Arch Gynecol Obstet DOI 10.1007/s00404-014-3550-8
MATERNAL-FETAL MEDICINE
Relationship between preeclampsia and vitamin D deficiency: a case control study Rimpi Singla • Padma Gurung • Neelam Aggarwal Usha Dutta • Rakesh Kochhar
•
Received: 27 January 2014 / Accepted: 11 November 2014 Ó Springer-Verlag Berlin Heidelberg 2014
Abstract Purpose There is paucity of literature pertaining to association between vitamin D deficiency and preeclampsia from sunshine-rich countries like India. Further none of the studies have reported on relation with severity of preeclampsia. This study was carried out with a purpose of studying relation between vitamin D deficiency and preeclampsia and its complications. Methods Seventy-four nulliparous preeclamptic women with singleton pregnancy and without any known medical disorder and 100 healthy nulliparous controls of same age were enrolled. Serum vitamin D concentration of the two groups was compared. We also compared the vitamin D level of women with mild and severe preeclampsia and with or without various complications of preeclampsia. Results Eighty-four percent of women were vitamin D deficient. Mean serum vitamin D was significantly lower among cases (9.7 ± 4.95 ng/ml) as compared to controls (14.8 ± 6.68 ng/ml); p = 0.0001. Women with mild preeclampsia (9.44 ± 5.63 ng/ml) had similar vitamin D level as those with severe disease (9.8 ± 4.79 ng/ml) (p = 0.811). There was no difference in vitamin D level of women with eclampsia (p = 0.956) or imminent eclampsia (p = 0.310) and those without these complications. Conclusion There is high prevalence of vitamin D deficiency among pregnant women in India. Women with R. Singla P. Gurung N. Aggarwal (&) Department of Obstetrics and Gynecology, Post Graduate Institute of Medical Education and Research, Chandigarh, India e-mail: [email protected]; [email protected] U. Dutta R. Kochhar Department of Gastroenterology, Post Graduate Institute of Medical Education and Research, Chandigarh, India
preeclampsia had significantly lower vitamin D level as compared to normal women. Severity of the disease was not related to vitamin D level. Keywords Pregnancy
Preeclampsia Vitamin D deficiency
Introduction Preeclampsia is a pregnancy-specific syndrome characterized by hypertension and proteinuria, affecting approximately 2–10 % of pregnancies [1–3] and is the major cause of maternal and fetal morbidity and mortality worldwide [1, 3]. It contributes to major proportion of maternal deaths, up to 16 % in developed countries [4]. Various risk factors and preventive methods have been tested [1]. Still there are no definite preventive measures. Pathogenesis of preeclampsia is believed to involve maternal immune rejection of the placental cytotrophoblasts leading to inadequate remodeling and trophoblastic invasion of spiral arteries leading to shallow implantation and hypoxia and release of inflammatory mediators [5]. With the recognition of immunomodulatory properties of vitamin D, the role of this secosteroid hormone in normal placentation had been the subject of recent research. Vitamin D receptors [6] and 1-a hydroxylase [7] are expressed both in decidua and trophoblast cells, providing an evidence for role of vitamin D in placentation. Vitamin D deficiency has been widely reported among pregnant women in various countries [8–10]. Some studies have shown association between vitamin D deficiency (VDD) and preeclampsia [11, 12] and other adverse pregnancy outcomes [13]. Most of the studies are from countries situated in different latitudes generally away from equator. Vitamin D deficiency is also prevalent among
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pregnant women in India despite sunny climate and proximity to equator [14, 15]. Lack of sun exposure, skin pigmentation and dietary insufficiency are the main reasons. There is paucity of literature pertaining to association between VDD and preeclampsia from sun-rich country of India and the available studies are quite old [16]. None of the studies from India to the best of our knowledge have tried to find relation with severity of preeclampsia. Since preeclampsia contributes to 9 % of maternal deaths in India [4], finding relation with vitamin D deficiency may lead us to a non-expensive preventive measure. This would have widespread maternal health implications as so far we do not have definitive preventive measures. So, this study was conducted to study the prevalence of vitamin D deficiency and its relationship with preeclampsia and with the disease severity.
