You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is The earliest immunoglobulin to be synthesized by the fetus is: and explain in detail?
IgM is the earliest immunoglobulin to be synthesized by the fetus, beginning at about 20 weeks of age IgM holds special significance as it does not cross the placenta. It's presence in the fetus or neonate therefore indicates intrauterine infection and its detection is useful in the diagnosis of congenital infections. IgM antibodies are relatively sho lived disappearing earlier than IgG. Its demonstration in the serum therefore indicates recent infection. Ref: Textbook of Microbiology By Ananthanarayan and Panicker, 6th Edition, Page 83 ; Immunology: A Sho Course By Richard Coico, Geoffrey Sunshine, 2009, Page 53