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Congenital infections were one of the two areas of congenital anomaly that were the focus of the 2016 report. The decision to focus on this area pre-dated the publicity generated by Zika virus and associated microcephaly in south America. No cases of Zika-associated microcephaly have yet been notified to the CARIS database, however enhanced surveillance has been commenced in maternity units across the UK.

For more information on the surveillance please see the UKOSS website here.

For more information on Zika virus please see the NHS Wales health website here.

133 cases of congenital infection were recorded on the CARIS database between 1998 and 2015. The infections that could have been reported include congenital syphilis, congenital viral diseases including rubella, herpes, varicella (chickenpox) and cytomegalovirus, and toxoplasmosis. However not all the infections listed were found on the database, for example there were no cases of congenital rubella recorded.  

In 2016 Public Health Wales updated the guidance on 'Rash in Pregnancy'.

Historically CARIS has recorded all cases of congenital infection reported to the database team, whether or not a congenital anomaly was detected at birth. This has resulted in a number of records being held, where it is not clear that any anomaly exists. There are plans to review the CARIS data definitions in 2016/17 and this is one of the areas that will be reviewed.

Cytomegalovirus (CMV)

What is it?

This is a relatively common virus that belongs to the herpes family of viruses. It is spread through bodily fluids such as blood, saliva, semen, urine and vaginal fluids. The virus can present as a ‘flu like illness or there may be no symptoms at all. The virus also has the characteristic of being able to remain in the body without detection over long periods of time, and in healthy people may go unnoticed.  If a pregnant woman has either a new infection or reactivation of an existing infection, the virus can pass to the developing baby.

How is it detected?

If the mother has an active infection, this can be picked up with a blood test for immunoglobulins. The effects on the fetus can be detected on ultrasound scan if the effects are significant, and the presence of CMV can be confirmed by testing amniotic fluid following amniocentesis. The virus can be detected in urine and saliva in the newborn baby.

What are the effects on the fetus?

If a mother becomes infected for the first time in the first half of pregnancy the risk of transplacental infection is about 40%. Of these babies,  between 5 and 15% are affected at birth. Effects may include hepatosplenomegaly, thrombocytopaenia, intracranial calcifications, intrauterine growth restriction, jaundice, microcephaly, chorioretinitis, hearing loss, learning difficulties and fits. Of those affected, up to 30% may die, while 80% of the survivors will have ongoing serious health problems.

If the maternal CMV infection occurs later in pregnancy there is a much higher risk of transplacental transmission but the risk to the baby is much less. One of the common anomalies associated with CMV infection is sensorineural hearing loss and for this reason many of the cases reported to CARIS are detected by the newborn hearing screening programme. Later problems can present in children as neurologic, auditory, visual and dental defects. If the mother has a recurrent or reactivated infection, there is a significantly reduced risk of fetal problems.

How common is cytomegalovirus in Wales?

It is estimated that between one and two babies in every 200 will be born with congenital CMV. Of these about 13% will have congenital anomalies relating to the infection.  54 cases were reported to CARIS between 1998 and 2015. 78% of these were known to have a congenital anomaly, predominantly sensorineural hearing loss. Given what is known about international prevalence, the figure of 54 is probably under reported, as we could expect more than 300 affected cases with anomalies since 1998. Many of the children will be mildly affected with minor visual or auditory problems which may only become apparent when they are in school and this could be a reason why they are never reported to CARIS.

More information


What is it?

This is a disease caused by the parasite Toxoplasma gondii. The parasite is found in cat faeces and in infected meat and has to be ingested to cause infection, it cannot be spread through person-to-person transmission. It can live in soil or water for a long time, so can be spread to people in contact with infected soil i.e. through gardening.  It can also be spread from mother to fetus during pregnancy.

 Infections in humans usually cause no symptoms, or simply a mild flu like illness. However the infection can be more serious in people who are immunocompromised such as those on long-term steroids or the very young, and acute toxoplasmosis in pregnant women can have serious consequences for the fetus.

What are the effects on the fetus and baby?

It is thought that acute toxoplasmosis in the mother can result in a 30% chance of placental and fetal infection. The chance of fetal infection increases with gestational age.  The outcomes can be serious and include fetal death and miscarriage. The baby may have neurological problems, learning difficulties and chorioretinitis of the eyes. Treatment of the mother with antibiotics may help reduce placental transmission and deleterious effects on the baby. Pregnant women are also offered advice on avoiding eating under-cooked meat, and to take good hygiene precautions when handling cats or cleaning litter trays. This is to prevent them becoming infected during pregnancy. 

How common is congenital toxoplasmosis in Wales?

An estimated third of people in the UK will be infected by toxoplasmosis some time during their lives, however the majority will not be aware of this as they will not experience any symptoms. When pregnant women are affected there is a risk that the fetus may be affected – the pregnancy could result in miscarriage, stillbirth or be affected by congenital anomaly. If a woman develops acute toxoplasmosis during pregnancy, the risk of the infection reaching the placenta is about  30%.

10 cases of congenital anomaly caused by toxoplasmosis were reported to the CARIS database between 1998 and 2015. All of these had a confirmed anomaly.

More information


What is it?

Parvovirus B19 is a very common infection which affects humans, and usually causes a mild cold-like illness or no symptoms at all. It affects more children than adults, and is also known as slapped cheek or fifth disease. People affected usually have a mild illness with a rash, and in children the rash is most noticeable on their cheeks which can become very red. It is spread through respiratory infections but can also be spread through blood or blood products. Parvovirus can be more serious in people with a weakened immune system. It can be passed to the fetus if the mother is infected in pregnancy and is not already immune to the virus.