Materials and methods This case control study was conducted over a period of 18 months in a tertiary care referral institute in Northern India. A total of 71 pregnant preeclamptic women were recruited for this study after assessing their eligibility according to the selection criteria. Inclusion criteria were nulliparous preeclamptic women with live singleton pregnancy. Preeclampsia was defined as systolic blood pressure C140 mmHg and/or a diastolic pressure C90 mmHg, measured at separate occasions at least 4 h apart and proteinuria in a 24-h protein excretion C300 mg or 1? on random urine sample [17]. Severe preeclampsia was defined as systolic blood pressure C160 mmHg and/or diastolic pressure C110 mmHg and/or proteinuria in a 24-h protein excretion C5 gms or 3? on random urine sample. Associated symptoms and abnormal investigations like cerebral dysfunction (blurred vision, scotoma, headache, cerebrovascular accidents), epigastric or right upper quadrant pain, renal failure or oliguria B500 ml in 24 h, impaired liver function (serum transaminase levels two times normal or greater), thrombocytopenia 3 (B100,000 platelets/mm ), fetal growth restriction, HELLP (hemolysis, elevated liver enzymes, low platelets), coagulopathy, pulmonary edema, eclampsia (generalized convulsions) were also recorded. Women with preexisting medical conditions like rheumatoid arthritis, thyroid, hepatic or renal failure, metabolic bone disease, diabetes mellitus, malabsorption, chronic hypertension and lupus, or with multiple pregnancy, or history of intake of medications influencing bone, vitamin D or calcium metabolism e.g. Antiepileptic/theophylline/antitubercular drugs in the last 6 months were excluded. One hundred and three healthy nulliparous pregnant women with singleton pregnancy and no associated morbidity were recruited as
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controls from the same region in the same time frame. Written informed consent was obtained from all the women. Out of 103 controls, 3 eventually developed mild preeclampsia and so were taken up as cases. Relevant details like age, education, occupation, and socio-demographic factors were noted on a predesigned Performa. Blood sample for vitamin D level as well as serum calcium and alkaline phosphatase was collected at enrollment and immediately transported to the laboratory. Serum was separated by centrifugation and stored at 20 °C and analyzed by ELISA method (Immune Diagnostic Systems, UK). Deficiency was defined as serum level of \20 ng/ml, insufficiency as 20–30 ng/ml and optimum level as [30 ng/ml [18]. All the subjects were managed as per protocol of the institute. During the course of her pregnancy if the subject in control group developed preeclampsia then she was excluded from the control group and taken up as case. The study was approved by institute’s ethics committee and was performed in accordance with the ethics standards as laid down in Declaration of Helsinki. Primarily, we looked for difference in vitamin D status of preeclamptic women as compared to the controls. Further we looked for any relation between severity of preeclampsia, its complications and mode of delivery with vitamin D status. Secondarily, we studied the fetal outcomes as birth weight, stillbirth, neonatal complications, admission to neonatal intensive care unit (NICU) or neonatal nursery (NNN). The data were analyzed using SPSS version 17. Appropriate statistical tests were used as applicable. A ‘p’ value of B0.05 was considered significant.
Results Mean age in the preeclampsia (case) group was 25.22 ± 3.08 years and in the control group was 25.11 ± 3.12 years; the difference was not significant (p = 0.6). The mean gestation of cases was 34.5 ± 3.1 weeks and that in the controls was 35.8 ± 2.2 weeks. All the women were from same city or neighboring states living in within the latitudes of 30–32°N. The prevalence of vitamin D deficiency (vitamin D \20 ng/ml) in entire study population was 83.9 %. Only one woman that was in the control group had sufficient vitamin D level of [30 ng/ml. Mean systolic and diastolic blood pressure of cases were 156 ± 19.5 and 104 ± 10.5 mmHg while that of control group were 117 ± 4.7 and 75 ± 5.2 mmHg. Mean serum vitamin D was significantly lower among the cases (9.7 ± 4.95 ng/ml) compared to that of the controls (14.8 ± 6.68 ng/ml); p = 0.0001 (Table 1). Significantly higher proportion of subjects among the cases (93.2 %) were vitamin D deficient in comparison to the controls
Arch Gynecol Obstet Table 1 Vitamin D status of women with preeclampsia and various complications Vitamin D level (mean ± SD) ng/ml
P value
Table 2 Maternal and fetal outcome in vitamin D deficient preeclamptic patients Parameter
Vitamin D\20 ng/ ml (n = 69)
0.0001*
Vitamin D [20 ng/ml (n = 5)
p value
Cases (n = 74)
9.7 ± 4.95
Controls (100)
14.8 ± 6.68
Mild preeclampsia (17) Severe preeclampsia (57)
9.44 ± 5.63 9.80 ± 4.79
0.811
Imminent eclampsia Present (16)
8.82 ± 2.54
0.310
Absent (58)
9.81 ± 5.43
Normal
Present (7)
9.62 ± 4.46
Absent (67)
9.73 ± 5.03
Cesarean section Forceps
5 (100 %)
0 (0 %)
Eclampsia
*
0.012
Normal vaginal (41)
11.21 ± 5.70
Cesarean section (28)
8.06 ± 3.18
Condition at birth Live born (70) Still born (4)
0.559 9.81 ± 4.81 8.46 ± 7.27 0.905
Present (35)
10.04 ± 5.29
Absent (35)
9.89 ± 4.66
Sepsis
0.921
Present (20)
9.87 ± 4.22
Absent (50)
10.0 ± 5.25
Admission to NICU/NNN
16 (100 %)
0
0.215
Eclampsia
7 (100 %)
0
0.454
36 (52.2 %)
5 (100 %)
0.116
28 (100 %)
0 (0 %)
Neonatal outcomea
6.8 ± 1.46
NNJ
Imminent eclampsia
Mode of delivery (n/74)
0.956
Mode of delivery
Forceps (5)
Complications (n/74)
HIE
3/66
0/4
0.623
IVH
2/66
0/4
0.691
NNJ
32/66
3/4
0.643
Sepsis
19/66
1/4
0.660
Admission to NICU/NNN
