By Sabour, Hadis; Hossein-Nezhad, Arash; Maghbooli, Zhila; Madani, Farzaneh; Et al
Abstract
Poor maternal vitamin D status affects fetal and infant skeletal growth. The aim of the present study was to determine the association between newborn outcomes and maternal calcium and vitamin D intakes. Four hundred and forty-nine pregnant women, healthy at the point of delivery, and their newborns were enrolled in the study, which was performed in three university hospitals in Tehran in March 2004. Maternal anthropometric data and energy, protein, calcium and vitamin D intakes were collected, and newborn outcomes (weight, length, head circumference and 1-min Apgar score) were determined. Almost two-thirds of the mothers (64.3%) took no supplements during pregnancy. Only one-third of the mothers (33.8%) had adequate intakes of calcium and vitamin D (from supplements and foods) compared with the Recommended Dietary Allowances. Mean length at birth and 1-min Apgar score were higher in newborns whose mothers had adequate calcium and vitamin D intake than in newborns whose mothers had inadequate intake (p = 0.03 and p = 0.04, respectively). Significant correlations were found between adequate maternal calcium and vitamin D intake and both appropriate birth weight and 1- min Apgar score of newborns and weight gain of mothers during pregnancy. Informing mothers of the critical importance of consuming adequate amounts of calcium and vitamin D seems necessary.
Keywords: Pregnancy, calcium, vitamin D, intake, outcome
Introduction
Vitamin D is a steroid hormone that is essential for calcium homeostasis and maintenance of bone health [1]. Poor vitamin D status may lead to a decrease in serum calcium, resulting in an increase in parathyroid hormone concentration which can increase bone turnover and decrease bone mineral accretion [2]. Changes in maternal bone turnover during pregnancy may affect fetal bone mineral content. These changes are consistent with corresponding blood biochemistry changes; increased bone resorption markers in the first trimester, while bone formation markers increase in the last trimester [3].
Studies carried out in the preceding two decades have shown a high prevalence of vitamin D deficiency in many countries and revealed the prevalence of vitamin D deficiency to be higher in women than in men [4-10]. Two studies in Iran demonstrated that the prevalence of vitamin D deficiency in Tehran was between 9.5 and 57.6% [4,11]. Most studies have included women at high risk of vitamin D deficiency because of low vitamin D and calcium intakes or decreased ability to synthesize endogenous vitamin D (attributable to a lack of sun exposure).
Vitamin D deficiency is also a serious problem during pregnancy. Overall vitamin D supplementation in the pregnant populations leads to improved neonatal handling of calcium [1,3,12-16] and improved gain of infant weight [17]. In countries where dairy products are not routinely supplemented with vitamin D or where sun exposure is low due to geographical location (northern countries) or religious beliefs, vitamin D should be administered to the mother during pregnancy or to new infants just after birth [17]. If dietary vitamin D supplementation throughout pregnancy can be undertaken, the amount given should be 400 IU/day (10 g/day). In countries where, in addition, presentation for antenatal care is delayed, 1000 IU/day (25 g/day) should be given during the last trimester of pregnancy or 100 000 IU/day (2500 g/day) in one dose at the beginning of the last trimester [17].
The aim of the present study was to determine the association between pregnancy outcomes and maternal calcium and vitamin D intakes in Iran.
Methods
Four hundred and forty-nine pregnant women, healthy at the point of delivery, and their newborns were enrolled in the study. The study was performed in three university hospitals affiliated to the Tehran University of Medical Sciences in March 2004. The study protocol was approved by the research ethics committee of the Endocrinology & Metabolism Research Center and informed consent was obtained from each participant before enrollment. All of the pregnant women met our inclusion criteria: i.e. no history of taking any kind of drug that could interact with calcium and vitamin D metabolism and the absence of chronic diseases.
