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.
(Women are traditionally told their due date is 280 days, or 40 weeks, after the first day of their last period -- a rule of thumb that assumes each woman has a typical 28-day cycle and that each woman ovulates on the 14th day of her cycle.)