25/66
1/4
0.410
Neonatal mortality
9/66
1/4
0.705
HIE Hypoxic ischemic encephalopathy, IVH intraventricular hemorrhage, NNJ neonatal jaundice, NICU neonatal intensive care unit, NNN neonatal nursery a
Livebirths
0.322
Present (26)
9.2 ± 4.02
Absent (44)
10.4 ± 5.41
NNJ neoanatal jaundice, NICU neonatal intensive care unit, NNN Neonatal nursery * p value of \0.05 is significant
(78 %); p = 0.006. Vitamin D concentration showed negative correlation with both systolic (r = -0.370; p = 0.001) and diastolic blood pressure (r = -0.387; p = 0.001). Out of 74 cases, 17 (23 %) had mild preeclampsia and 57 (77 %) had severe form of preeclampsia. Mean vitamin D level of women with mild preeclampsia and those with severe disease was similar (p = 0.811) (Table 1). Sixteen subjects had imminent eclampsia. Though mean vitamin D concentration did not differ with presence or absence of imminent eclampsia (p = 0.310), none of the subjects with vitamin D level of [20 ng/ml had this complication (Table 2). Also, mean value among women with or without eclampsia was similar but all of the seven women who had eclampsia were vitamin D deficient (\20 ng/ml) (Table 2). Among the cases, vitamin D level of patients requiring cesarean section was significantly lower than those having normal vaginal delivery (p = 0.022). The main
indication of cesarean section among cases was fetal distress (in 20 women) and abruptio placentae (in 5 women). For the entire study population of 174 subjects also, vitamin D level in women undergoing cesarean was significantly lesser than vaginal delivery (10.71 ± 6.32 vs. 13.45 ± 6.45 ng/ml; p = 0.013). Birth weight showed positive correlation with the vitamin D concentration (r = 0.245; p = 0.001). Gestational age at delivery had direct correlation with vitamin D concentration (r = 0.313; p = 0.001). No difference was observed between vitamin D levels of mothers whose babies suffered with various neonatal complications. Mean vitamin D level of rural women (11.40 ± 6.59 ng/ml) was significantly lesser than urban women (13.42 ± 6.38 ng/ml); p = 0.05. Vitamin D concentration had positive correlation with serum calcium (r = 0.245; p = 0.05) but no relation to alkaline phosphatase (r = 0.023; p = 0.848).
Discussion Preeclampsia is associated with high maternal and fetal morbidity and mortality [4]. Recent research has pointed towards some role of vitamin D deficiency in pathogenesis
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of preeclampsia. While we have a fair number of studies from developed countries, but very few investigators have studied the relation between vitamin D deficiency and preeclampsia from India. First of all, our study showed alarmingly high prevalence of vitamin D deficiency among pregnant women. Nearly, 84 % of the women were deficient and rest of them mostly had insufficient levels. The reasons may be lack of sun exposure and fortification of food with vitamin D, and irregular intake of prenatal vitamins. Urban women had better vitamin D status than rural women; this may be due to more of outdoor activity in urban women than their rural counterparts during pregnancy. Though direct comparisons between studies are not possible due to inconsistent definitions of deficiency and insufficiency [8–10], most of them including the present one show high prevalence of preeclampsia among vitamin D deficient women. In previous studies deficiency was defined as serum level of less than 15 ng/ml but now, based on array of some biomarkers, it has been recognized that minimum serum concentration of 20 ng/ml is desirable. Hence, deficiency is now defined as serum level of \20 ng/ml [18]. We found significant association between vitamin D deficiency and preeclampsia. Lower serum concentration among preeclamptic women signifies the underlying role of vitamin D deficiency in pathogenesis of the disease. Women in the control group had similar age, same parity (all nulliparous), belonged to same geographical area and were recruited in same time frame as cases, hence eliminating most of the confounding factors. Bodnar et al. [10] found a fivefold increase in the odds of preeclampsia with early pregnancy vitamin D level of less than 37.5 nmol/ liter (15 ng/ml). Similarly, in another study, subjects with early onset severe preeclampsia were noted to have decreased total vitamin D levels relative to healthy controls (18 vs. 32 ng/mL, p \ 0.001) [19]. One clinical trial addressing role of vitamin D in preventing preeclampsia supports a potential role of vitamin D in the prevention of preeclampsia. It reported that supplementation with a multivitamin/mineral supplement and halibut liver oil (containing 900 IU/d vitamin D) provided at 20 week gestation reduced the odds of preeclampsia by 32 % [20], Another study randomized 400 women at 20–24 week gestation to vitamin D (1200 IU/d) and calcium (375 mg/d) supplements or no treatment and found non-significant reduction in the incidence of preeclampsia in the treated group compared with the untreated (6 vs. 9 %) [16]. None of the above trials used vitamin D alone, hence exact role in prevention cannot be commented up on. We did not find significant difference in vitamin D level between mild and severe disease. Though all our patients who developed imminent eclampsia or eclampsia had vitamin D level of \20 ng/ml approaching at a definite
