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Center for Human Nutrition, Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, and * Nepal Nutrition Intervention Project-Sarlahi (NNIPS), Nepal Netra Jyoti Sangh, Tripureswor, Kathmandu, Nepal
2To whom correspondence should be addressed. E-mail: pchristi{at}jhsph.edu.
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ABSTRACT |
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 TOP ABSTRACT SUBJECTS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
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20% of the women had 2, 3, or 4 deficiencies. Almost 18% of women had 
5 deficiencies. Micronutrient status varied by season; it was generally best during the winter months, except for serum vitamin D concentration, which peaked during the hot summer and monsoon months. Women in rural South Asia are likely to begin a pregnancy with multiple micronutrient deficiencies that may vary with seasonality in micronutrient-rich food availability.
KEY WORDS: • micronutrients • deficiency • season • pregnancy • Nepal
Micronutrient deficiency in women of reproductive age is recognized as a major public health problem in many developing countries (1–4). Pregnant women are particularly vulnerable to nutritional deficiencies because of the increased metabolic demands imposed by pregnancy involving a growing placenta, fetus, and maternal tissues, coupled with associated dietary risks (5,6). In turn, maternal undernutrition may predispose a mother to poor health, including infection, pre-eclampsia/eclampsia, and adverse pregnancy outcomes such as premature birth and intrauterine growth retardation (1,2). Micronutrient deficiencies tend to coexist in impoverished settings in part because of uniformly low consumption of foods rich in multiple micronutrients.
Maternal iron deficiency and consequent anemia comprise a major problem in developing countries, affecting >50% of women during pregnancy (1–3). Other micronutrient deficiencies are likely to be widely prevalent, especially those of iodine, zinc, vitamin A, and the vitamin B-complex (1–3,7). However, little information is available on the extent and severity of multiple micronutrient deficiencies during pregnancy in community-based studies (8,9). Most data on vitamin status are from select populations, hospital-based settings, or are from cross-sectional studies in which nutrient status was assessed at varying single time points during gestation. Because marginal micronutrient deficiency in the 1st trimester could lead to more severe deficiency later on due to stresses imposed by pregnancy and parturition (10), nutritional status in early pregnancy may be an important predictor of nutritional risk in late pregnancy (8). In addition, seasonality appears to markedly influence the prevalence of deficiency (7,11,12), which may sometimes result in unexpected patterns and interpretation of micronutrient deficiencies.
In previous studies, we documented a high prevalence of vitamin A and iron deficiency anemia among Nepali pregnant women (13–15) at various stages of pregnancy. In the present study, we investigated the prevalence of deficiency for vitamins A, E, D, riboflavin, B-6, B-12, folate, zinc, iron, and copper during early pregnancy (<12 wk) in a rural population of Nepalese pregnant women using published serological cutoff values. The coexistence of multiple deficiencies and seasonal variations in micronutrient status were also examined.
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SUBJECTS AND METHODS |
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TOPABSTRACTSUBJECTS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
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To identify pregnancies in early gestation, all eligible women of reproductive age (married women, 15–45 y of age who were not menopausal, sterilized, or not already breast-feeding an infant < 12 mo of age) in the study area were visited every 5 wk and monitored for pregnancy. Pregnancy was ascertained with a urine test (human chorionic gonadotrophin antigen test; Clue, Orchid Biomedical Systems) among women who had reportedly not menstruated in the past 30 d. Women who tested positive were enrolled after obtaining consent. At enrollment, newly identified pregnant women were administrated a baseline interview to obtain data on 1-wk frequencies of symptoms of morbidity, intake of food, alcohol, and tobacco use, and information on household socioeconomic status. Anthropometric measurements included weight, height and mid-upper arm circumference (MUAC)3 measurements.
Of 30 village development communities, comprising approximately one third of the total in the study area, 9 were selected to represent different geographic and ethnic communities; all had reasonable access to the main roads and relative proximity to the project laboratory. Women from these communities were invited to participate in a substudy involving venous blood collection for subsequent serum analysis of micronutrient status twice during pregnancy, before supplementation and in the third trimester. The samples were drawn via venipuncture and collected into 7-mL trace metal-free vacuum test tubes (Vacutainer, Becton Dickinson). The vacutainers containing blood were kept on ice and brought to the clinic where they were centrifuged at 750 x g for 20 min to separate the serum. Serum aliquots were placed into trace element–free cryotubes (Nalgene Company, Sybron International), stored in liquid nitrogen tanks, and shipped to the Johns Hopkins Bloomberg School of Public Health in Baltimore, MD, where they were stored at –80°C before analyses.
