**4.1 Gestational hypertension and preeclampsia**

Elevated blood pressure that appears after 20 weeks without proteinuria or other findings is called gestational hypertension (GHT). This problem is confirmed by systolic blood pressure (SBP) ≥160 or diastolic blood pressure (DBP) ≥110 mmHg for anyone (confirmed over a few minutes) or SBP ≥140 or DBP ≥90 mmHg after 20 weeks (confirmed over 4 hours) observing for the first time [38]. At least 25% of women with GHT is predisposed to PET [38]. PET is diagnosed by high blood pressure (systolic blood pressure >140 mmHg, diastolic blood pressure >90 mmHg) after 20 weeks of gestation along with proteinuria (>300 mg/day) and other organ dysfunction including liver involvement, hematological disturbance, neurological

**37**

*Maternal Vitamin D Status among Different Ethnic Groups and Its Potential Contribution…*

or renal complications [39]. The pathogenesis of PET involves releasing the angiogenic factors to the maternal circulation which causes insufficient remodeling and trophoblastic invasion of spiral arteries. It leads to shallow implantation and hypoxia, and even release of inflammatory mediators [40]. PET is a multifactorial outcome that has not been fully understood yet; however, maternal calcium status is suggested to be an important factor. Therefore, vitamin D due to its role in calcium hemostasis might have an impact on PET [41]. In addition, vitamin D can be protective of placental vasoconstriction and consequently, PET because of its immunomodulatory effect. Also, vitamin D is a regulator of endothelial and vascular smooth muscle cell proliferation through which regulates blood pressure

Systematic reviews and meta-analysis, including cross-sectional, longitudinal, cohort, ecological, and observational studies, indicate inconsistent results regarding the association between vitamin D deficiency and PET. Some studies reported an increased risk of PET women with vitamin D deficiency in pregnancy in contrast with others [43–45]. This contradiction of finding can be explained by different vitamin D assessment methods, criteria applied to define vitamin D deficiency, different season and trimester in studies [44]. Therefore, associations are inconclusive, often contradictory, confounded, and lack causality. In addition, supplementation helps to raise the level of maternal vitamin D; however, there is no significant reduction of PET risk with a higher level of vitamin D status [22, 46]. In this regard, more observational and interventional studies with different designs are needed.

Gestational diabetes mellitus (GDM) is glucose intolerance developed or first diagnosed during pregnancy. Criteria for recognition GDM are controversial [47]; according to World Health Organization (WHO), fasting blood glucose above 92–125 mg/dl and/or 2-h glucose greater than 153–199 mg/dl after glucose intake of 75 g are considered as diabetes mellitus in pregnancy as is a random plasma value of above 200 mg/dl with diabetes symptoms [48, 49]. Vitamin D plays a crucial role in glucose homeostasis through several mechanisms. The first is regulating calcium, which is a regulator for the production and secretion of insulin by the endocrine pancreas. Its second role involves enhancing insulin sensitivity of the target cells in adipose tissues, liver, and skeletal muscles. Moreover, the immune cell regulation role of vitamin D protects β-cells from damaging and improves its function [50, 51]. Although vitamin D deficiency can be associated with the pathogenesis of diabetes mellitus type 1 and type 2, its role in GDM is not conclusive [43]. Conflicting results have been found in case-control, prospective cohort studies, and reviews looking into the risk of GDM with vitamin D status [46]. Some review studies indicate that pregnant women with significant lower 25(OH)D had a higher risk of GDM by 40–60% [45, 52], while in systematic and critical reviews, most studies failed to support the association between vitamin D status and GDM prevention [43, 44]. Thus, more large-scale prospective studies are needed to evaluate this association.

Depression after delivery is a common psychiatric condition which is called postpartum depression (PPD) [53]. Vitamin D as a neurosteroid suggested having a role in various brain functions and depression by several potential mechanisms. Firstly, Vitamin D plays as a neurotransmitter, neuro-immunomodulation, and neuroprotection in the brain [54]. Secondly, vitamin D has a role in synthesizing norepinephrine and dopamine, which are involved in mood disorders.

*DOI: http://dx.doi.org/10.5772/intechopen.90766*

via Renin-Angiotensin-Aldosterone system (RAAS) [42].

**4.2 Gestational diabetes mellitus (GDM)**

**4.3 Postpartum depression (PPD) or anxiety**

*Maternal Vitamin D Status among Different Ethnic Groups and Its Potential Contribution… DOI: http://dx.doi.org/10.5772/intechopen.90766*

or renal complications [39]. The pathogenesis of PET involves releasing the angiogenic factors to the maternal circulation which causes insufficient remodeling and trophoblastic invasion of spiral arteries. It leads to shallow implantation and hypoxia, and even release of inflammatory mediators [40]. PET is a multifactorial outcome that has not been fully understood yet; however, maternal calcium status is suggested to be an important factor. Therefore, vitamin D due to its role in calcium hemostasis might have an impact on PET [41]. In addition, vitamin D can be protective of placental vasoconstriction and consequently, PET because of its immunomodulatory effect. Also, vitamin D is a regulator of endothelial and vascular smooth muscle cell proliferation through which regulates blood pressure via Renin-Angiotensin-Aldosterone system (RAAS) [42].

Systematic reviews and meta-analysis, including cross-sectional, longitudinal, cohort, ecological, and observational studies, indicate inconsistent results regarding the association between vitamin D deficiency and PET. Some studies reported an increased risk of PET women with vitamin D deficiency in pregnancy in contrast with others [43–45]. This contradiction of finding can be explained by different vitamin D assessment methods, criteria applied to define vitamin D deficiency, different season and trimester in studies [44]. Therefore, associations are inconclusive, often contradictory, confounded, and lack causality. In addition, supplementation helps to raise the level of maternal vitamin D; however, there is no significant reduction of PET risk with a higher level of vitamin D status [22, 46]. In this regard, more observational and interventional studies with different designs are needed.