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conclusion is not feasible as most of the patients were vitamin D deficient only. Mean serum levels among the women with or without imminent eclampsia or eclampsia were not significantly different. This suggests that vitamin D has preventive role, and once preeclampsia sets in it may not be effective altering the course or controlling the severity. After the onset of disease, woman’s own system i.e. the level of oxidative stress, inflammatory mediators, vascular endothelial damage, immune responses etc. dictates the course. Mode of delivery was affected by vitamin D status as all of the women from disease group requiring cesarean section or forceps delivery were vitamin D deficient. Serum vitamin D concentration of women with preeclampsia requiring cesarean section (all were primary cesareans) was significantly lower than that of women having normal delivery. Results remained significantly different in the similar fashion for the entire study population of 174 women. Similar result was seen in a study by Merewood et al.; there was an inverse association with having a cesarean section and serum vitamin D levels. Women with 25(OH) D concentrations \37.5 nmol/L were four times more likely to have a cesarean delivery than women with vitamin D concentrations [37.5 nmol/L [21]. All the women undergoing forceps delivery had severe deficiency (serum vitamin D level of less than 10 ng/ml); this may be associated with poor muscle function. Most important reasons for forceps application were prolonged second stage and fetal bradycardia. Birth weight showed positive correlation with vitamin D level. So far many studies have reported association between low birth weight and vitamin D deficiency. Marya et al. [22] from India, reported higher body weight, crown heel length, head circumference and mid arm circumference in mothers who received two doses of 6,00,000 IU of vitamin D3 during third trimester pregnancy compared to those who did not receive vitamin D. Maternal vitamin D deficiency is also associated with low serum vitamin D levels in the newborn [10, 15, 23]. Overall preeclampsia was associated with significant maternal and fetal morbidity. There were four still births in the disease group. Newborns of preeclamptic women had significant morbidity in the form of sepsis, jaundice, hypoxic ischemic encephalopathy (HIE) and admission to NICU mainly due to premature inductions in maternal interest. Mothers whose neonates faced various neonatal complications had no difference in their vitamin D status as compared to those without respective complication. So, we found high prevalence of hypovitaminosis D among pregnant women in India. Women with preeclampsia had significantly lower vitamin D level as compared to normal women, suggesting its role in pathogenesis of preeclampsia. Severity of the disease was not
Arch Gynecol Obstet
related to vitamin D level. There was high incidence of cesarean delivery among vitamin D deficient women. Birth weight showed improvement with vitamin D status. Overall, vitamin D deficiency was found to be related to adverse maternal and fetal outcome. Conflict of interest We report no financial relation with any organization. We declare that authors have full control of the primary data. The authors declare that they have no conflict of interest.
References 1. Duckitt K, Harrington D (2005) Risk factors for pre-eclampsia at antenatal booking: systematic review of controlled studies. BMJ 330:565 2. Guidotti R (1988) Geographic variation in the incidence of hypertension in pregnancy. Am J Obst Gynecol 158:80–83 3. Roberts CL, Ford JB, Algert CS, Antonsen S, Chalmers J, Cnattinguis S et al (2011) Population-based trends in pregnancy hypertension and pre-eclampsia: an international comparative study. BMJ Open 1:e000101. doi:10.1136/bmjopen-2011-000101 4. Khan KS, Wojdyla D, Say L, Gu¨lmezoglu AM, Van Look PFA (2006) WHO analysis of causes of maternal death: a systematic review. Lancet 367:1066–1074 5. Evans KN, Bulmer JN, Kilby MD (2004) Hewison M Vitamin D and placental-decidual function. J Soc Gynecol Investig 11:263–271 6. Norman AW (2006) Vitamin D receptor: new assignments for an already busy receptor. Endocrinology 147:5542–5548 7. Zhender D, Bland R, Williams MC, McNinch RW, Howie AJ, Stewart PM et al (2001) Extrarenal expression of 25-hydroxyvitamin d(3)-1 alpha-hydroxylase. J Clin Endocrinol Metab 86:888–894 8. Holmes VA, Barnes MS, Alexander HD, Mc Faul P, Wallace JM (2009) Vitamin D deficiency and insufficiency in pregnant women: a longitudinal study. Br J Nutr 102:876–881 9. Bodnar LM, Simhan HN, Powers RW, Frank MP, Cooperstein E, Roberts JM (2007) High prevalence of vitamin D insufficiency in black and white pregnant women residing in the northern US and their neonates. J Nutr 137:447–452 10. Lee JM, Smith JR, Philipp BL, Chen TC, Mathieu J, Holick MF (2007) Vitamin D deficiency in a healthy group of mothers and newborn infants. Clin Pediatr (Phila) 46:42–44
11. Bodnar LM, Catov JM, Simhan HN, Holick MF, Powers RW, Roberts JM (2007) Maternal vitamin D deficiency increases the risk of preeclampsia. J Clin Endocrinol Metab 92:3517–3522 12. Baker AM, Haeri S, Camargo CA, Espinola JA, Stuebe AM (2010) A nested case–control study of midgestation vitamin D deficiency and risk of severe preeclampsia. J Clin Endocrinol Metab 95:5105–5109 13. Brannon PM (2012) Vitamin D and adverse pregnancy outcomes: beyond bone health and growth. Proc Nutr Soc 71:205–212 14. Farrant HJ, Krishnaveni GV, Hill JC, Boucher BJ, Fisher DJ, Noonan K et al (2009) Vitamin D insufficiency is common in Indian mothers but is not associated with gestational diabetes or variation in newborn size. Eur J Clin Nutr 63:646–652 15. Sachan A, Gupta R, Das V, Agarwal A, Awasthi PK, Bhatia V (2005) High prevalence of vitamin D deficiency among pregnant women and their newborns in northern India. Am J Clin Nutr 81:1060–1064 16. Marya RK, Rathee S, Manrow M (1987) Effect of calcium and vitamin D supplementation on toxaemia of pregnancy. Gynecol Obstet Invest 24:38–42 17. American College of Obstetricians and Gynecologists (ACOG) Practice bulletin (2002) Diagnosis and management of preeclampsia and eclampsia. Obstet Gynecol 99(1):159–167 18. Holick MF, Binkley NC, Bischoff-Ferrari HA, Gordon CM, Hanley DA, Heaney RP et al (2011) Evaluation, treatment, and prevention of vitamin D deficiency: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab 96:1911–1930 19. Robinson CJ, Alanis MC, Wagner CL, Hollis BW, Johnson DD (2010) Plasma 25-hydroxyvitamin D levels in early -onset severe preeclampsia. Am J Obstet Gynecol 203:1–6 20. Olsen SF, Secher NJ (1990) A possible preventive effect of lowdose fish oil on early delivery and pre-eclampsia: indications from a 50-year-old controlled trial. Br J Nutr 64:599–609 21. Merewood A, Mehta SD, Chen TC, Bauchner H, Holick MF (2009) Association between vitamin D deficiency and primary cesarean section. J Clin Endocrinol Metab 94:940–945 22. Marya RK, Rathee S, Dua V, Sangwan K (1988) Effect of vitamin D supplementation during pregnancy on foetal growth. Indian J Med Res 88:488–492 23. Karim SA, Nusrat U, Aziz S (2011) Vitamin D deficiency in pregnant women and their newborns as seen at a tertiary-care center in Karachi, Pakistan. Int J Gynecol Obstet 112:59–62
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MATERNAL-FETAL MEDICINE
Relationship between preeclampsia and vitamin D deficiency: a case control study Rimpi Singla • Padma Gurung • Neelam Aggarwal Usha Dutta • Rakesh Kochhar
•
Received: 27 January 2014 / Accepted: 11 November 2014 Ó Springer-Verlag Berlin Heidelberg 2014
Abstract Purpose There is paucity of literature pertaining to association between vitamin D deficiency and preeclampsia from sunshine-rich countries like India. Further none of the studies have reported on relation with severity of preeclampsia. This study was carried out with a purpose of studying relation between vitamin D deficiency and preeclampsia and its complications. Methods Seventy-four nulliparous preeclamptic women with singleton pregnancy and without any known medical disorder and 100 healthy nulliparous controls of same age were enrolled. Serum vitamin D concentration of the two groups was compared. We also compared the vitamin D level of women with mild and severe preeclampsia and with or without various complications of preeclampsia. Results Eighty-four percent of women were vitamin D deficient. Mean serum vitamin D was significantly lower among cases (9.7 ± 4.95 ng/ml) as compared to controls (14.8 ± 6.68 ng/ml); p = 0.0001. Women with mild preeclampsia (9.44 ± 5.63 ng/ml) had similar vitamin D level as those with severe disease (9.8 ± 4.79 ng/ml) (p = 0.811). There was no difference in vitamin D level of women with eclampsia (p = 0.956) or imminent eclampsia (p = 0.310) and those without these complications. Conclusion There is high prevalence of vitamin D deficiency among pregnant women in India. Women with R. Singla P. Gurung N. Aggarwal (&) Department of Obstetrics and Gynecology, Post Graduate Institute of Medical Education and Research, Chandigarh, India e-mail: [email protected]; [email protected] U. Dutta R. Kochhar Department of Gastroenterology, Post Graduate Institute of Medical Education and Research, Chandigarh, India
preeclampsia had significantly lower vitamin D level as compared to normal women. Severity of the disease was not related to vitamin D level. Keywords Pregnancy
Preeclampsia Vitamin D deficiency
Introduction Preeclampsia is a pregnancy-specific syndrome characterized by hypertension and proteinuria, affecting approximately 2–10 % of pregnancies [1–3] and is the major cause of maternal and fetal morbidity and mortality worldwide [1, 3]. It contributes to major proportion of maternal deaths, up to 16 % in developed countries [4]. Various risk factors and preventive methods have been tested [1]. Still there are no definite preventive measures. Pathogenesis of preeclampsia is believed to involve maternal immune rejection of the placental cytotrophoblasts leading to inadequate remodeling and trophoblastic invasion of spiral arteries leading to shallow implantation and hypoxia and release of inflammatory mediators [5]. With the recognition of immunomodulatory properties of vitamin D, the role of this secosteroid hormone in normal placentation had been the subject of recent research. Vitamin D receptors [6] and 1-a hydroxylase [7] are expressed both in decidua and trophoblast cells, providing an evidence for role of vitamin D in placentation. Vitamin D deficiency has been widely reported among pregnant women in various countries [8–10]. Some studies have shown association between vitamin D deficiency (VDD) and preeclampsia [11, 12] and other adverse pregnancy outcomes [13]. Most of the studies are from countries situated in different latitudes generally away from equator. Vitamin D deficiency is also prevalent among
123
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pregnant women in India despite sunny climate and proximity to equator [14, 15]. Lack of sun exposure, skin pigmentation and dietary insufficiency are the main reasons. There is paucity of literature pertaining to association between VDD and preeclampsia from sun-rich country of India and the available studies are quite old [16]. None of the studies from India to the best of our knowledge have tried to find relation with severity of preeclampsia. Since preeclampsia contributes to 9 % of maternal deaths in India [4], finding relation with vitamin D deficiency may lead us to a non-expensive preventive measure. This would have widespread maternal health implications as so far we do not have definitive preventive measures. So, this study was conducted to study the prevalence of vitamin D deficiency and its relationship with preeclampsia and with the disease severity.