Laboratory analysis.
Hemoglobin (Hb) assessment was done on the spot using a homeglobinometer (HemoCue). Serum ferritin concentration was analyzed with ELISA procedures using a commercial fluoroimmunometric assay (DELFIA® Ferritin, Perkin Elmer Wallac). The interassay CV for ferritin was 5%, using pooled serum samples. Serum iron, zinc, and copper concentrations were analyzed by atomic absorption spectrometry (AAnalyst 600, Perkin Elmer). Serum folate was measured by a microbiological assay in 96-well microplates using a chloramphenicol-resistant strain of Lactobacillus rhamnosus (NCIMB 10463) (17). Serum vitamin B-12 was determined by a microbiological assay in 96-well microplates using a colistin-sulfate-resistant strain of Lactobacillus lactis (NCIMB 12519) (18,19). Both microorganisms were cryopreserved and the cultures were stable for many months. The interassay CVs for folate and vitamin B-12 were 7.6 and 8.4%, respectively. Serum 25-hydroxyvitamin D concentration was used to evaluate the vitamin D status, determined by an immunoassay method with kits from the Nichols Institute. The inter- and intra-assay CVs were 16.4 and 5.6%, respectively.
Serum retinol, ß-carotene, and 
-tocopherol were determined simultaneously by a reverse-phase HPLC (Beckman, System Gold) attached to an autosampler (717 Plus AS, Waters) using a procedure described by Yamini et al. (20) with modifications. The internal standard used was all-trans-ethyl-ß-apo-8'-carotenoate (Fluka Chem). The column (Allsphere ODS-2, 3 µm, 150 x 4.6 mm, Alltech Associate) was eluted isocratically with a mobile phase consisting of 84% acetonitrile, 14% tetrahydrofuran, 6% methanol (added 0.2% ammonium acetate), and 0.1% triethylamine. Quality control was maintained by repeated analyses of standard reference material (SRM, 968c, the National Institute of Standards and Technology, NIST, Gaithersburg, MD) and pooled reference standards. The precision and accuracy of the method were also assessed through participation in the Micronutrients Measurement Quality Assurance Program of Round Robin Proficiency Testing from the NIST, in which 12 "unknown" samples are analyzed and submitted yearly for the entire study period.
Serum riboflavin concentration was determined as a surrogate for riboflavin using reverse-phase HPLC (model 1100, Agilent Technologies) with a fluorescence detector (Model FP-1520, Jasco). Before HPLC, 50 µL of serum was deproteinized using trichloroacetic acid, and the supernatant was heated for 15 min. HPLC was performed using C18-coated silica column (Alltech) with a mobile phase consisted of 65% (v:v) 5 mmol/L ammonium acetate and 35% (v:v) methanol. Fluorescence excitation and emission wavelengths were 460 and 525 nm, respectively. The minimum detectable concentration was 0.35 nmol riboflavin/L. Intra- and interassay CVs were 1.5 and 4.8%, respectively, using pooled human serums. The serum concentration of pyridoxal 5'-phosphate, the active form of vitamin B-6, was measured using HPLC. The serum (100 µL) was deproteinized by the addition of perchloric acid. Precolumn derivatization was performed with potassium cyanide. The fluorescent cyanide derivatives were detected by fluorometry (Model FP-1520, Jasco) with wavelengths for excitation at 318 nm and for emission at 418 nm. The analytical HPLC column was an Alltech 3 µm ODS (C18), with a guard column packed with 40 µm C18 material (Alltech). The mobile phase was 50 mmol/L potassium phosphate buffer (pH 3.2) containing 50 mmol/L sodium perchlorate and mmol/L heptane sulfonic acid. The minimum detectable concentration was 2 nmol/L. Published cutoff values for defining deficient concentrations of micronutrients were used.