Maternal anthropometric data, general health status, drug history and weight gain pattern were all recorded. Standing height was measured using a portable stadiometer with 0.1 cm precision. Weight was measured using scales with precision of 0.1 kg. Pre-pregnancy body mass index (BMI) was calculated and classified according to World Health Organization/Food and Agriculture Organization guidelines. Dietary data were obtained using a food-frequency questionnaire validated by the nutrition group of the Endocrinology & Metabolism Research Center. Mean energy and nutrient intakes were calculated and compared with the Recommended Dietary Allowances (RDA, 2004) for pregnant women [18]. Based on calcium and vitamin D intake, pregnant women were divided into two groups: those with adequate intake and those with inadequate intake.
For each newborn, weight, length and head circumference were measured, and 1-min Apgar score was determined [19]. Low birth weight (LBW) was denned as birth weight lower than 2500 g [19].
Maternal weight gain pattern during pregnancy, and weight, length, head circumference and Apgar score of the newborns were compared between the groups with adequate and inadequate calcium and vitamin D nutritional status. Comparisons between groups were made using Student’s t test and the frequency of variables was compared with the ?2 test. Pearson’s correlation was used to investigate correlations between variables, and linear regression and univariate models were used to determine any relationships between variables. Statistical analyses were conducted using SPSS software, version 11.5 (SPSS Inc., Chicago, IL, USA).
Results
The mean energy and nutrient intakes of the pregnant mothers are classified in Table I. The mean daily intake of vitamin D was 2.26 1.87 g and the mean daily intake of calcium was 816.28 370.47 mg ( standard deviation, SD). About half of the mothers (47.2%) had adequate energy intake based on the current RDA for pregnant women. One in six mothers (16.7%) had adequate intake of calcium and about one in four (26.7%) had adequate intake of vitamin D, based on the current RDA for pregnant women, from natural sources. About two- thirds of mothers (64.3%) did not take supplements in pregnancy; the rest took calcium and vitamin D supplements during pregnancy. Only one-third of mothers (33.8%) received adequate calcium and vitamin D (from supplements and foods) compared with the RDA.
Anthropometric characteristics of the mothers and newborn birth outcomes are presented in Table II. Mean (SD) values for mothers were 62.20 12.18kg for weight, 160.4 5.6 cm for height and 24.2 5.0 kg/m^sup 2^ for BMI. Fifty-three percent of the newborns were boys. In total, 5.2% of the newborns were LBW and 2.9% of them had 1- min Apgar score
Table I. Mean intakes and supplement use of pregnant mothers.
Table II. Anthropometric characteristics of the mothers and birth outcomes of newborns.
Newborn outcomes according to maternal calcium and vitamin D intake are compared in Table III. Mean length and 1-min Apgar score were significantly higher in newborns whose mothers had adequate calcium and vitamin D intake than in newborns whose mothers had inadequate intake (p = 0.03 and p = 0.04, respectively). There was no significant association between head circumference or birth weight and maternal calcium and vitamin D intake. The incidence of LBW was significantly lower in newborns with adequate maternal calcium and vitamin D intake (p = 0.007). A significant correlation existed between higher maternal weight gain and adequate intake of calcium and vitamin D. Moreover, mothers with pre-pregnancy BMI
Discussion
Concerns about vitamin D have resurfaced in the medical and scientific literature because the prevalence of vitamin D deficiency has increased in many countries [1,20,21]. The findings of numerous studies suggest that the prevalence of clinical and subclinical vitamin D deficiency is higher in pregnant women. This is due to the fetus being wholly dependent on maternal circulating 25- hydroxyvitamin D [20-24].
Generally, it seems that overall intakes of calcium and vitamin D are not sufficient in our country. Of the pregnant women studied in the present investigation, only 16.7% received adequate calcium intake and only 26.7% received adequate vitamin D intake from foods.
The mean daily dietary vitamin D intake of Pakistani women was 1.05 0.80 g [22]; in another study, Pakistani women were found to consume 793 mg calcium daily [23]. Calcium status evaluation in Austria confirmed that the average intake was 834 422 mg/day [25]. Different international studies in Saudi Arabia, Finland, Turkey and Spain illustrated insufficient vitamin D in pregnant women’s diets [14,26-28]. Similarly, a \study in Venezuela concluded that a high proportion of pregnant women do not take the recommended amounts of calcium [29]. The average daily calcium intake for pregnant women has been estimated at 300-1000 mg/day [1].
