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.
Alternately, remember Naegele's Rule. An easier way in figuring out due dates is to take the first day of your last period, count backward 3 months, add 7 days, and add an entire year. This is called Naegele's Rule. (Alternatively, to get the same result, you can take your LMP, add 1 week, and add 9 months.)