Materials and methods This case control study was conducted over a period of 18 months in a tertiary care referral institute in Northern India. A total of 71 pregnant preeclamptic women were recruited for this study after assessing their eligibility according to the selection criteria. Inclusion criteria were nulliparous preeclamptic women with live singleton pregnancy. Preeclampsia was defined as systolic blood pressure C140 mmHg and/or a diastolic pressure C90 mmHg, measured at separate occasions at least 4 h apart and proteinuria in a 24-h protein excretion C300 mg or 1? on random urine sample [17]. Severe preeclampsia was defined as systolic blood pressure C160 mmHg and/or diastolic pressure C110 mmHg and/or proteinuria in a 24-h protein excretion C5 gms or 3? on random urine sample. Associated symptoms and abnormal investigations like cerebral dysfunction (blurred vision, scotoma, headache, cerebrovascular accidents), epigastric or right upper quadrant pain, renal failure or oliguria B500 ml in 24 h, impaired liver function (serum transaminase levels two times normal or greater), thrombocytopenia 3 (B100,000 platelets/mm ), fetal growth restriction, HELLP (hemolysis, elevated liver enzymes, low platelets), coagulopathy, pulmonary edema, eclampsia (generalized convulsions) were also recorded. Women with preexisting medical conditions like rheumatoid arthritis, thyroid, hepatic or renal failure, metabolic bone disease, diabetes mellitus, malabsorption, chronic hypertension and lupus, or with multiple pregnancy, or history of intake of medications influencing bone, vitamin D or calcium metabolism e.g. Antiepileptic/theophylline/antitubercular drugs in the last 6 months were excluded. One hundred and three healthy nulliparous pregnant women with singleton pregnancy and no associated morbidity were recruited as
123
controls from the same region in the same time frame. Written informed consent was obtained from all the women. Out of 103 controls, 3 eventually developed mild preeclampsia and so were taken up as cases. Relevant details like age, education, occupation, and socio-demographic factors were noted on a predesigned Performa. Blood sample for vitamin D level as well as serum calcium and alkaline phosphatase was collected at enrollment and immediately transported to the laboratory. Serum was separated by centrifugation and stored at 20 °C and analyzed by ELISA method (Immune Diagnostic Systems, UK). Deficiency was defined as serum level of \20 ng/ml, insufficiency as 20–30 ng/ml and optimum level as [30 ng/ml [18]. All the subjects were managed as per protocol of the institute. During the course of her pregnancy if the subject in control group developed preeclampsia then she was excluded from the control group and taken up as case. The study was approved by institute’s ethics committee and was performed in accordance with the ethics standards as laid down in Declaration of Helsinki. Primarily, we looked for difference in vitamin D status of preeclamptic women as compared to the controls. Further we looked for any relation between severity of preeclampsia, its complications and mode of delivery with vitamin D status. Secondarily, we studied the fetal outcomes as birth weight, stillbirth, neonatal complications, admission to neonatal intensive care unit (NICU) or neonatal nursery (NNN). The data were analyzed using SPSS version 17. Appropriate statistical tests were used as applicable. A ‘p’ value of B0.05 was considered significant.