Table III. Comparison of birth outcomes of newborns according to adequacy of maternal calcium and vitamin D intakes*.
All of these studies confirm our results that dietary intakes of calcium and vitamin D are extremely low [3]. Vitamin D supplements have been recommended, to cope with fetal demands [30-33]. In our study only 35.7% of the women had taken calcium and vitamin D supplements. However, other investigations have also indicated the poor usage of supplements elsewhere [23,26,27]. For example, only 70% of pregnant women in Finland used vitamin D supplements [26] and none of the pregnant women in a study in Pakistan used supplemental vitamin D during pregnancy [23].
We found that adequate intake of calcium and vitamin D from both foods and supplements produced higher length at birth and better Apgar score. Other studies confirm this finding [1,20,34,35]. We also found a significant correlation between adequate maternal intake of calcium and vitamin D and appropriate birth weight. We did not find any significant correlation between head circumference of the newborn and calcium/vitamin D intake of the mother, in agreement with previous results [36]. Our mothers with pre-pregnancy BMI
A majority of pregnant women are unaware of the effect of these nutrients on their own health and pregnancy outcomes, and do not consume sufficient quantities to meet the RDA. Synthesis of vitamin D in the skin is insufficient to meet daily needs. Moreover there are few food sources with an adequate content of natural vitamin D. The current adult recommendation for daily vitamin D intake from the Food and Nutrition Board is 200 IU up to age 50 years, 400 IU up to age 70 years, and 600 IU thereafter [38]. However, it now appears that, if total input were confined to these amounts, only the most severe degrees of vitamin D deficiency would be prevented and recent dietary recommendations for adults are not sufficient to maintain circulating 25-hydroxyvitamin D at or above this level, especially in pregnancy and lactation. This deficiency cut-off is now based on an array of biomarkers that are adversely affected by nutritional vitamin D deficiency rather than on Gaussian distributions of 25- hydroxyvitamin D concentrations in populations, as were used in the past [38]. We should now consider this deficiency to occur at circulating 25-hydroxyvitamin D levels
The results of the present study highlight the critical role of vitamin D in pregnancy outcomes. Thus adults and especially pregnant women should be informed of suitable food sources and those with deficiencies should be recommended to take correct supplementary amounts to meet their bodily needs. A countrywide targeted public education for women with the purpose of improving the health of mothers and babies should be initiated.
Some limitations of our study should be mentioned. First, all of the women studied had low socioeconomic status, and the pattern of nutrition could be different for women with higher socioeconomic status. Second, the study was performed in university hospitals and further work is needed to enable implementation in general or private centers. Third, use of a food-frequency questionnaire was required to evaluate the intakes of calcium and vitamin D from food accurately. Finally, the associations found may have been stronger if the study had been designed as a cohort or randomized clinical trial, and any future work should consider the role of other nutrients as confounding or interacting factors.
References
1. Thomson K, Morley R, Grover SR, Zacharin MR. Postnatal evaluation of vitamin D and bone health in women who were vitamin D- deficient in pregnancy, and in their infants. Med J Aust 2004;181:486-488.
2. Specker B. Nutrition influences bone development from infancy through toddler years. J Nutr 2004;134:6918-6955.
3. Prentice A. Micronutrients and the bone mineral content of the mother, fetus and newborn. J Nutr 2003;133:81693-51699.
4. Hashemipour S, Larijani B, Adibi H, Javadi E, Sedaghat M, Pajouhi M, Soltani A, Shafaei AR, Hamidi Z, Fard AR, et al. Vitamin D deficiency and causative factors in the population of Tehran. BMC Public Health 2004;4:38.
5. Holvic K, Meyer HE, Haug H, Brunvand L. Prevalence and predictors of vitamin D deficiency in five immigrant groups living in Oslo, Norway: the Oslo Immigrant Health Study. Eur J Clin Nutr 2005;59:57-63.
6. Advani S, Wimalawansa SJ. Bones and nutrition: common sense supplementation for osteoporosis. Curr Womens Health Rep 2000;3:187- 192.
