Polysomnography is used to diagnose, or rule out, many types of sleep disorders including narcolepsy, idiopathic hypersomnia, periodic limb movement disorder (PLMD), REM behavior disorder, parasomnias, and sleep apnea.
Calculating Due Date: Estimated Due Date. Based on the last menstrual period, the estimated due date is 40 weeks from the first day of the period. This is just an estimate since only about 5% of babies are born on their estimated due date.
1 Last Menstrual Period: Using the first day of your last menstrual cycle, gestational age can be determined (plus or minus 2 weeks.) The doctor adds 280 days to the first day of your last menstrual cycle to determine a due date.2  Based on that number and todayâs date, gestational age is estimated. Last Menstrual Period: Using the first day of your last menstrual cycle, gestational age can be determined (plus or minus 2 weeks.) The doctor adds 280 days to the first day of your last menstrual cycle to determine a due date.