Statistical analysis. Descriptive statistical tests were applied to maternal biological, demographic and socioeconomic, and biochemical variables. Maternal age, gestational age at sample collection, BMI (calculated as kg/m2), and biochemical variables were treated as continuous variables, and diet and seasons were treated as categorical variables.
The proportion of women with deficient status was calculated for single and multiple micronutrients. We defined the 4 seasons as follows: Spring (March–May), Summer (June–August), Fall (September–November), and Winter (December–February). Univariate analyses were done to examine the association between season and micronutrient status. We performed step-wise multiple linear regression analyses to assess seasonal variation in micronutrient concentration using Spring as the reference season. Maternal age, gestational age, BMI, parity, tobacco and alcohol use, socioeconomic status, and ethnicity were adjusted in the model. The prevalence of micronutrient deficiency was determined for each season, and significant differences among the prevalence were assessed using 
2 analyses. The results were expressed as means ± SD, and a P-value of <0.05 was considered significant. Statistical analyses were performed using SAS software version 8.2 (SAS Institute).
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RESULTS |
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TOPABSTRACTSUBJECTS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
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Maternal age and gestational age at enrollment were 23.6 ± 6.0 y and 10.9 ± 4.6 wk, respectively; 26% of the women were nulliparous. The women were stunted with a height of 150.5 ± 5.5 cm; 14% were below the cutoff value of 145 cm (21). Subjects were also thin and wasted with a MUAC of 21.9 cm, and BMI of 19.3 kg/m2.
Serum micronutrient concentrations were normally distributed during early pregnancy except for riboflavin, vitamin B-12, folate, and ferritin, which were slightly skewed to the left (Table 1).
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60% of women, it was also the most frequent coexisting micronutrient deficiency (Table 2). Only 4% of women had no deficiency, whereas 14.3, 21.5, 20.6, 21.9, and 17.7 had 1, 2, 3, 4, or 5 or more deficiencies, respectively (data not shown). Women who were deficient in certain nutrients were more likely to have other micronutrient deficiencies (Table 3). For example, among the women with vitamin A deficiency, a higher proportion was deficient in vitamin E (70%), vitamin B-6 (52%), or riboflavin (44%) or were anemic (49%) relative to the overall prevalence of these in the population. The prevalence of micronutrient deficiencies differed by season (Table 4). Overall, most micronutrient deficiencies assessed tended to be less prevalent during the winter season. Serum retinol concentrations were significantly lower in the hot and humid monsoon season (April–September), whereas ß-carotene and vitamin B-6 concentrations were higher in summer and winter than in other seasons (Fig. 1). As expected, vitamin D levels were lowest in the winter months and highest in summer (June–August) and fall (September–November). Serum zinc concentrations were higher in fall and lower in summer. Multiple regression analysis also revealed that with the exception of vitamin D and copper, women had better micronutrient status during the winter months (December–February) than in the other seasons (data not shown).
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DISCUSSION |
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TOPABSTRACTSUBJECTS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
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The present study has several advantages over previous studies that examined micronutrient status during pregnancy. Apart from having a large sample size, a wide range of micronutrients was examined simultaneously in a community-based study, allowing estimation of the extent of maternal micronutrient deficiencies in early pregnancy in this rural Nepali setting. In addition, we report the extent to which multiple deficiencies coexist, data that are scarce in rural developing country settings. The results of the present study also have the potential to provide valuable reference values for assessing nutritional status. However, the assessment of vitamin and mineral status during pregnancy is complicated because there is a general lack of pregnancy-specific laboratory indices for nutritional evaluation (6), and pregnancy itself may alter "normal" values (9) independently of the effects of hemodilution. Furthermore, because of the lack of standardization of the assay and different cutoff values to define deficient status, the prevalence of a nutrient deficiency may vary between studies.
