A close encounter with CMV infection during pregnancy

She was distraught when her blood tests confirmed that she had been infected with CMV- the cytomegalovirus. K, a 28-year-old kindergarten teacher and a first-time mum was at her 18 weeks of pregnancy. She had a mild fever and sore throat about 2 weeks ago. There were some swollen lymph nodes on her neck.

“Doc, will CMV affect my baby?” She asked.” I read in the internet that it can cause blindness, hearing loss and mental retardation in my child.” I told her that she had about a 40 % chance of transmitting CMV to the baby. Of the babies that become infected, only 10% will show signs of congenital CMV with multiple disabilities.

Cytomegalovirus (CMV) is a very common virus that can infect almost everyone. The primary (first time) infection usually occurs in children and less often, in adults, as in K’s case. It is estimated that between 60 to 90 percent of all adults would have had the infection. It belongs to the same family of viruses that causes chickenpox and herpes. Once infected, the virus stays in the body for life. Most people do not know they have had CMV because it rarely causes symptoms. If symptoms do occur, they include sore throat, swollen tender lymph nodes, mild fever, fatigue and feeling unwell.

CMV is transmitted through infected bodily fluids such as blood, saliva, urine, semen and breast milk. Pregnant mothers can get the primary infection via sexual intercourse or through contact with children. CMV is the most common virus that passes from mothers to babies during pregnancy. About 1 to 4 in 100 women have CMV during pregnancy. Majority (85-95%) of the babies born with CMV do not have health issues. But in the remainder, serious birth defects can occur. They include:

  • Microcephaly, in which the baby’s head is smaller than normal. This may result in mental retardation.
  • Enlargement of the liver and spleen.
  • Problems with the vision and hearing.
  • Seizures.

In some babies who have no symptoms at birth, varying degrees of hearing, mental or coordination problems may develop later in life. Thus, long term follow-up of the baby is of utmost importance.

K asked me in what way she could find out whether her baby was affected with the virus. The only way, I said was by a procedure called amniocentesis in which a long needle is introduced into the uterus to withdraw some amniotic fluid which surrounds the baby. Virus could then be cultured from the fluid.

After prolonged discussion with her spouse and family, K decided to continue with the pregnancy without any intervention. A fetal anomaly scan at 20 weeks showed that the brain, heart and abdominal organs were normal. The pregnancy progressed smoothly and the baby’s brain MRI scan at 36 weeks gestation did not show any abnormality. K finally delivered a healthy baby boy at 39 weeks of gestation. She had a sigh of relief when the urine and blood of the baby were tested negative for CMV.

“What a close encounter with CMV!” she exclaimed.

Dr Chew is an experienced gynaecologist running his own women’s clinic practice here in Singapore. Read up on his general gynaecology services as well as his article on postpartum haemorrhage (PPH).

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