Strengths and limitations
The strength of the present study is that the aORs of LBW and SGA
provide clear information for perinatal counseling. Owing to the large
study population, including >80,000 participants, our
results must be reliable. Since pregnant women have more sleep problems,
affected by gestational age and hormonal changes,24than their non-pregnant counterparts, the effect of MSD on fetal and
neonatal health may be a great concern for pregnant women. There is no
consensus on appropriate MSD required to prevent adverse obstetric
outcomes. Therefore, the present study may help to suggest adequate MSD
required to prevent LBW and SGA.
The present study has several limitations. First, MSD in the present
study is based on self-reported questionnaire data, which might have
resulted in an inaccurate calculation of actual MSD. In addition, MSD is
a volatile index because it varies daily in the individuals and may vary
with gestational age.24 Careful interpretation is
needed regarding these instabilities of MSD. Further study with
polysomnography and unified gestational age may preclude this
limitation. Second, we did not account for the quality of sleep by
evaluating factors such as time zone, division, where to sleep, and with
whom to sleep. We evaluated MSD as a simple quantitative measurement of
maternal sleep. Careful interpretation of the results is needed because
the quality of maternal sleep, in addition to MSD, may also affect
obstetric outcomes.