Locally harvested foods support serum 25-hydroxyvitamin D sufficiency in an indigenous population of Western Alaska

Diet quality is positively associated with intake of traditional foods and does not differ by season in remote Yup'ik communities

This study evaluated whether traditional food intake and diet quality differed by season in Yup'ik communities and examined the relationship between intake of traditional food groups and diet quality. Data were collected from 38 participants, ages 14-79 years, from two Yup'ik communities in Southwest Alaska from 2008 to 2010. Self-reported intake (24-h recalls) and dietary biomarker (nitrogen stable isotope ratio) data were collected twice in distinct seasons. Diet quality was assessed using the Healthy Eating Index. A paired sample t-test was used to test for seasonal differences in traditional food intake and diet quality, and linear regression was used to evaluate associations between traditional food intake and diet quality. Total traditional food intake and overall diet quality did not significantly differ by season, but there were differences in traditional food group intake and diet quality component scores. Diet quality was strongly associated with intake of traditional food groups including fish, tundra greens, and berries. Given the strong relationship between traditional food intake and diet quality, policies should aim to ensure continued access to traditional foods in Yup'ik communities amid environmental changes in the circumpolar North.

Alaska Native Parents' Decision-Making About Food, Beverages, and Screen Time for Young Children: Formative Insights From the "Got Neqpiaq?" Project

With rising childhood obesity rates, ensuring children adopt healthy habits early is imperative. Given the unique context for Alaska Native families living in rural remote communities, who are concurrently experiencing changes in traditional practices, we investigated what impacts parents' decisions as they relate to daily living before revising a preschool curriculum focused on healthy habits. The objective of this study was to explore factors influencing parents' decisions about their children's foods, beverages, and activities. In focus group discussions with AN parents of young children across 12 communities, we asked about meals, traditional foods, beverages, physical activity, and screen time. All sessions were recorded, transcribed, and analyzed using open and selective coding to allow the most important themes to emerge. As parents discussed how they make decisions, several trends emerged related to adults' and children's food and beverage preferences; the impact of adult modeling on children; and how convenience, seasonality, access, and a reluctance to engage in conflict all impact decision-making. Parents and other community members shared important perspectives on exposing children to traditional subsistence foods and activities and passing important traditional knowledge to them at an early age. These perspectives will form the basis for preschool curricula in these communities.

Habitual Intake of Marine-Derived n-3 PUFAs is Inversely Associated with a Cardiometabolic Inflammatory Profile in Yup'ik Alaska Native People

BACKGROUND

The relationship between dietary n-3 PUFAs and the prevention of cardiometabolic diseases, including type 2 diabetes, is unresolved. Examination of the association between n-3 PUFAs and chronic low-grade inflammation in a population where many individuals have had an extremely high intake of marine mammals and fish throughout their lifespan may provide important clues regarding the impact of n-3 PUFAs on health.

OBJECTIVES

The aim of this study was to explore associations between concentrations of n-3 PUFAs resulting from habitual intake of natural food sources high in fish and marine mammals with immune biomarkers of metabolic inflammation and parameters of glucose regulation.

METHODS

A total of 569 Yup'ik Alaska Native adults (18-87 years old) were enrolled in this cross-sectional study between December 2016 and November 2019. The RBC nitrogen isotope ratio (NIR; 15N/14N) was used as a validated measure of n-3 PUFA intake to select 165 participant samples from the first and fourth quartiles of n-3 PUFA intakes. Outcomes included 38 pro- and anti-inflammatory cytokines and 8 measures of glucose homeostasis associated with type 2 diabetes risks. These outcomes were evaluated for their associations with direct measurements of EPA, DHA, and arachidonic acid in RBCs.

ANALYSIS

Linear regression was used to detect significant relationships with cytokines and n-3 PUFAs, adiposity, and glucose-related variables.

RESULTS

The DHA concentration in RBC membranes was inversely associated with IL-6 (β = -0.0066; P < 0.001); EPA was inversely associated with TNFα (β = -0.4925; P < 0.001); and the NIR was inversely associated with Monocyte chemoattractant protein-1 (MCP-1) (β = -0.8345; P < 0.001) and IL-10 (β = -1.2868; P < 0.001).

