Mumps in Pregnancy

Seen mostly as a mild disease of childhood, mumps is caused by a paramyxovirus and is highly contagious. It spreads relatively quickly via the respiratory route (e.g. sneezing and coughing) and through skin-to-mucosal contact with contaminated material.

Mumps has an incubation period that ranges from 12 – 25 days.  While the earlier part of this period is not infectious, mumps-affected people become contagious a few days before the onset of the signs and symptoms. Furthermore, they remain so for a few days after the disease becomes apparent.

Classically, mumps manifests with the painful swelling of the parotid salivary glands, which is referred to medically as parotitis. Up to as many as 30% of unvaccinated patients, more commonly adults, may not experience any symptoms.

However, complications of mumps include inflammation of the testicles and ovaries as well as breast tissue and the pancreas.

Serious adverse effects such as hearing loss, aseptic meningitis and encephalitis may also be seen, although the latter is rare.

Headaches, malaise, myalgia, high fever, and anorexia are nonspecific symptoms that may occur.

Fetal Consequences

Mumps during pregnancy may be understandably more worrying than when it occurs in the general population. This statement is especially true considering the results from a study done in the late 1960s, before the MMR vaccine was introduced.

The study reported an increased risk of death to the developing embryo and fetus in addition to spontaneous abortion during the first trimester of gestation.

In another study, congenital malformations were linked to mumps infection during pregnancy. However, the CDC notes that this study had methodological flaws, because the investigator failed to make a comparison between rates of infants who were born to affected and unaffected mothers.

Additionally, other studies failed to find any correlation between mumps and congenital malformations. Thus, overall the evidence of increased fetal loss to mumps during pregnancy is weak and there is none to really support severe congenital abnormalities.

A study was done on 5 women in their second trimester who were immunized with an attenuated strain of the mumps virus 7 – 10 days before their scheduled therapeutic abortions.

In 2 of these women, mumps was detected in the placenta, but it was not found in any of the fetuses. It was acknowledged that it is possible that viral replication in the organs of the fetus did not occur owing to short interval between abortion and immunization.

Perinatal investigations were done on 3 women who had symptomatic mumps during the birth of their babies. One baby had parotitis and a positive mumps test 42 days later.

The second baby developed pneumonia a week after birth and had respiratory complications during his first 12 months of life. However, they both went on to have normal growth and development.

The third baby was healthy and never developed any signs, symptoms or complications associated with mumps.

Maternal Consequences and Treatment

Aside from the classical presentation of the disease and associated effects, there is no evidence that pregnant women are at an increased risk of developing more severe complications compared to the general population.

On the basis of this knowledge, there is no specific treatment offered to pregnant women who contract the disease other than the usual supportive therapy. This includes increasing fluid intake, and medication to reduce pain and fever.

There is also no currently available therapy to reduce risks to the fetus in mothers infected with mumps.

Such therapy might not be necessary either considering the weak evidence for serious effects to the fetus, or fetal loss.  

Further Reading

• All Mumps Content
• What are Mumps?
• Mumps Prognosis

Written by

Dr. Damien Jonas Wilson

Dr. Damien Jonas Wilson is a medical doctor from St. Martin in the Carribean. He was awarded his Medical Degree (MD) from the University of Zagreb Teaching Hospital. His training in general medicine and surgery compliments his degree in biomolecular engineering (BASc.Eng.) from Utrecht, the Netherlands. During this degree, he completed a dissertation in the field of oncology at the Harvard Medical School/ Massachusetts General Hospital. Dr. Wilson currently works in the UK as a medical practitioner.