usually used as part of the prenatal screening process, to test for certain genetic disorders, such as Down syndrome, or neural tube defects, such as spina bifida. The prenatal test involves taking a sample of amniotic fluid by passing a special needle through the abdomen to collect the sample.
If an intra-amniotic infection is suspected, an amniotic fluid culture can be taken to screen for infection.
Other methods of diagnosis more commonly used to detect chorioamnionitis involve blood tests or vaginal swabs.
How common is intra-amniotic infection?
Chorioamnionitis is not very common but it’s a leading cause of premature labor and preterm birth.
Intraamniotic infection occurs in 1-4% of full-term births (over 37 weeks) in the US.
It’s more common in preterm births, affecting 40-70% of births under 37 weeks gestational age.
What are the risks of chorioamnionitis?
Chorioamnionitis is a potentially dangerous infection that can cause complications in pregnancy and after birth for both mother and baby.
Complications for the mother
If the mother has a particularly bad case, or if the infection goes untreated, she might develop complications including:
- Pelvic infections
- Endometritis (an infection of the lining of the uterus)
- Blood clots in the pelvis or lungs
- Maternal sepsis (a life-threatening infection affecting major organs and tissues)
- Wound infections. Of those who have a cesarean birth, up to 8% will develop a wound infection and approximately 1% will develop a pelvic abscess
- Postpartum hemorrhage (heavy bleeding after birth)
- Preterm labor and birth
Complications for the baby
- Premature birth and associated complications of preterm infants
- Low birth weight infants
- Breathing problems or chronic lung disease
- Retinopathy of prematurity (ROP) – an eye disorder affecting premature infants
- Early onset neonatal sepsis or neonatal infection
- Neonatal pneumonia or meningitis
- Cerebral palsy and other neurodevelopmental disabilities
- Neonatal death.
How is chorioamnionitis treated?
The treatment for chorioamnionitis depends on the severity of the infection and how well both the mother and baby are. Sometimes it is necessary for the baby to be born as soon as possible to prevent further complications.
Chorioamnionitis alone is rarely a reason for cesarean delivery but induction or augmentation of labor might be advised. Augmentation of labor involves speeding up the process of labor, either by breaking the waters (artificially) or using a hormone drip to speed labor up.
Regardless of the mode of birth, intrapartum antibiotic treatment for the mother will be advised; intravenous antibiotic therapy will also be required for the baby, to prevent an infection from developing.
Can a baby be born with an infection?
A baby can be born with an infection, which is why it’s important not only to treat the mother, but also to offer the baby immediate postpartum treatment following birth, to prevent further complications.
Your baby will probably need to stay on the neonatal baby unit for extra observations and might require postpartum antibiotics and blood cultures.
This will not affect your ability to breastfeed if you’re planning to. Your health care team can support you to do this while your baby is in the baby unit.
If your baby is too poorly to breastfeed, your health care team can help you to express, so that your breast milk can still be given to your baby.
Breastfeeding or using expressed breast milk is especially important if your baby develops an infection, as breast milk contains antibodies and stem cells that can help fight infection and promote healing.
How to prevent a intrauterine infection
There are some things you can do to try to prevent an intrauterine infection:
- Avoid tobacco, alcohol, and drug use
- Get tested if you suspect you have a vaginal infection or sexually transmitted infection
- Attend all of your prenatal appointments with your care provider
- Report any signs of a urinary tract infection
- Limit vaginal examinations in labor, if possible.
If your waters break early
If your waters break early (before 37 weeks), this is known as prelabor premature rupture of membranes (PPROM). Your care provider is likely to advise oral antibiotic treatment or intravenous antibiotics to reduce the chances of the infection being transferred to baby in the womb.
Prompt administration of antibiotic therapy is essential to prevent maternal and fetal complications associated with chorioamnionitis. Antibiotics and other medications can also be used to prolong the time between your waters breaking and birth; this will give your baby as much time as possible to continue developing in the womb, so as to reduce complications associated with premature birth.
Related reading: Antibiotics During Labor – Risks And Benefits.
Can chorioamnionitis affect future pregnancies or cause infertility?
If you have been previously diagnosed with chorioamnionitis, it can affect your chances of developing it again in a subsequent pregnancy; the chances, however, remain low.
If Group B strep was diagnosed previously, you will probably be offered a Group B Strep Test or routine treatment for GBS in a future pregnancy.
If your baby was born prematurely, due to chorioamnionitis, you will be monitored closely in a future pregnancy for any signs of Preterm Labor symptoms.
When should I call my healthcare provider?
If you’re feeling unwell in your pregnancy, or have signs such as maternal fever or maternal tachycardia (raised heart rate), you should contact your midwife or doctor right away.
If you believe your waters have broken before 37 weeks, or if they have a foul (malodorous) smell, seek professional medical advice as soon as possible.
These can be signs of an intrauterine infection. Early treatment can prevent complications or an adverse outcome, such as premature birth and neonatal sepsis.