Inadequacy of a single nutrient is most likely associated with deficiencies of other micronutrients. Our population study provides evidence that rural pregnant women in South Asia are likely to suffer from multiple deficiencies. This was evident from our estimate that simultaneous deficiencies for 2 micronutrients affected 82% of women who entered the trial early in pregnancy. The likelihood of certain micronutrient deficiencies was higher in the presence of specific other micronutrient deficiencies, suggesting potential metabolic interactions. For example, among women with vitamin A deficiency, nearly half or more also had vitamin E, riboflavin, and vitamin B-6 deficiencies and were anemic, substantially above their respective univariate rates in the population. Joint, apparently noninteractive deficiencies were also evident, suggested by comparable index and conditional prevalences. For example, B-complex vitamin (riboflavin, vitamins B-6 and B-12) and iron deficiencies were comparable irrespective of concurrent zinc deficiency, possibly derived in part from a shared dietary deficit of good food sources such as meat, little of which is consumed in this setting (data not shown) and elsewhere in rural South Asia. Compounding the adverse effects of infrequent intake of micronutrient-rich foods is also a diet that is characteristically high in inhibitors of mineral absorption. Phytates, for example, which are abundant in rice and other grains, inhibit zinc absorption in particular (32); this could help explain the higher prevalence of this nutrient deficit.
Coexisting nutritional deficiencies could reduce the potential benefit of a single nutrient supplement in improving nutrition status and morbidity (33,34). The role of vitamin deficiencies in the etiology of anemia was described (33–36). Specifically, vitamin A, riboflavin, vitamin B-6, vitamin B-12, and folate exert hematopoietic function (35–37), suggesting that anemic women should possibly be supplemented not only with iron but also with vitamin A (33) and other micronutrients (36,37). However, less is known about metabolic interactions of micronutrients. Zinc may interact with vitamin A to potentiate the effect of vitamin A in restoring night vision among night-blind pregnant women with low initial serum zinc concentrations (38).
The diet of the majority of rural Nepalese is monotonous and low in vegetables and animal sources (39); it is highly dependent on a largely local market system and seasonal availability. In Nepal, in the period before the monsoon season, the availability of fruit and vegetables drops dramatically, causing an increase in their prices (39). The rainy monsoon season causes pronounced seasonal shortages, whereas vegetables tend to be more abundant in the dry, mid-winter season. Such variation in availability, and cost, of various foods can affect the status of certain micronutrients. In the present study, for example, biochemical concentrations of most, although not all, assessed micronutrients were higher in the dry, mid-winter months. Alternatively, late dry season concentration peaks in serum ß-carotene and vitamin B-6 presumably correspond to the mango harvest and to increased banana availability at that time of year in the southeastern plains of Nepal. Previously, we found maternal night blindness prevalence to increase during the hot summer months before the monsoon season, but then to decline during the short mango season in June–July (40), mimicking the seasonal dynamic in xerophthalmia that has long been reported among South Asian children (41). A seasonal pattern in Hb was similar to that reported by Bondevik et al. (12) in pregnant women in a hospital setting in Nepal, in which the prevalence of anemia was highest during and after the monsoon period. No seasonal variation was observed in serum concentrations of vitamin B-12 and ferritin, similar to reports by Ronnenberg et al. (7) among Chinese women and Backstrand et al. (42) among Mexican women. Vitamin D concentrations peaked in the monsoon and hot summer months, presumably in response to increased exposure to sunlight. Exposure to UV light during the monsoon season may be high, despite cloud cover, because of the planting and other agricultural work in which women may be involved during this season (43). Knowing the high-risk seasonal periods for maternal micronutrient deficiencies can aid in developing and targeting interventions for their control.
In summary, we report here the population prevalence of low and deficient maternal status with respect to multiple micronutrients in the Southern plains of Nepal, based on published serum concentration cutoff values. We found that >80% of women exhibited evidence of 2 micronutrient deficiencies, and that seasonality can markedly and differentially influence maternal status, likely associated with seasonality of micronutrient-rich foods as well as other potential epidemiologic risk factors (e.g., infection). Because the findings reflect maternal status in the 1st trimester of pregnancy, they may be also taken to represent the burden of micronutrient deficiency in rural women of reproductive age in this population, and provide regional guidance on approaches and timing to the control of multiple micronutrient deficiencies early in pregnancy and throughout the reproductive years in rural South Asia.
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ACKNOWLEDGMENTS |
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FOOTNOTES |
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3 Abbreviations used: Hb, hemoglobin; MUAC, mid-upper arm circumference; NIST, the National Institute of Standards and Technology.
Manuscript received 2 November 2004. Initial review completed 26 December 2004. Revision accepted 14 February 2005.
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