Results Mean age in the preeclampsia (case) group was 25.22 ± 3.08 years and in the control group was 25.11 ± 3.12 years; the difference was not significant (p = 0.6). The mean gestation of cases was 34.5 ± 3.1 weeks and that in the controls was 35.8 ± 2.2 weeks. All the women were from same city or neighboring states living in within the latitudes of 30–32°N. The prevalence of vitamin D deficiency (vitamin D \20 ng/ml) in entire study population was 83.9 %. Only one woman that was in the control group had sufficient vitamin D level of [30 ng/ml. Mean systolic and diastolic blood pressure of cases were 156 ± 19.5 and 104 ± 10.5 mmHg while that of control group were 117 ± 4.7 and 75 ± 5.2 mmHg. Mean serum vitamin D was significantly lower among the cases (9.7 ± 4.95 ng/ml) compared to that of the controls (14.8 ± 6.68 ng/ml); p = 0.0001 (Table 1). Significantly higher proportion of subjects among the cases (93.2 %) were vitamin D deficient in comparison to the controls
Arch Gynecol Obstet Table 1 Vitamin D status of women with preeclampsia and various complications Vitamin D level (mean ± SD) ng/ml
P value
Table 2 Maternal and fetal outcome in vitamin D deficient preeclamptic patients Parameter
Vitamin D\20 ng/ ml (n = 69)
0.0001*
Vitamin D [20 ng/ml (n = 5)
p value
Cases (n = 74)
9.7 ± 4.95
Controls (100)
14.8 ± 6.68
Mild preeclampsia (17) Severe preeclampsia (57)
9.44 ± 5.63 9.80 ± 4.79
0.811
Imminent eclampsia Present (16)
8.82 ± 2.54
0.310
Absent (58)
9.81 ± 5.43
Normal
Present (7)
9.62 ± 4.46
Absent (67)
9.73 ± 5.03
Cesarean section Forceps
5 (100 %)
0 (0 %)
Eclampsia
*
0.012
Normal vaginal (41)
11.21 ± 5.70
Cesarean section (28)
8.06 ± 3.18
Condition at birth Live born (70) Still born (4)
0.559 9.81 ± 4.81 8.46 ± 7.27 0.905
Present (35)
10.04 ± 5.29
Absent (35)
9.89 ± 4.66
Sepsis
0.921
Present (20)
9.87 ± 4.22
Absent (50)
10.0 ± 5.25
Admission to NICU/NNN
16 (100 %)
0
0.215
Eclampsia
7 (100 %)
0
0.454
36 (52.2 %)
5 (100 %)
0.116
28 (100 %)
0 (0 %)
Neonatal outcomea
6.8 ± 1.46
NNJ
Imminent eclampsia
Mode of delivery (n/74)
0.956
Mode of delivery
Forceps (5)
Complications (n/74)
HIE
3/66
0/4
0.623
IVH
2/66
0/4
0.691
NNJ
32/66
3/4
0.643
Sepsis
19/66
1/4
0.660
Admission to NICU/NNN
25/66
1/4
0.410
Neonatal mortality
9/66
1/4
0.705
HIE Hypoxic ischemic encephalopathy, IVH intraventricular hemorrhage, NNJ neonatal jaundice, NICU neonatal intensive care unit, NNN neonatal nursery a
Livebirths
0.322
Present (26)
9.2 ± 4.02
Absent (44)
10.4 ± 5.41
NNJ neoanatal jaundice, NICU neonatal intensive care unit, NNN Neonatal nursery * p value of \0.05 is significant
(78 %); p = 0.006. Vitamin D concentration showed negative correlation with both systolic (r = -0.370; p = 0.001) and diastolic blood pressure (r = -0.387; p = 0.001). Out of 74 cases, 17 (23 %) had mild preeclampsia and 57 (77 %) had severe form of preeclampsia. Mean vitamin D level of women with mild preeclampsia and those with severe disease was similar (p = 0.811) (Table 1). Sixteen subjects had imminent eclampsia. Though mean vitamin D concentration did not differ with presence or absence of imminent eclampsia (p = 0.310), none of the subjects with vitamin D level of [20 ng/ml had this complication (Table 2). Also, mean value among women with or without eclampsia was similar but all of the seven women who had eclampsia were vitamin D deficient (\20 ng/ml) (Table 2). Among the cases, vitamin D level of patients requiring cesarean section was significantly lower than those having normal vaginal delivery (p = 0.022). The main
indication of cesarean section among cases was fetal distress (in 20 women) and abruptio placentae (in 5 women). For the entire study population of 174 subjects also, vitamin D level in women undergoing cesarean was significantly lesser than vaginal delivery (10.71 ± 6.32 vs. 13.45 ± 6.45 ng/ml; p = 0.013). Birth weight showed positive correlation with the vitamin D concentration (r = 0.245; p = 0.001). Gestational age at delivery had direct correlation with vitamin D concentration (r = 0.313; p = 0.001). No difference was observed between vitamin D levels of mothers whose babies suffered with various neonatal complications. Mean vitamin D level of rural women (11.40 ± 6.59 ng/ml) was significantly lesser than urban women (13.42 ± 6.38 ng/ml); p = 0.05. Vitamin D concentration had positive correlation with serum calcium (r = 0.245; p = 0.05) but no relation to alkaline phosphatase (r = 0.023; p = 0.848).