7. Glowacki J, Hurwitz S, Thomhill TS, Kelly M, LeBoff MS. Osteoporosis and vitamin-D deficiency among postmenopausal women with osteoarthritis undergoing total hip arthroplasty. J Bone Joint Surg Am 2003;85A:2371-2377.
8. Meyer HE, Falch JA, Soggard AJ, Haug E. Vitamin D deficiency and secondary hyperparathyroidism and the association with bone mineral density in persons with Pakistani and Norwegian background living in Oslo, Norway, The Oslo Health Study. Bone 2004;35:412- 417.
9. Passen G, Pini G, Troiano L, Vescovini R, Sansoni P, Passeri M, Gueresi P, Delsignore R, Pedrazzoni M, Franceschi C. Low vitamin D status, high bone turnover, and bone fractures in centenarians. J Clin Endocinol Metab 2003;88:5109-5115.
10. Rahman SA, Chee WS, Yassin Z, Chan SP. Vitamin D status among postmenopausal Malaysian women. Asia Pacific J Clin Nutr 2004;13:255- 260.
11. Bassir M, Laborie S, Lapillonne A, Claris O, Chappuis MC, Salle BL. Vitamin D deficiency in Iranian mothers and their neonates: a pilot study. Acta Paediatr 2001;90:577-579.
12. Specker B. Vitamin D requirements during pregnancy. Am J Clin Nutr 2004;80:S1740-S1744.
13. Oliven MB, Mautalen CA, Alonso A, Velazquez H, Trouchot HA, Porto R, Martinez L, Barata AD. [Nutritional status of vitamin D in mothers and neonates of Ushuaia and Buenos Aires]. Medicina (B Aires) 1993;53:315-320.
14. Serenius F, Elidrissy AT, Dandona P. Vitamin D nutrition in pregnant women at term and in newly born babies in Saudi Arabia. J Clin Pathol 1984;37:444-447.
15. Flynn A. The role of dietary calcium in bone health. Proc Nutr Soc 2003;62:851-858.
16. Nowson CA, Margerison C. Vitamin D intake and vitamin D status of Australians. Med J Aust 2002;177:149-152.
17. Salle BL, Delvin EE, Lapillonne A, Bishop NJ, Glorieux FH. Perinatal metabolism of vitamin D. Am J Clin Nutr 2000; 71:13175- 13248.
18. Mahan KL. Food, nutrition & diet therapy. Philadelphia (PA): WB Saunders; 2004.
19. Cunningham FG, McDonald PC, Gant NF, Leveno KJ, Gilstrap LC, Hankins GDV, Clark SL. editors. Williams’ obstetrics. Stamford (CA): Appleton & Lange;1997.
20. Hollis BW, Wagner CL. Assessment of dietary vitamin D requirements during pregnancy and lactation. Am J Clin Nutr 2004;79:717-726.
21. Nozza JM, Rodda CP. Vitamin D deficiency in mothers of infants with rickets. Med J Aust 2001;175:253-255.
22. Alfaham M, Woodhead S, Pask G, Davies D. Vitamin D deficiency: a concern in pregnant Asian women. Br J Nutr 1995;73:881- 887.
23. Atiq M, Suria A, Nizami SQ, Ahmed I. Maternal vitamin-D deficiency in Pakistan. Acta Obstet Gynecol Scand 1998;77: 970-973.
24. Fogelman Y, Rakover Y, Luboshitzky R. High prevalence of vitamin D deficiency among Ethiopian women immigrants to Israel: exacerbation during pregnancy and lactation. Isr J Med Sci 1995;31:221-224.
25. Koenig J, Elmadfa I. Status of calcium and vitamin D of different population groups in Austria. Int J Vitam Nutr Res 2000;70:214-220.
26. Erkkola M, Karppinen M, Jarvinen A, Knip M, Virtanen SM. Folate, vitamin D, and iron intakes are low among pregnant Finnish women. Eur J Clin Nutr 1998;52:742-748.
