【Abstract】
Objectives:The relative contributions of vitamin D status to pregnancy
complications are not fully understood. We investigated the correlation
between vitamin D status and pregnancy outcomes.
Design: Prospective analysis of cases
Setting: China
Population or Sample: A total of 1766 pregnant women were admitted
to The Eighth Affiliated Hospital, Sun Yat-sen University and Guangdong
Women and Children Hospital between January 2019 and December 2020.
Methods: This prospective cohort study was performed on women
who paid antennal visits during their whole gestation. Serum
25-hydroxyvitamin D [25(OH)D] concentrations were measured among
women before 24 weeks of gestation. Associations between maternal
vitamin D status, maternal characteristics, and pregnancy outcomes were
assessed. The adjusted odds ratio (OR) for adverse pregnancy outcomes
was calculated using the logistic regression analysis.
Results: Among all participants, 192(10.87%),
1023(57.93%) and 551(31.20%) were defined as vitamin D sufficiency,
insufficiency, and deficiency, respectively. There was no significant
difference in vitamin D between pregnant women with adverse pregnancy
outcomes and those without adverse pregnancy outcome. Neither vitamin D
deficiency nor insufficiency was associated with adverse pregnancy
outcomes compared with vitamin D sufficiency. Risks of adverse outcomes
were as follows: GDM (OR=0.72 95%CI 0.46-1.14; OR=0.86 95%CI
0.57-1.30), SGA (OR=1.38 95%CI 0.73-2.60; OR=1.28 95%CI 0.70-2.34),
early preterm delivery (OR=0.59 95%CI 0.13-2.70; OR=0.84 95%CI
0.23-3.00), PE (OR=3.44 95%CI 0.43-27.52; OR=2.40 95%CI 0.31-18.50),
and postpartum hemorrhage (OR=0.58 95%CI 0.33-1.03; OR=0.81 95%CI
0.49-1.35).
Conclusions: Low vitamin D status may not be associated with
adverse pregnancy outcomes. Vitamin D screening in all pregnant women
seems not reasonable.
Keywords: Vitamin
D;gestational diabetes mellitus; small for gestational age; preterm
delivery; 25-hydroxyvitamin D; pregnancy
【Introduction】
Vitamin D is an essential nutritional factor, which has received
increasing attention in recent years, due to its primary role in bone
remodeling, calcium homeostasis, and muscle
functioning[1].During pregnancy, vitamin D plays
an important role in maternal metabolism and embryogenesis, especially
fetal skeletal development and calcium
homeostasis[2]. Vitamin D deficiency means that
the serum levels of vitamin D are inadequate to support the daily body
needs[3]. Numerous clinical studies have reported
that large proportions of global populations are vitamin D “deficiency
”, including pregnant women[1, 4, 5].Some
researches have also concluded many adverse effects of maternal vitamin
D deficiency[6-8]. Animal experiments showed that
vitamin D deficiency during pregnancy could lead to reproductive
dysfunction and neurobehavioral developmental disorders in adult
offspring[9].
Vitamin D level is commonly assessed by the measurement of
25-hydroxyvitamin D[25(OH)D] level, which is considered the best
marker of vitamin D status. According to the recommendation and
consensus of the Committee of the Institute of Medicine (IOM, USA), most
experts agree to define vitamin D insufficiency as 25(OH)D between
30-49.9nmol/L, and 25(OH)D levels of <30nmol/L are considered
to be indicative of vitamin D deficiency[10]. This
array of values is for everyone: children or adults, pregnant or
not,because vitamin D metabolism is markedly different during pregnancy
compared to nonpregnancy, significant changes in calcium and vitamin D
metabolism occur during pregnancy to meet the needs of growing
fetuses[11]. Unfortunately, it is unclear whether
the recommended 25(OH)D levels discussed above are suitable for pregnant
women. In fact, vitamin D insufficiency and deficiency are very common
in pregnant women and newborns population, almost one in three
newborns or one in five pregnant women were found below
25nmol/L[7]. However, it is still controversial
whether vitamin D “deficiency” or “insufficiency” as defined by the
IOM criteria is really related to adverse pregnant outcomes.
In this prospective study of two tertiary hospitals in South China, our
aim was to investigate the association between vitamin D status before
24 gestational weeks and adverse pregnancy outcomes that were mainly
reported recent years[12] [gestational diabetes
mellitus (GDM), small for gestational age (SGA), early preterm delivery
(preterm delivery before 34 weeks), preeclampsia (PE), and postpartum
hemorrhage].