What are the effects on the fetus and baby?

Transplacental transmission occurs in about 25% of susceptible affected women with an average of 6 weeks between maternal infection and it developing signs in the fetus. Fetal loss rate, following infection, is estimated at 5-10% and the fetus is most vulnerable during the second trimester –  13 to 16 weeks gestation is the most critical stage at which health problems are likely to occur.

Fetal infection affects the bone marrow’s production of red blood cells and results in anaemia. It can also cause myocarditis. Severe heart problems or anaemia can cause heart failure and resultant fetal hydrops. Parvovirus B19 is the most common cause of non-immune fetal hydrops. Sometimes the problems resolve and there are no problems at birth, but occasionally the condition can lead to fetal death.

How common is parvovirus in Wales?

26 cases of congenital anomalies due to parvovirus have been recorded on the CARIS database between 1998 and 2015. While parvovirus is a common infection, according to Orphanet the worldwide prevalence of fetal parvovirus is unknown.

More information

More information for investigation and management in pregnant women

Varicella Infection (chickenpox)

What is it?

Varicella-zoster virus (VZV) is a DNA virus which is quite common and causes chickenpox. VZV can persist in the body after an initial infection as a latent infection and reactivation of latent VZV causes shingles. VZV is spread through respiratory infection and through the conjunctiva. While an effective vaccine against chickenpox is available, it is not part of the routine childhood immunisation schedule in the UK, but is advised for certain groups seen as being at higher risk of complications.

More information about the chickenpox vaccine and who should receive it can be found here.

What are the effects on the fetus and baby?

Maternal infection during the first 28 weeks of pregnancy can lead to intrauterine infection in about a quarter of cases but in only a very small proportion of these will result in congenital varicella syndrome in the fetus. The risk varies between 0.4% and 2% with increasing gestation. The syndrome can comprise low birth weight and severe multisystem involvement. This includes neurological abnormalities, eye lesions, skeletal anomalies, skin scarring and limb hypoplasia.  An amniocentesis can be done to confirm infection but this test can be unreliable and carries the risk of miscarriage.

Infections later in pregnancy can cause infant shingles, neonatal chickenpox or the serious purpura fulminans (disseminated haemorrhagic neonatal chicken pox) which can be fatal. These sequelae are determined by the gestation at the time of maternal infection.

According to CDC “The onset of maternal varicella from 5 days before to 2 days after delivery may result in overwhelming infection of the neonate and a fatality rate as high as 30%. This severe disease is believed to result from fetal exposure to varicella virus without the benefit of passive maternal antibody.”

Pregnant women themselves are at higher risk of complications from varicella, as a small percentage go on to develop an associated pneumonia which can be serious.

The Royal College of Obstetricians and Gynaecologists has issued evidence-based guidance on the management and follow-up of women who contract chickenpox during pregnancy:

What is the prevalence in Wales and elsewhere?

Ascertainment of the correct number of pregnancies adversely affected by VZV is challenging. There were 38 cases recorded on the CARIS database between 1998 and 2015, however these may have been women who were notified to the CARIS team as they had contracted chickenpox during pregnancy, but there may not be an associated congenital anomaly present. International prevalence is unknown.

More information

Management during pregnancy:!scenario:1  (this is a site from the USA so any links to information about vaccination will not be relevant)

Rubella (German Measles)

What is it?

Rubella virus is a togavirus, transmitted by respiratory secretions. It is a notifiable disease that causes symptoms that are similar to flu except that the primary symptom is a rash. In about half of cases the infection may be sub-clinical.  Immunisation against rubella is part of the core childhood immunisation programme in the UK, and rubella vaccine is combined with mumps and measles vaccine to form the MMR vaccine. Women thinking of becoming pregnant should ensure they have had two doses of MMR prior to becoming pregnant. Rubella is usually a mild illness but can have serious consequences for the fetus if contracted during pregnancy.

What are the effects on the pregnancy and baby?

These are serious as the virus can cross the placenta and infect the fetus, and congenital infection can affect all organ systems of the body. It has teratogenic properties that affect the developing cells and can cause Congenital Rubella Syndrome (CRS). The syndrome consists of cardiac, cerebral, opthalmic and auditory defects. It may also cause  prematurity, low birth weight, neonatal thrombocytopenia, anaemia and hepatitis. Some of the effects of CRS such as hearing loss or eye problems may not become apparent until a child is aged two or older.

The risk of major developmental anomalies is highest when infection occurs in the first trimester – the risk is estimated by the USA Centers for Disease Control (CDC) at about 85%. Fetal infection can occur throughout the pregnancy but the complications are less severe the later in pregnancy the infection occurs, and are rare after about 20 weeks gestation.

Antenatal screening for rubella stopped in the UK in 2016. More information about why that decision was taken can be found here.

What is the prevalence  and rates in Wales?

There were 12 cases of congenital rubella reported in the UK between 2005 and 2015, but none of these could have been prevented by the screening programme as they were in women born overseas. There have been no cases of congenital rubella in Wales in the last 10 years and none have been recorded on the CARIS database since 1998.

More information (this is a site from the USA so any links to information about vaccination will not be relevant)

[1] Fetal hydrops is a serious condition for the fetus or newborn baby, in which abnormal amounts of fluid build up in areas of the body such as the skin, abdomen, pericardium or pleura.