27. Pehlivan I, Hatun S, Aydogan M, Babaoglu K, Gokalp AS. Maternal vitamin D deficiency and vitamin D supplementation in healthy infants. Turk J Pediatr 2003;45:315-320.
28. Ortega RM, Aranceta J, Serra-Majem L, Entrala A, Gil A, Mena MC. Nutritional risks in the Spanish population: results of the eVe study. Eur J Clin Nutr 2003;57:S73-S75.
29. Pena E, Sanchez A, Portillo Z, Solano L. Dietary evaluation of pregnant adolescents during first, second and third trimester. Arch Latinoam Nutr 2003;53:133-140.
30. Salle BL, Delvin E, Glorieux F. Vitamin D and pregnancy. Bull Acad Natl Med 2002;186:369-376.
31. Hatun S, Ozkan B, Orbak Z, Doneray H, Cizmecioglu F, Toprak D, Calikoglu AS. Vitamin D deficiency in early infancy. J Nutr 2005; 135:279-282.
32. Committee on Medical Aspects of Food and Nutrition Policy, Panel on Child and Maternal Nutrition. Scientific review of the welfare food scheme. Report on health and social subjects no. 51. London: The Stationery Office; 2002.
33. Nesby-O’Dell S, Scanlon KS, Cogswell ME, Gillespie C, Hollis BW, Looker AC, Alien C, Doughertly C, Gunter EW, Bowman BA. Hypovitaminosis D prevalence and determinants among African American and white women of reproductive age: third National Health and Nutrition Examination Survey, 1988-1994. Am J Clin Nutr 2002;76:187- 192.
34. Ancri G, Morse EH, Clarke RP. Comparison of the nutritional status of pregnant adolescents with adult pregnant women. III. Maternal protein and calorie intake and weight gain in relation to size of infant at birth. Am J Clin Nutr 1977;30:568-572.
35. An H, Yin S, Xu Q. Effects of supplementing calcium, iron and zinc on the fetus development and growth during pregnancy. Zhonghua Yu Fang Yi Xue Za Zhi 2001;35: 370-373.
36. Boutaleb Y, Lahlou N, Oudghiri A, Mesbahi M. Birth weight in an African country. J Gynecol Obstet Biol Reprod 1982; \11:68-72.
37. Ravindra C. Correlation between adolescent nutrition during pregnancy and outcome of low birth-weight babies. J FIa Med Assoc 1989;76:523-525.
38. Armas LA, Mollis BW, Heaney RP. Vitamin D^sub 2^ is much less effective than vitamin D^sub 3^ in humans. J CHn Endocrinol Metab 2004;89:5387-5391.
39. Hollis BW. Circulating 25-hydroxyvitamin D levels indicative of vitamin D sufficiency: implications for establishing a new effective dietary intake recommendation for vitamin D. J Nutr 2005;135:317-322.
40. Hollis BW, Wagner CL. Vitamin D deficiency during pregnancy: an ongoing epidemic. Am J Clin Nutr 2006;84:273.
41. Dawson-Hughes B, Heaney RP, Holick MF, Lips P, Meunier PJ, Vieth R. Vitamin D round table. In: Burckhardt P, Dawson-Hughes B, Heaney R, editors. Nutritional aspects of osteoporosis. 2nd ed. Burlington (MA): Elsevier Science and Technology Books; 2004. pp 263- 270.
HADIS SABOUR, ARASH HOSSEIN-NEZHAD, ZHILA MAGHBOOLI, FARZANEH MADANI, ELHAM MIR, & BAGHER LARIJANI
Endocrinology & Metabolism Research Center, Tehran University of Medical Sciences, Tehran, Iran
(Received 22 March 2006; revised 20 August 2006; accepted 8 September 2006)
Correspondence: B. Larijani, Endocrinology & Metabolism Research Center, 5th floor, Shariati Hospital, North Kargar Avenue, Tehran, Iran.
Tel: 98 21 88026902/3. Fax: 98 21 88029399. E-mail: [email protected]
Copyright Taylor & Francis Ltd. Oct 2006
(c) 2006 Gynecological Endocrinology. Provided by ProQuest Information and Learning. All rights Reserved.
Comments