Chickenpox to the fetus. Varicella infection in pregnant women could lead to spread via the placenta and infection of the fetus. If infection occurs during the first 28 weeks of gestation, this can lead to fetal varicella syndrome (also known as "congenital varicella syndrome"). Effects on the fetus can range in severity from underdeveloped toes and fingers to severe anal and bladder malformation. Possible problems include: Infection late in gestation or immediately following birth is referred to as ""neonatal varicella"". Maternal infection is associated with premature delivery. The risk of the baby developing the disease is greatest following exposure to infection
Rare disease treated, are excluded from their definition. The definitions used in the medical literature and by national health plans are similarly divided, with definitions ranging from 1/1,000 to 1/200,000. Because of definitions that include reference to treatment availability, a lack of resources, and severity of the disease, the term "orphan disease" is used as a synonym for "rare disease". But in the United States and the European Union, "orphan diseases" have a distinct legal meaning. The United States' Orphan Drug Act includes both rare diseases and any non-rare diseases "for which there is no reasonable expectation that the cost of developing