Sleep assessment
Sleep quality and BP were assessed at 4 visits: 9 to 14 weeks of
gestation (visit 1), 18 to 22 weeks of gestation (visit 2), 28 to 32
weeks of gestation (visit 3) and 34 to 39 weeks of gestation (visit 4).
During each visit, sleep quality was assessed via the Pittsburgh Sleep
Quality Index (PSQI) questionnaire. Four main questions were asked in
the questionnaire: (1) “During the past month, what time have you
usually gone to bed at night”; (2) During the past month, how long (in
minutes) has it usually taken you to fall asleep each night”; (3)
During the past month, what time have you usually got up in the
morning”; (4) During the past month, how many hours of actual sleep did
you get at night, which may be different from the number of hours you
spent in bed”. PSQI score was calculated after combining the scores for
each question. Women with poorer sleep quality have higher PSQI scores.
Furthermore, specific aspects of sleep quality including sleep latency
(question 2), sleep duration (question 4) and sleep efficiency
(calculated by actual hours of sleep over total hours from time in bed
to time of getting up) were also individually assessed and compared in
relation to blood pressure.