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ORIGINAL ARTICLE
Year : 2017  |  Volume : 1  |  Issue : 2  |  Page : 77-79

Influence of vitamin D level in the second trimester of pregnancy on the complications of chinese pregnant women and fetuses


1 Department of obstetrical, Changning Maternity and Infant Health Hospital, Shanghai 200335, China
2 Department of Endocrine, Tongji Hospital, Tongji University School of Medicine, Shanghai 200065, China
3 Department of Gynecology, Shanghai First Maternity and Infant Hospital, Tongji University School of Medicine, Shanghai 201204, China

Date of Web Publication17-Oct-2017

Correspondence Address:
Dong Zhao
Department of Gynecology, Shanghai First Maternity and Infant Hospital, Tongji University School of Medicine, No. 2699 Gaokexi Road, Shanghai 201204
China
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/2096-2924.216858

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  Abstract 


Background: Vitamin D has been found to have more biological effects beyond the traditional research range, which involve in immunoregulation, occurrence, and development of tumor, reproduction, cell differentiation, and so forth. Herein, the influence of Vitamin D level in the second trimester of pregnancy on the Chinese pregnant women and fetal weight was investigated.
Methods: Totally 1,612 pregnant women were followed up during the study, the 25-hydroxyvitamin D (25(OH)D) level was measured with ELISA at the 16th gestational week, and the fasting blood glucose was measured with hexokinase method using an automatic biochemistry analyzer at the same time. At week 24, oral glucose tolerance test (OGTT) was performed to test the blood glucose level (fasting blood glucose, 1 h and 2 h after oral administration of glucose). Besides, other indices (e.g., fetal birth weight) were recorded and analyzed by SPSS version 19.0 software.
Results: Pearson's correlation analysis indicated that the serum 25(OH)D had a negative correlation with blood glucose at 1 h after oral glucose administration at week 24 in OGTT (correlation coefficient: −0.03, P = 0.01). However, it did not have correlations with the fasting blood glucose at weeks 16 and 24 as well as the blood glucose at 2 h after oral glucose administration at week 24. The Pearson's correlation analysis was used to analyze the correlation between Vitamin D level in the pregnant women and fetal birth weight, and there was no correlation between them.
Conclusion: The Vitamin D level in the second trimester of pregnancy had a negative correlation with blood glucose and had no correlation with fetal birth weight.

Keywords: Blood Glucose; Low Birth Weight; Second Trimester of Pregnancy; Vitamin D


How to cite this article:
Yang L, Song LG, Wang YH, Zhao D. Influence of vitamin D level in the second trimester of pregnancy on the complications of chinese pregnant women and fetuses. Reprod Dev Med 2017;1:77-9

How to cite this URL:
Yang L, Song LG, Wang YH, Zhao D. Influence of vitamin D level in the second trimester of pregnancy on the complications of chinese pregnant women and fetuses. Reprod Dev Med [serial online] 2017 [cited 2020 Jun 5];1:77-9. Available from: http://www.repdevmed.org/text.asp?2017/1/2/77/216858




  Introduction Top


Vitamin D plays a very important role in the calcium–phosphorus metabolism and bone metabolism. Besides, it has been proved to take effects in the pathogenetic processes of immune diseases, tumors, and diabetes, and has been applied in the corresponding therapies.[1] Meanwhile, Vitamin D has also been reported to regulate the emotion and spirit.[2] Therefore, more and more attention has been paid to the research of Vitamin D.

The lack or low level of Vitamin D during pregnancy will not only influence the pregnant woman herself, but also affect the fetus, for example, developmental retardation, bone mineralization, and complications in the early stage of birth.[5] It has been proved that the lack of Vitamin D was related with various pregnancy complications and fetal birth defects, for example, preeclampsia, gestational diabetes mellitus (GDM), premature, spontaneous abortion, intrauterine growth restriction, and low-birth-weight infants. Furthermore, it can also affect the neonatal Apgar score.[4] However, the current data are not consistent, and the best level of prenatal Vitamin D is still not clear. Thus, the aim of the study was to explore the correlations of serum Vitamin D level in pregnant women with blood glucose at 1 h after oral glucose administration and fetal weight, which could provide the basis for the supplement of Vitamin D for Chinese pregnant women.