CONCLUSIONS

Habitual intake of marine mammals and fish rich in n-3 PUFAs in this study population of Yup'ik Alaska Native adults is associated with reduced systemic inflammation, which may contribute to the low prevalence of diseases in which inflammation plays an important role.

Alaska Native Elders' perspectives on dietary patterns in rural, remote communities

BACKGROUND

Given the increasing rates of childhood obesity in Alaska Native children and the understanding that the most effective interventions are informed by and reflect the cultural knowledge of the community in which they are implemented, this project sought to gather the wisdom of local Yup'ik and Cup'ik Elders in the Yukon-Kuskokwim region of Alaska around how to maintain a healthy diet and active lifestyle.

METHODS

Perspectives were sought through the use of semi-structured focus groups, which were completed in person in twelve communities. All conversations were recorded, translated, transcribed, and analyzed using a qualitative approach, where key themes were identified.

RESULTS

Elders provided a clear and consistent recollection of what their life looked like when they were young and expressed their perspectives related to maintaining a healthy and traditional lifestyle. The key themes the Elders discussed included an emphasis on the nutritional and cultural benefits of traditional foods; concerns around changing dietary patterns such as the consumption of processed foods and sugar sweetened beverages; and concerns on the time and use of screens. Elders also expressed a desire to help younger generations learn traditional subsistence practices.

CONCLUSIONS

The risk of obesity in Alaska Native children is high and intervention efforts should be grounded in local knowledge and values. The perspectives from Yup'ik and Cup'ik Elders in the Yukon-Kuskokwim Delta area of Alaska provide a better understanding on local views of how to maintain a healthy diet, physical activities, and traditional values.

Subsistence fish consumption in rural Alaska: Using regional monitoring data to evaluate risk and bioavailability of dietary methylmercury

On average, Alaskans in rural communities consume over three times the Federally recommended maximum weekly fish ingestion rate (IR), the overwhelming majority of which is Pacific salmon. Results of statewide monitoring efforts consistently show that Pacific salmon from Alaska have low concentrations of mercury, yet concerns regarding dietary exposure to methylmercury (MeHg) and other aquatic contaminants continue to contribute to declining subsistence fish consumption rates in rural communities. Therefore, the goal of the present study was to use statewide biomonitoring datasets and regional fish IRs to quantitatively evaluate potential risk from dietary MeHg exposure via subsistence consumption of salmon from Alaska. Hazard Indices (HIs) did not exceed 1 for any of the groups evaluated, indicating negligible risk for the average Alaskan subsistence consumer. Selenium health benefit values (HBV_Se) of various fish species from AK were also calculated, with positive results for all commonly consumed subsistence species. Additionally, mercury concentrations in the hair of Alaskan women were evaluated as a proxy for dietary MeHg exposure. Results reveal that Alaskan women of childbearing age have substantially lower hair Hg concentrations than their counterparts in other large-scale biomonitoring studies, despite similar fish IRs. Collectively, results of the present study suggest that MeHg in Pacific salmon does not pose an unacceptable hazard for the average subsistence consumer in Alaska.

The Nitrogen Isotope Ratio Is a Biomarker of Yup'ik Traditional Food Intake and Reflects Dietary Seasonality in Segmental Hair Analyses

BACKGROUND

The nitrogen isotope ratio (NIR) is a promising index of traditional food intake for an Alaska Native (Yup'ik) population, which can be measured in blood and hair. However, the NIR has not been calibrated to high-quality measures of Yup'ik traditional food intake.

OBJECTIVES

Our primary objective was to examine associations between intakes of Yup'ik traditional food groups, including fish, marine mammals, birds, land mammals, berries, greens, and total traditional foods, and the NIR. In an exploratory analysis, we also examined whether NIR analyzed sequentially along hair could reflect dietary seasonality.

METHODS

We recruited 68 participants from 2 Yup'ik communities in the Yukon Kuskokwim region of Southwest Alaska (49% female, aged 14-79 y). Participants completed 4 unscheduled 24-h food recalls over the period peak of RBC and hair synthesis preceding a specimen collection visit. The NIR was measured in RBCs ( n = 68), a proximal hair section (n = 58), and sequential segments of hair from individuals in the upper 2 quartiles of traditional food intake having hair >6 cm in length, plus 2 low subsistence participants for reference (n = 18). Diet-biomarker associations were assessed using Pearson's correlation and linear regression.

