Preventive principles
The first reflex to adopt in a pregnant woman or woman wanting to become pregnant is to assess her immune status: for those who are not vaccinated, “ just ask women, because many studies prove that memory is reliable,” insisted Professor Olivier Picone (Louis-Mourier Hospital, Colombes). “Those who say they have had chickenpox are rarely wrong. » Serology is more readily considered for those who say they have not been infected, because they are seropositive in 90% of cases, even if women from Asia or Africa are less frequently (between 60 and 80%). Vaccination – using a live attenuated vaccine – is contraindicated during pregnancy and requires compliance with a minima one month before starting a pregnancy. But it remains one of the pillars of prevention for all women of childbearing age. This vaccine does not protect 100% but reduces the risk of serious forms by 95%.
Prevention in the event of chickenpox infection during pregnancy requires estimating the length of contact, knowing that contagiousness precedes the rash by two days. When the infection is less than 14 days old, serology must be requested “urgently” and within 10 days post-infection in order to know whether IgVZV should be administered. “ This new deadline allows sufficient time to carry out the serology and administer the treatment, which was not possible with the previous deadline of 3 days,” explained the specialist. “A study shows that for those who receive IgVZV, the risk of chickenpox is halved. » Between 10 and 14 days of infection, oral valaciclovir is preferred (1 g three times a day for 7 days).
The risk of neonatal chickenpox, which can cause serious complications, is greatest when the first signs of chickenpox appear in the mother during the 7 days preceding delivery or the 7 days following it, because the mother will not have had the time to develop or transfer in utero enough antibodies, while the newborn’s immune system is immature. “ Before delivery, this justifies induction, while after delivery, pediatricians and/or neonatologists should be warned of the risk of neonatal varicella. »
A gradation of risk depending on the term of pregnancy
The main risk for pregnant women is, as for other adults, chickenpox pneumonia: it affects 10 to 20% of infected subjects, but respiratory damage is more severe in pregnant women than in others. Up to 1/3 of them, especially those who smoke and those who are on 3e trimester of pregnancy, will have to be admitted to intensive care.
Regarding the fetus, infection doubles the risk of prematurity. Several other complications affect his prognosis:
- Before 20 weeks of amenorrhea (AS), there is a risk of serious congenital varicella syndrome (CVS, malformative risk with multivisceral and metameric involvement) in 1 to 2% of cases. However, even if the newborn is born asymptomatic, there is a risk of postnatal shingles up to the age of 2 years.
- From 3 weeks before birth to 7 days after, there is a risk of acquired neonatal varicella. in utero. It can be serious, with diffuse mucocutaneous, potentially necrotic and visceral damage. It generally occurs before D10 of life but can take until the 21st.e day, especially if the mother received IgVZV.
- Finally, the risk of postnatal chickenpox occurs in the newborn after infection after birth through the air or skin. It generally begins after the 10the day of life and is associated with an 8-fold increased mortality rate compared to chickenpox occurring between the ages of 1 and 4 years.
Diagnosis of chickenpox during pregnancy is clinical, except in special cases, and management is no different from that of other adults (valaciclovir and hospitalization in a single room in the event of pneumonia). However, women who have had chickenpox before 20 weeks of gestation should be informed about the risk of CVS, which can be detected by ultrasound.
In symptomatic newborns after an infection occurring less than 3 weeks before birth and up to 7 days afterwards, a VZV PCR can be performed. Antiviral treatment is based on IV aciclovir, with isolation in a single room, precautions regarding contacts, without the need for separation between mother and child. Breastfeeding is not contraindicated. In asymptomatic children, monitoring must be maintained for 28 days.
