A new study shows that nine hours of sleep is the right amount for pregnant women, especially in their first trimester. The study polled 1,200 pregnant women on how much they slept per night. Here are the results: 20.5% slept 9 hours. 55.2% slept 7-8 hours. 13.7% slept 6 or less hours per night. 10.6% slept 10 or more hours per night. Too little pregnancy sleep. As shown by the study, most pregnant women are not getting enough sleep.