RESULTS

Intakes of fish, marine mammals, berries, and greens were significantly associated with the NIR. The strongest dietary association was with total traditional food intake (R2 = 0.62), which indicated that each 1‰ increase in the RBC NIR corresponded to 8% of energy from traditional foods. Hair NIR appeared to fluctuate seasonally in some individuals, peaking in the summertime.

CONCLUSIONS

Findings support the use of the RBC and hair NIR to assess total traditional food intake in a Yup'ik population. Analyses of sequential hair NIR provided evidence of seasonality in traditional food intake, although seasonal variations were modest relative to interindividual variation.

Strengthening adolescents' connection to their traditional food system improves diet quality in remote Alaska Native communities: results from the Neqa Elicarvigmun Pilot Study

In remote Alaska Native communities, traditional foods are inextricably linked to health and food security. Degradation of the traditional food system over the past several decades has resulted in a shift in dietary patterns that have contributed to increased rates of chronic diseases and food insecurity among Alaska Native People. Interventions are needed to address this. Our objectives were to evaluate the preliminary efficacy of a school-based intervention-Neqa Elicarvigmun or the Fish-to-School Program-on diet quality, fish intake, and attitudes and beliefs around traditional foods (specifically fish) using a pre-post comparison group design with data collection occurring at three time points. Study participants were 76 middle and high school students in two remote Alaska Native communities (population <900) in southwestern Alaska. We used a participatory approach to design the school-based, multilevel intervention that included activities in the cafeteria, classroom, and community. Multilevel analyses showed that students in the experimental community showed significant improvements in diet quality compared to the comparison community (Beta = 4.57; p < .05). Fish intake, measured using the stable nitrogen isotope ratio of hair, a validated biomarker, also increased significantly in the experimental community (Beta = 0.16; p < .05). Leveraging the cultural and physical resources of the traditional food system for the Neqa Elicarvigmun program represents a strength-based approach that improves diet quality, increases adolescents' connection to their traditional culture, and by promoting the local food system supports food security. Embedding the program into the local culture may result in faster adoption and greater sustainability of the program.

Association of Maternal Vitamin D Deficiency with Early Childhood Caries

Alaska Native (AN) children experience one of the highest reported rates of severe early childhood caries (S-ECC). Serum vitamin D concentrations in AN childbearing women in the Yukon Kuskokwim Delta (YKD) region have decreased since the 1960s to currently low levels, related to a decrease in traditional marine diet. Recent studies suggest an association between prenatal vitamin D (25(OH)D) concentrations in mothers and S-ECC in their infants. We used independent t tests to analyze the influence of prenatal 25(OH)D levels in YKD AN mothers on S-ECC in their children using data collected in the Maternal Organics Monitoring Study (MOMS). Maternal 25(OH)D levels were assessed at prenatal visits and in cord blood. We queried electronic dental records to assess early childhood caries (ECC) status using highest decayed, missing, filled, primary teeth (dmft) scores at 12 to 59 mo of age. We examined prenatal and cord blood for 76 and 57 mother/infant pairs, respectively. Children 12 to 35 mo of age with "deficient" cord blood (25(OH)D <30 nmol/L) had a mean dmft score twice as high as children who were "nondeficient" at birth (9.3 vs. 4.7; P = 0.002). There was no significant difference in mean dmft scores for children aged 36 to 59 mo with deficient versus nondeficient cord blood 25(OH)D (10.9 vs. 8.7 P = 0.14). There was no significant difference in mean dmft scores for children aged 12 to 35 mo whose mothers had "sufficient" versus "insufficient" 25(OH)D during prenatal visits (9.0 vs. 7.4; P = 0.48). In this small sample, children with deficient vitamin D levels in cord blood had a dmft score at 12 to 35 mo 2-fold higher than children with nondeficient cord blood. Maternal 25(OH)D may influence the primary dentition, and improving vitamin D status in pregnant women might affect ECC rates in their infants.

A scoping review of traditional food security in Alaska

BACKGROUND

Food insecurity is a public health concern. The pillars of food security include food access, availability and utilisation. For some indigenous peoples, the pillars may focus on traditional foods.

OBJECTIVE

To conduct a scoping review on traditional foods and food security in Alaska.

DESIGN

Google Scholar and the High North Research Documents were used to search for relevant primary research using the following terms: “traditional foods”, “food security”, “access”, “availability”, “utilisation”, “Alaska”, “Alaska Native” and “indigenous”.