  Methods Top


Study population

The prenatal examination data were collected from April 2014 to June 2015 after obtaining signed informed consents from the pregnant women. All the examinations were completed at Shanghai Changning Maternity and Infant Health Hospital.

Oral glucose tolerance test (OGTT)

Detection method for OGTT: the patients were fasted at 1 day before the OGTT. After 8–14-h fasting, the test was performed on the next morning (no later than 9:00 a.m.). The patients should maintain appropriate exercises and keep regular diet from 3 days before the test. The acceptable daily intake of carbohydrate was ≥150 g. During the test, the patients should sit quietly, without allowance of smoking and eating. Examination method: the fasting blood glucose was measured at first, and 75 g anhydrous glucose dissolved in 300 mL water was drunk off within 5 min by the patients. Then, venous blood glucose was measured at 1 h and 2 h after oral glucose administration (the time of beginning of drinking was recorded as 0 min). Hexokinase method was used to measure the blood glucose in plasma.

Defining variables and diagnostic criteria

Diagnostic criteria for GDM

Normal value after oral administration of 75 g glucose: fasting blood glucose <5.1 mmol/L, blood glucose at 1 h after glucose administration <10.0 mmol/L, and blood glucose at 2 h after glucose administration <8.5 mmol/L. Any abnormality in the above blood glucose values was diagnosed as GDM.

Statistical method

SPSS software version 19.0 (SPSS Inc., Chicago, IL, USA) was used to analyze the data. After the normal distribution test, the data were analyzed by the Pearson's correlation analysis, Spearman correlation analysis, and partial correlation analysis. P < 0.05 was termed as statistical significance.


  Results Top


Correlation between Vitamin D level in the second trimester of pregnancy and blood glucose level

The Pearson's correlation analysis indicated that the serum 25-hydroxyvitamin D (25(OH)D) had a negative correlation with the blood glucose at 1 h after oral glucose administration at week 24 (correlation coefficient: −0.03, P = 0.01) [Figure 1]. However, it did not have correlations with the fasting blood glucose at weeks 16 and 24 as well as the blood glucose at 2 h after oral glucose administration at week 24 (P > 0.05). After correction by body mass index and age, the above correlations still existed.
Figure 1: Correlation between the serum 25(OH)D level of pregnancy at Week 16 and the blood glucose level at 1 h after oral glucose administration at Week 24. (a) Original image. (b) Local enlarged image.

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Correlation between Vitamin D level in the second trimester of pregnancy and fetal weight

The Pearson's correlation analysis was used to analyze the correlation between the Vitamin D level in pregnant woman and fetal birth weight, and there was no correlation between them [Table 1].
Table 1: Correlation between the blood glucose level and the fetal birth weight

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  Discussion Top


Influencing mechanism of Vitamin D on blood glucose

Influence of Vitamin D on insulin secretion

Vitamin D is closely related to insulin secretion, which play an important role in controlling glucose stability. Previously, it was shown that the level of Vitamin D was negatively correlated with the degree of diabetes and that the vitamin D deficiency was associated with a negative correlation with GDM risk.[2] The study showed that the proportion of patients with Vitamin D deficiency (24%, P <0.001) was significantly higher than that of normal Vitamin D (16%)[3], especially Type 1 diabetes. 25(OH)D is closely related with the function of insulin secretion.

Vitamin D and insulin resistance

Vitamin D has been reported to have a regulatory effect on blood glucose.[4] First, the Vitamin D receptor (VDR) genes are relevant to the blood glucose level. Besides, the polymorphisms of Vitamin D synthesis-related coding genes, degradation-related genes, and ligand-dependent signal transduction pathway-related genes are also relevant to the blood glucose level.[5] For example, Allele f in the FokI of VDR gene easily leads to insulin resistance. Second, the combination of Vitamin D and its receptor influences the function of pancreatic β-cells and insulin secretion, by regulating the intra- and extra-cellular calcium concentration. Furthermore, Vitamin D can directly stimulate the expression of insulin receptor on the cytomembrane, influence the transport of glucose, and further regulate glucose homeostasis. It increases the insulin sensitivity to target cells (liver, skeletal muscle, and adipose tissue). All these mechanisms suggest that Vitamin D can influence the blood glucose level.