Discussion Preeclampsia is associated with high maternal and fetal morbidity and mortality [4]. Recent research has pointed towards some role of vitamin D deficiency in pathogenesis
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of preeclampsia. While we have a fair number of studies from developed countries, but very few investigators have studied the relation between vitamin D deficiency and preeclampsia from India. First of all, our study showed alarmingly high prevalence of vitamin D deficiency among pregnant women. Nearly, 84 % of the women were deficient and rest of them mostly had insufficient levels. The reasons may be lack of sun exposure and fortification of food with vitamin D, and irregular intake of prenatal vitamins. Urban women had better vitamin D status than rural women; this may be due to more of outdoor activity in urban women than their rural counterparts during pregnancy. Though direct comparisons between studies are not possible due to inconsistent definitions of deficiency and insufficiency [8–10], most of them including the present one show high prevalence of preeclampsia among vitamin D deficient women. In previous studies deficiency was defined as serum level of less than 15 ng/ml but now, based on array of some biomarkers, it has been recognized that minimum serum concentration of 20 ng/ml is desirable. Hence, deficiency is now defined as serum level of \20 ng/ml [18]. We found significant association between vitamin D deficiency and preeclampsia. Lower serum concentration among preeclamptic women signifies the underlying role of vitamin D deficiency in pathogenesis of the disease. Women in the control group had similar age, same parity (all nulliparous), belonged to same geographical area and were recruited in same time frame as cases, hence eliminating most of the confounding factors. Bodnar et al. [10] found a fivefold increase in the odds of preeclampsia with early pregnancy vitamin D level of less than 37.5 nmol/ liter (15 ng/ml). Similarly, in another study, subjects with early onset severe preeclampsia were noted to have decreased total vitamin D levels relative to healthy controls (18 vs. 32 ng/mL, p \ 0.001) [19]. One clinical trial addressing role of vitamin D in preventing preeclampsia supports a potential role of vitamin D in the prevention of preeclampsia. It reported that supplementation with a multivitamin/mineral supplement and halibut liver oil (containing 900 IU/d vitamin D) provided at 20 week gestation reduced the odds of preeclampsia by 32 % [20], Another study randomized 400 women at 20–24 week gestation to vitamin D (1200 IU/d) and calcium (375 mg/d) supplements or no treatment and found non-significant reduction in the incidence of preeclampsia in the treated group compared with the untreated (6 vs. 9 %) [16]. None of the above trials used vitamin D alone, hence exact role in prevention cannot be commented up on. We did not find significant difference in vitamin D level between mild and severe disease. Though all our patients who developed imminent eclampsia or eclampsia had vitamin D level of \20 ng/ml approaching at a definite
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conclusion is not feasible as most of the patients were vitamin D deficient only. Mean serum levels among the women with or without imminent eclampsia or eclampsia were not significantly different. This suggests that vitamin D has preventive role, and once preeclampsia sets in it may not be effective altering the course or controlling the severity. After the onset of disease, woman’s own system i.e. the level of oxidative stress, inflammatory mediators, vascular endothelial damage, immune responses etc. dictates the course. Mode of delivery was affected by vitamin D status as all of the women from disease group requiring cesarean section or forceps delivery were vitamin D deficient. Serum vitamin D concentration of women with preeclampsia requiring cesarean section (all were primary cesareans) was significantly lower than that of women having normal delivery. Results remained significantly different in the similar fashion for the entire study population of 174 women. Similar result was seen in a study by Merewood et al.; there was an inverse association with having a cesarean section and serum vitamin D levels. Women with 25(OH) D concentrations \37.5 nmol/L were four times more likely to have a cesarean delivery than women with vitamin D concentrations [37.5 nmol/L [21]. All the women undergoing forceps delivery had severe deficiency (serum vitamin D level of less than 10 ng/ml); this may be associated with poor muscle function. Most important reasons for forceps application were prolonged second stage and fetal bradycardia. Birth weight showed positive correlation with vitamin D level. So far many studies have reported association between low birth weight and vitamin D deficiency. Marya et al. [22] from India, reported higher body weight, crown heel length, head circumference and mid arm circumference in mothers who received two doses of 6,00,000 IU of vitamin D3 during third trimester pregnancy compared to those who did not receive vitamin D. Maternal vitamin D deficiency is also associated with low serum vitamin D levels in the newborn [10, 15, 23]. Overall preeclampsia was associated with significant maternal and fetal morbidity. There were four still births in the disease group. Newborns of preeclamptic women had significant morbidity in the form of sepsis, jaundice, hypoxic ischemic encephalopathy (HIE) and admission to NICU mainly due to premature inductions in maternal interest. Mothers whose neonates faced various neonatal complications had no difference in their vitamin D status as compared to those without respective complication. So, we found high prevalence of hypovitaminosis D among pregnant women in India. Women with preeclampsia had significantly lower vitamin D level as compared to normal women, suggesting its role in pathogenesis of preeclampsia. Severity of the disease was not
Arch Gynecol Obstet
related to vitamin D level. There was high incidence of cesarean delivery among vitamin D deficient women. Birth weight showed improvement with vitamin D status. Overall, vitamin D deficiency was found to be related to adverse maternal and fetal outcome. Conflict of interest We report no financial relation with any organization. We declare that authors have full control of the primary data. The authors declare that they have no conflict of interest.
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