Pregnancy is characterized by important changes in sleep and some of them (as insomnia) predict negative outcomes, like depression, through all the perinatal period. There are few Portuguese adapted and validated instruments assessing insomnia in pregnancy.

To validate the Insomnia Assessment Scale in a sample of Portuguese pregnant women.

419 pregnant women (mean age: 32.51±4.759; weeks of gestation: 17.32±4.803) answered the Insomnia Assessment Scale (IAS), constructed according to the DSM-V and the ICSD-3 criteria and presenting fourteen items: three evaluating insomnia symptoms (1 to 3); one assessing if sleep difficulties were present although there were adequate conditions to sleep (item 4); one assessing if sleep difficulties occurred three times/week (item 5); one evaluating if sleep was not restorative (item 6); three assessing daily impairment associated to insomnia symptoms (7 to 9); two assessing the use of prescribed and/or homemade medication (10 and 11); three excluding that sleep difficulties were not due to another sleep disorder, substance use, a physical condition or a mental disorder) (12 to 14).

The IAS Kuder-Richardson alpha was very good (α=0.85) and none of the items increased the alpha if removed. A principal component analysis revealed a three factors solution, explaining a variance/EV of 63,74%: F1/Insomnia symptoms (items 1 to 6) (EV 36.02%; α=0.81); F2/Daily impairment associated to insomnia symptoms (items 7 to 9) (EV 18.67%; α=0.79); F3/Differential diagnosis (items 12 to 14) (EV 8.38%; α=0.81).

The IAS adapted for Portuguese pregnant women presented good reliability and validity.