Vitamin D and inflammatory response

Except for the effect in the calcium–phosphorus metabolism, 25(OH)D also plays a very important role in the signal transfer and rapid reaction (i.e., ion channel), as a chemical messenger.

Above all, the influences of Vitamin D on the blood glucose are caused by many factors, including insulin secretion, insulin resistance, and inflammatory response. All these factors result in the negative correlation between serum 25(OH)D and the blood glucose at 1 h after oral glucose administration at week 24.

Influence of Vitamin D on fetal birth weight

The correlation between Vitamin D and fetal birth weight has been reported in different conclusions. Some investigations in China reported that the serum 25(OH) D level during pregnancy had a positive correlation with the newborn birth weight,[6] which was similar as most of the data from other overseas studies.[7] Only a few studies reported that there was no correlation as ours. The possible reasons are as follows: (1) Vitamin D influences blood glucose, and the blood glucose directly influences the fetal growth and development. (2) Vitamin D level is related with immunoregulation, and the changes of immunity will directly influence the fetal weight. (3) It has been proved that Vitamin D was relevant to coronary heart disease and atherosclerosis, and Vitamin D level directly influenced blood vessels. (4) Recently, it has been reported that the lack of Vitamin D in pregnant women may cause increase in corticosterone and decrease in placental weight. Meanwhile, the low Vitamin D level leads to decrease in 11β-hydroxysteroid dehydrogenase Type II, which protects fetus from the inappropriate glucocorticoid exposure through inactivation of glucocorticoids. All the above mechanisms can result in fetal weight changes by influencing mother or directly affecting fetus. However, the weight is regulated by many factors, which has a positive correlation with blood glucose and negative correlation with immune factors, blood vessels, and hydrocortisone. Vitamin D influences the fetal weight by many factors, and the changes are complicated, finally showing no correlation between them.


  Conclusions Top


The serum 25(OH)D in the second trimester of pregnancy had a negative correlation with the blood glucose at 1 h after oral glucose administration at week 24 and had no correlation with fetal birth weight.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Zhou WD, Zhang PB. Progress in the effects of Vitamin D receptor and function of Vitamin D. Chin J Child Heal Care 2008;5:560-2.  Back to cited text no. 1
    
2.
Wang MJ, Niu JM, Wen JY, Wang XQ, Liang YX. Effect of Pregnancy Management of Gestational Diabetes on Pregnancy Outcome. Guangdong Med J 2009;30:900-1.  Back to cited text no. 2
    
3.
Arnold DL, Enquobahrie DA, Qiu C, Huang J, Grote N, VanderStoep A, et al. Early pregnancy maternal vitamin D concentrations and risk of gestational diabetes mellitus. Paediatr Perinat Epidemiol 2015;29:200-10. doi: 10.1111/ppe.12182.  Back to cited text no. 3
    
4.
Kiely M, Hemmingway A, O'Callaghan KM. Vitamin D in pregnancy: current perspectives and future directions. Ther Adv Musculoskel Dis 2017;9:145-54. doi: 10.1177/ 1759720X17706453.   Back to cited text no. 4
    
5.
Zhang C, Qiu C, Hu FB, David RM, van Dam RM, Bralley A, et al. Maternal plasma 25-hydroxyvitamin D concentrations and the risk for gestational diabetes mellitus. PLoS One 2008;3: e3753. doi: 10.1371/journal.pone.0003753.  Back to cited text no. 5
    
6.
Chen YH. Maternal Vitamin D status during pregnancy is associated with fetal intra-uterine growth restriction. Anhui Medical University 2014 (Doctoral thesis).  Back to cited text no. 6
    
7.
Pérez-López FR, Pasupuleti V, Mezones-Holguin E, Benites-Zapata VA, Thota P, Deshpande A, Hernandez AV, et al. Effect of vitamin D supplementation during pregnancy on maternal and neonatal outcomes: a systematic review and meta-analysis of randomized controlled trials. Fertil Steril 2015;103:282-3. doi:10.1016/j.fertnstert.2015.02.019.  Back to cited text no. 7
    


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