RESULTS

Twenty four articles from Google Scholar and four articles from the High North Research Documents met the inclusion criteria. The articles revealed three types of research approaches, those that quantified traditional food intake (n=18), those that quantified food security (n=2), and qualitative articles that addressed at least one pillar of food security (n=8).

CONCLUSIONS

Studies that estimate the prevalence of traditional food insecurity in Alaska are virtually absent from the literature. Instead most studies provide a review of factors related to food security. Research investigating dietary intake of traditional foods is more prevalent. Future research should include direct measurements of traditional food intake and food security to provide a more complete picture of traditional food security in Alaska.

Declines in traditional marine food intake and vitamin D levels from the 1960s to present in young Alaska Native women

OBJECTIVE

To measure the trends in traditional marine food intake and serum vitamin D levels in Alaska Native women of childbearing age (20-29 years old) from the 1960s to the present.

DESIGN

We measured a biomarker of traditional food intake, the δ15N value, and vitamin D level, as 25-hydroxycholecalciferol (25(OH)D3) concentration, in 100 serum samples from 20-29-year-old women archived in the Alaska Area Specimen Bank, selecting twenty-five per decade from the 1960s to the 1990s. We compared these with measurements of red-blood-cell δ15N values and serum 25(OH)D3 concentrations from 20-29-year-old women from the same region collected during the 2000s and 2010s in a Center for Alaska Native Health Research study.

SETTING

The Yukon Kuskokwim Delta region of south-west Alaska.

SUBJECTS

Alaska Native women (n 319) aged 20-29 years at the time of specimen collection.

RESULTS

Intake of traditional marine foods, as measured by serum δ15N values, decreased significantly each decade from the 1960s through the 1990s, then remained constant from the 1990s through the present (F 5,306=77·4, P<0·0001). Serum vitamin D concentrations also decreased from the 1960s to the present (F 4,162=26·1, P<0·0001).

CONCLUSIONS

Consumption of traditional marine foods by young Alaska Native women dropped significantly between the 1960s and the 1990s and was associated with a significant decline in serum vitamin D concentrations. Studies are needed to evaluate the promotion of traditional marine foods and routine vitamin D supplementation during pregnancy for this population.

Linkage and association analysis of circulating vitamin D and parathyroid hormone identifies novel loci in Alaska Native Yup'ik people

BACKGROUND

Vitamin D deficiency is a well-documented public health issue with both genetic and environmental determinants. Populations living at far northern latitudes are vulnerable to vitamin D deficiency and its health sequelae, although consumption of traditional native dietary pattern rich in fish and marine mammals may buffer the effects of reduced sunlight exposure. To date, few studies have investigated the genetics of vitamin D metabolism in circumpolar populations or considered genediet interactions with fish and n-3 fatty acid intake.

METHODS

We searched for genomic regions exhibiting linkage and association with circulating levels of vitamin D and parathyroid hormone (PTH) in 982 Yup'ik individuals from the Center for Alaska Native Health Research Study. We also investigated potential interactions between genetic variants and a biomarker of traditional dietary intake, the δ15N value.

RESULTS

We identified several novel regions linked with circulating vitamin D and PTH as well as replicated a previous linkage finding on 2p16.2 for vitamin D. Bioinformatic analysis revealed multiple candidate genes for both PTH and vitamin D, including CUBN, MGAT3, and NFKBIA. Targeted association analysis identified NEBL as a candidate gene for vitamin D and FNDC3B for PTH. We observed significant associations between a variant in MXD1 and vitamin D only when an interaction with the δ15N value was included. Finally, we integrated pathway level information to illustrate the biological validity of the proposed candidate genes.

CONCLUSION

We provide evidence of linkage between several biologically plausible genomic regions and vitamin D metabolism in a circumpolar population. Additionally, these findings suggest that a traditional dietary pattern may modulate genetic effects on circulating vitamin D.

Impacts of decline harvest of country food on nutrient intake among Inuit in Arctic Canada: impact of climate change and possible adaptation plan

Background

The pervasive food insecurity and the diet transition away from local, nutrient-rich country foods present a public health challenge among Inuit living in the Canadian Arctic. While environmental factors such as climate change decreased the accessibility and availability of many country food species, new species were introduced into regions where they were previously unavailable. An adaptation such as turning to alternate country food species can be a viable solution to substitute for the nutrients provided by the declined food species. The objective of this study was to estimate the impact on nutrient intake using hypothetical scenarios that current commonly harvested country foods were reduced by 50%, and were replaced with alternate or new species.

