A 6-week-old girl was found dead Christmas morning after spending the night co-sleeping with her mother and her 2-year-old brother.The mother, Africa Shaw, 27, told investigators that her daughter's lips were blue and her body cold when Shaw woke about 8:30 a.m. Friday, according to a medical examiner's report. The cause of the child's death has not been determined.Shaw told investigators she fed the child, Navaeh McIntosh, Thursday evening, and then placed the infant on a baby blanket on Shaw's queen-size bed. She covered the baby with a loosely knit baby blanket. Shaw slept with two pillows and a sheet. Her 2-year-old son, who slept at the foot of the bed, was covered with a blanket, according to a medical examiner's report.