RESULTS
As shown in Table 1a, our study subjects consist of a multiracial
population with average age of 30 years and different educational
levels, occupations and social status. Chinese and Malay women made up
most of our study subjects (50.7% and 27.3% respectively) with small
numbers of Indians and others. Most of the subjects have education
levels of high school/junior college and above. Their household income
ranges from <3500 to more than 8500 Singapore dollars a month,
with most women working as white-collar workers. Similar percentage of
nulliparous (54.4%) and multiparous (45.6%) women were included in
this study.
Life style, BMI, blood pressure and sleep quality throughout pregnancy
were presented in Table 1b. A small percentage of women continued to
drink coffee during pregnancy (21-33.4%). A smaller percentage of women
remained actively drinking (0.8-2.5%) or smoking (1.8-2.6%) during
pregnancy. Average BMI of the patients increased expectedly throughout
pregnancy (from 24.1 at the first visit to 28.1 at the last visit). The
average SBP/DBP (MAP) in the 4 visits were 108/66 (80) mmHg, 109/65 (79)
mmHg, 110/66 (81) mmHg and 112/69 (83) mmHg respectively, showing an
overall upward trend. Sleep quality score, as represented by PSQI, had
an average range of 6.3-8. The average of individual aspects of sleep
quality including sleep duration (6.5-7.0 hours), latency (20-26mins)
and efficiency (82-85%) were also shown in Table 2. Overall sleep
quality, sleep efficiency and latency worsen while sleep duration
shortens as pregnancy progresses.
During the first visit, it was found that SBP (p=0.019), DBP (p=0.023)
and MAP (p=0.014) were all significantly lower in women with longer
duration of sleep (Table 2a). Likewise, SBP (p=0.016), DBP (p=0.017) and
MAP (p=0.014) were significantly lower in women with better efficiency
of sleep (Table 2a). No significant difference in BP was found in women
with different sleep qualities during the 2nd and
4th visits (Table 2a). DBP (p=0.011) and MAP (p=0.027)
were significantly lower in subjects with better sleep efficiency during
the 3rd visit (Table 2).
When overall sleep and BP were assessed throughout the whole pregnancy,
Lower PSQI score (p<0.001), shorter sleep latency (p=0.008)
and better sleep efficiency ((p=0.008) were found to be correlated to
lower DBP (Table 2b). Longer sleep duration was associated with lower
SBP (p=0.049) and DBP (p=0.008) (Table 2b).
Assessment of the overall relationship between sleep and uterine artery
doppler throughout pregnancy showed that poorer sleep quality (higher
PSQI, longer sleep latency, shorter sleep duration and worse sleep
efficiency) were associated with higher UA PI (Table 3). Patients with
higher PSQI and shorter sleep duration were also found to have higher UA
RI (Table 3).