"This is the country's first case study," said Dr Adisorn Phattaradul, director of Chulalongkorn hospital which admitted the 24-year-old mother from Ratchaburi province on Saturday.
After the baby was born prematurely last Tuesday her mother developed a severe form of type-A (H1N1) influenza before being transferred to Chulalongkorn - the country's leading medical school - to receive special care.
She is now in a critical condition with severe pneumonia. Doctors say the virus has spread to her lungs and she is on a respirator in the intensive care unit. They have given her the antiviral drug oseltamivir and sleeping pills to help her recovery.
Meanwhile, her newborn daughter is in a baby incubator and has also been given antiviral drugs. Doctors say her lungs are now normal but they are worried the virus might affect her brain.
Dr Lelanee Paitoonpong, an infectious disease specialist of Chulalongkorn University said:
"Mother to child transmission of type-A (H1N1)flu in this case was only an assumption."
She said to reduce the risk of getting a severe form of flu-like illness, pregnant women should avoid close contact with people with symptoms and keep clear of public spaces.They should also wear face masks to prevent infection, she added.
To date, Thailand has 6,776 reported cases of type-A (H1N1) influenza which has killed 44 victims nationwide.
Prime Minister Abhisit Vejjajiva has assured the public adequate stockpiles of antiviral drugs and vaccine are on hand.
He said the Public Health Ministry is now improving its methods to help patients with flu-like symptoms to access treatment faster.
Deputy Public Health Minister, Manit Nopamornbodi said the ministry will today send 980,000 health care volunteers to screen patients for severe forms of type-A (H1N1) symptoms in villages and communities to reduce cases of infection and death. -The Nation/ANN