Prenatal infections are infections that can be passed from mother to baby in the womb.
In this country prenatal infections are not particularly common but they can include tuberculosis (TB), cytomegalovirus (CMV), group B streptococcus (group B Strep), parvovirus and listeria.
Group B strep is the most common cause of life-threatening infection in newborn babies in the UK, however some parents-to-be may not have heard of the disease.
Dr Penelope Law, Consultant Obstetrician and Gynaecologist, answers some of the most commonly asked questions in honour of Prenatal Infection Prevention Month.
What does prenatal infection mean?
Prenatal infection refers to any infection that is present or acquired during the pregnancy and can be passed from the mother to the baby. Pregnant women may be more susceptible to infection because their immune system is slightly less reactive to prevent the rejection of the foetus.
How are they contracted?
TB is present in all countries of the world. It is treatable but it can be more serious in pregnancy and is spread by droplets in the air – person to person.
CMV is a respiratory virus, which most UK women have been exposed to before pregnancy but if first encountered during pregnancy it can cause major problems for the baby. It is not currently tested for routinely in pregnancy in the UK.
Group B strep is a common bacteria which is found in about 20% of women among the normal vaginal bacteria. It is usually not a problem but if not detected can lead to transmission to the baby particularly if the amniotic fluid has been draining for 24 hours or more. For this reason women are offered antibiotics in labour if their waters have been broken for more than 24 hours and they have not yet delivered.
Parvovirus is a virus also referred to as 'slapped cheek”. It mainly affects young children and can lead to complications in the foetus if the mother first meets it in pregnancy.
Listeria is a relatively common bacteria found in unpasteurised milk and cheese, and also some unprepared salads. Again it is actually rare for this to complicate pregnancies if those foods are avoided but it can sometimes lead to premature birth or miscarriage.
How can these infections be treated?
Most can be treated in pregnancy – including TB – there can be complications for the foetus if treatment is delayed.
There is no good treatment for CMV, only supportive treatment for the foetus if complications develop.
Again with parvovirus, supportive measures and regular growth scans are offered.
Listeria can be treated with antibiotics in the mother; however, sadly it is usually discovered after the event of miscarriage or premature birth.
How can you prevent prenatal infections?
The short answer is that we cannot totally prevent any infections but we can make sure that our immune system is as effective as it can be by eating the right things and sleeping well.
For instance, listeria is generally more commonly found in earth and food stuffs – so avoiding contact with cat and dog excrement is preferable when pregnant (and public sandpits are not such a good idea with toddlers if you are pregnant). Group B strep is found incidentally in 20% of the female population, so for some it is impossible to avoid – there is testing available but you will be treated as if you have it during the most risky time – i.e. when your waters have been broken for more than 24 hours and your baby is not yet delivered. Ensuring that you do take the suggested antenatal immunisations is also advisable, and early attendance to your GP with symptoms of a urine infection or abnormal vaginal discharge is important. Just remember that the majority of women do not have serious antenatal infections, and if they do only a small proportion of them result in a poor outcome for the mother or baby.
What tests should I ask my GP or midwife for to check for prenatal infections?
Your midwife or obstetrician will check for exposure to several infections when you are first pregnant including Rubella, which is now rare. CMV and toxoplasmosis is not routinely checked for although if you feel you would be at risk, then tests can be done. Group B strep is not routinely checked for.
What tests do we offer at The Portland for prevention / diagnosis of prenatal infections?
At the Portland we can offer testing – usually around 37 weeks of pregnancy for group B strep, also for toxoplasmosis, CMV, and hepatitis B and C.