Methods

Data collected during the 2007–2008 Inuit Health Survey from 36 Canadian Arctic communities spanning Nunavut, the Inuvialuit Settlement Region and Nunatsiavut were used.

Results

A 50% decline in consumption of fish, whale, ringed seals and birds (the food that was reported to be in decline) resulted in a significant decrease in essential nutrient intake. Possible substitute foods were identified but some nutrients such as zinc and especially vitamin D were most often found lacking in the alternative diet.

Conclusions

If the alternative species are not available or feasible, more expensive and less nutritionally dense store-bought foods may be sought. Given the superior quality of country foods and their association with food security, and Inuit cultural health and personal identity, developing skills and awareness for adaptation, promoting regional sharing networks, forming a co-management agency and continuing nutritional monitoring may potentially preserve the nutritional integrity of Inuit diet, and in turn their health and cultural survival.

Genetics, Diet, and Season Are Associated with Serum 25-Hydroxycholecalciferol Concentration in a Yup'ik Study Population from Southwestern Alaska

BACKGROUND

Low blood vitamin D concentration is a concern for people living in circumpolar regions, where sunlight is insufficient for vitamin D synthesis in winter months and the consumption of traditional dietary sources of vitamin D is decreasing.

OBJECTIVE

The objective was to characterize the effects of diet, genetic variation, and season on serum 25-hydroxycholecalciferol [25(OH)D3] concentrations in Yup'ik Alaska Native people living in rural southwest Alaska.

METHODS

This study was a cross-sectional design that assessed the associations of traditional diet (via a biomarker, the RBC δ(15)N value), age, gender, body mass index (BMI), community location, and genotype of select single nucleotide polymorphisms (SNPs) in cytochrome P450 family 2, subfamily R, peptide 1 (CYP2R1), 7-dehydrocholesterol reductase (DHCR7), and vitamin D binding protein (GC) with serum 25(OH)D3 concentrations in 743 Yup'ik male and female participants, aged 14-93 y, recruited between September 2009 and December 2013.

RESULTS

Yup'ik participants, on average, had adequate concentrations of serum 25(OH)D3 (31.1 ± 1.0 ng/mL). Variations in diet, BMI, age, gender, season of sample collection, and inland or coastal community geography were all significantly associated with serum 25(OH)D3 concentration. In models not adjusting for other covariates, age, diet, and seasonal effects explained 33.7%, 20.7%, and 9.8%, respectively, of variability in serum 25(OH)D3 concentrations. Of the 8 SNPs interrogated in CYP2R1 and DHCR7, only rs11023374 in CYP2R1 was significantly associated with serum 25(OH)D3, explaining 1.5% of variability. The GC haplotype explained an additional 2.8% of variability. Together, age, diet, gender, season of sample collection, BMI, geography of the community, and genotype at rs11023374 explained 52.5% of the variability in serum 25(OH)D3 concentrations.

CONCLUSIONS

Lower consumption of the traditional diet was associated with lower serum concentrations of 25(OH)D3. Younger adults and youth in this community may be at increased risk of adverse outcomes associated with vitamin D insufficiency compared with older members of the community, especially during seasons of low sunlight exposure, because of lower consumption of dietary sources of vitamin D.

Changes of 25-OH-Vitamin D during Overwintering at the German Antarctic Stations Neumayer II and III

Purpose

Humans in Antarctica face different environmental challenges, such as low ultra-violet radiation, which is crucial for vitamin D production in humans. Therefore we assessed changes in 25-OH-vitamin D serum concentration during 13 months of overwintering at the German Stations Neumayer II and III (2007–2012). We hypothesized that (i) 25-OH-vitamin D serum concentration would significantly decrease, (ii) changes would be affected by age, gender, baseline (i.e. pre-overwintering) fat mass, baseline 25-OH-vitamin D serum concentration, and station residence, and (iii) our results would not differ from similar previous studies in comparable high latitudes.