#### **4.2 Gestational diabetes mellitus (GDM)**

Gestational diabetes mellitus (GDM) is glucose intolerance developed or first diagnosed during pregnancy. Criteria for recognition GDM are controversial [47]; according to World Health Organization (WHO), fasting blood glucose above 92–125 mg/dl and/or 2-h glucose greater than 153–199 mg/dl after glucose intake of 75 g are considered as diabetes mellitus in pregnancy as is a random plasma value of above 200 mg/dl with diabetes symptoms [48, 49]. Vitamin D plays a crucial role in glucose homeostasis through several mechanisms. The first is regulating calcium, which is a regulator for the production and secretion of insulin by the endocrine pancreas. Its second role involves enhancing insulin sensitivity of the target cells in adipose tissues, liver, and skeletal muscles. Moreover, the immune cell regulation role of vitamin D protects β-cells from damaging and improves its function [50, 51]. Although vitamin D deficiency can be associated with the pathogenesis of diabetes mellitus type 1 and type 2, its role in GDM is not conclusive [43]. Conflicting results have been found in case-control, prospective cohort studies, and reviews looking into the risk of GDM with vitamin D status [46]. Some review studies indicate that pregnant women with significant lower 25(OH)D had a higher risk of GDM by 40–60% [45, 52], while in systematic and critical reviews, most studies failed to support the association between vitamin D status and GDM prevention [43, 44]. Thus, more large-scale prospective studies are needed to evaluate this association.

#### **4.3 Postpartum depression (PPD) or anxiety**

Depression after delivery is a common psychiatric condition which is called postpartum depression (PPD) [53]. Vitamin D as a neurosteroid suggested having a role in various brain functions and depression by several potential mechanisms. Firstly, Vitamin D plays as a neurotransmitter, neuro-immunomodulation, and neuroprotection in the brain [54]. Secondly, vitamin D has a role in synthesizing norepinephrine and dopamine, which are involved in mood disorders.

*Vitamin D Deficiency*

NORDEN [24]

**Table 1.**

be performed.

section.

pregnant women and their infants. The discrepancies in some factors, including different measurement tools of vitamin D levels, various patient populations and different sample sizes that were used in studies, might explain the differences in the recommendations. Because of conflicting evidences, identifying sufficient and upper-limit amount of vitamin D for pregnant women requires further research to

*Committee on Nutrition; EFSA, European Food Safety Authority. Table adapted from Kiely et al. [27].*

*Summary of the current dietary recommendations for vitamin D in pregnant women.*

**Agency Countries 25(OH)D threshold (nmol/L) Vitamin D intake** 

IOM [1] USA/Canada <30 40 ≥50 10 15 —

SACN [25] UK <25 — ≥25 — 10 — EFSA [26] EU — — ≥50 — — 15 *25(OH)D, 25-hydroxyvitamin D; EAR, estimated average requirement; RI, recommended (individual) intake; AI, adequate intake; IOM, Institute of Medicine; NORDEN, Nordic Council of Ministers; SACN, Scientific Advisory* 

**average**

Nordic <30 — ≥50 7.5 10 —

**Individual target**

**Deficiency Population** 

**(μg/d)**

**EAR RI AI**

**4. Maternal vitamin D status and adverse pregnancy outcomes**

consensus on the optimal vitamin D status during pregnancy.

**4.1 Gestational hypertension and preeclampsia**

Numerous studies have reported pleiotropic role of vitamin D in pregnancy. Maternal Hypovitaminosis D during pregnancy is related to pregnancy related disorders. Complications caused by low serum measurement of 25(OH)D include gestational hypertension (GHT), PET, gestational diabetes mellitus (GDM), timing and mode of delivery, postpartum depression or anxiety, bacterial vaginosis, and other outcomes such as anemia and lipid disorders, which are discussed in this

It should be noted that, there is not enough evidence to support a recommendation for screening all pregnant women for vitamin D deficiency but must be at least 20 ng/ml (50 nmol/L) for bone health [35]. Although some experts suggest vitamin D serum level of at least 32 ng/ml (80 nmol/L) for optimal state in pregnancy [36], some adverse effects have been reported at levels exceeding 70 nmol/L [37]. Consequently, due to the lack of standardized measurement procedures, there is no

Elevated blood pressure that appears after 20 weeks without proteinuria or other findings is called gestational hypertension (GHT). This problem is confirmed by systolic blood pressure (SBP) ≥160 or diastolic blood pressure (DBP) ≥110 mmHg for anyone (confirmed over a few minutes) or SBP ≥140 or DBP ≥90 mmHg after 20 weeks (confirmed over 4 hours) observing for the first time [38]. At least 25% of women with GHT is predisposed to PET [38]. PET is diagnosed by high blood pressure (systolic blood pressure >140 mmHg, diastolic blood pressure >90 mmHg) after 20 weeks of gestation along with proteinuria (>300 mg/day) and other organ dysfunction including liver involvement, hematological disturbance, neurological

**36**

Furthermore, vitamin D protects the brain from oxidative stress by preserving the antioxidant glutathione in the brain [55, 56]. Most studies suggested there is an inverse association between vitamin D serum in different stages of gestation and postpartum depression [57–59]. In contrast, some studies indicate no association [60, 61], and even increased risk of PPD with sufficient vitamin D concentrations (≥50 nmol/L) [62]. However, in a systematic review study, a few studies reported the role of vitamin D in this pregnancy outcome [44]. Thus, although postpartum depression might be associated with vitamin D deficiency, inconsistent results need for more extensive studies in this regard.