Materials & Methods

25-OH-vitamin D serum concentrations were determined before, after, and monthly during the campaigns from venous blood samples of n = 43 participants (28 men, 15 women). Baseline fat mass was determined via bio impedance analysis and body plethysmography. Data were analyzed for change over time, dependency on independent parameters, and after categorization for sufficiency (>50nmol/l), insufficiency (25-50nmol/l), and deficiency (<25nmol/l). Results were compared with data from similar previous studies.

Results

We found a significant decrease of 25-OH-vitamin D with dependency on month. Age, gender, fat mass, and station residence had no influence. Only baseline 25-OH-vitamin D serum concentrations significantly affected subsequent 25-OH-vitamin D values.

Conclusions

Overwinterings at the Antarctic German research stations Neumayer II and III are associated with a decrease in 25-OH-vitamin D serum concentrations, unaffected by age, gender, baseline fat mass, and station residence. Higher baseline vitamin D serum concentrations might protect from subsequent deficiencies. Residence at the Neumayer Stations may lead to lower vitamin D serum concentrations than found in other comparable high latitudes.

Linkage and association analysis of obesity traits reveals novel loci and interactions with dietary n-3 fatty acids in an Alaska Native (Yup'ik) population

OBJECTIVE

To identify novel genetic markers of obesity-related traits and to identify gene-diet interactions with n-3 polyunsaturated fatty acid (n-3 PUFA) intake in Yup'ik people.

MATERIAL AND METHODS

We measured body composition, plasma adipokines and ghrelin in 982 participants enrolled in the Center for Alaska Native Health Research (CANHR) Study. We conducted a genome-wide SNP linkage scan and targeted association analysis, fitting additional models to investigate putative gene-diet interactions. Finally, we performed bioinformatic analysis to uncover likely candidate genes within the identified linkage peaks.

RESULTS

We observed evidence of linkage for all obesity-related traits, replicating previous results and identifying novel regions of interest for adiponectin (10q26.13-2) and thigh circumference (8q21.11-13). Bioinformatic analysis revealed DOCK1, PTPRE (10q26.13-2) and FABP4 (8q21.11-13) as putative candidate genes in the newly identified regions. Targeted SNP analysis under the linkage peaks identified associations between three SNPs and obesity-related traits: rs1007750 on chromosome 8 and thigh circumference (P=0.0005), rs878953 on chromosome 5 and thigh skinfold (P=0.0004), and rs1596854 on chromosome 11 for waist circumference (P=0.0003). Finally, we showed that n-3 PUFA modified the association between obesity related traits and two additional variants (rs2048417 on chromosome 3 for adiponectin, P for interaction=0.0006 and rs730414 on chromosome 11 for percentage body fat, P for interaction=0.0004).

CONCLUSIONS

This study presents evidence of novel genomic regions and gene-diet interactions that may contribute to the pathophysiology of obesity-related traits among Yup'ik people.

Vitamin D status and related factors in newborns in Shanghai, China

With the increasing recognition of the importance of the non-skeletal effects of vitamin D (VitD), more and more attention has been drawn to VitD status in early life. However, the VitD status of newborns and factors that influence VitD levels in Shanghai, China, remain unclear. A total of 1030 pregnant women were selected from two hospitals in Shanghai, one of the largest cities in China located at 31 degrees north latitude. Umbilical cord serum concentrations of 25-hydroxy vitamin D [25(OH)D] were measured by LC-MS-MS, and questionnaires were used to collect information. The median cord serum 25(OH)D concentration was 22.4 ng/mL; the concentration lower than 20 ng/mL accounted for 36.3% of the participants, and the concentration lower than 30 ng/mL for 84.1%. A multivariable logistic regression model showed that the determinants of low 25(OH)D status were being born during autumn or winter months and a lack of VitD-related multivitamin supplementation. The relative risk was 1.7 for both autumn (95% CI, 1.1-2.6) and winter (95% CI, 1.1-2.5) births (p < 0.05). VitD-related multivitamin supplementation more than once a day during pregnancy reduced the risk of VitD deficiency [adjusted OR (aOR) = 0.6, 95% CI (0.45-1.0) for VitD supplementation] (p < 0.05). VitD deficiency and insufficiency are common in newborns in Shanghai, China, and are independently associated with season and VitD supplementation. Our findings may assist future efforts to correct low levels of 25(OH)D in Shanghai mothers and their newborn children.