Association of Maternal Serum Vitamin D Level with Risk of Pregnancy-Related Complications and Neonatal Anthropometric Measures: A Prospective Observational Study

Effect of maternal vitamin D status on risk of adverse birth outcomes: a systematic review and dose-response meta-analysis of observational studies

PURPOSE

Accumulating evidence suggests that vitamin D deficiency increases the risk of adverse perinatal outcomes. However, the dose-response relationship between maternal vitamin D status and adverse birth outcomes remains unclear. Focusing on prospective observational studies, we aimed to explore the dose-response relationship of vitamin D status with the risk of low birth weight (LBW), macrosomia (MA), preterm birth (PTB), small for gestational age (SGA), and intrauterine growth restriction (IUGR).

METHODS

Databases including PubMed, Embase, Scopus, and Web of Science were used up to 19 January 2021 to search for observational studies that fulfilled criteria as follows: cohort studies, case-cohort studies, or nested case-control studies. Random-effects models were used to pool relative risks (RRs) and 95% confidence intervals (CIs) in the observational studies.

RESULTS

A total of 72 publications were included in this systematic review and 71 in the meta-analysis. Maternal 25-hydroxyvitamin D (25(OH)D) concentrations were inversely associated with the risk of LBW (RR: 0.65; 95% CI 0.48-0.86), PTB (RR: 0.67; 95% CI 0.57-0.79), and SGA (RR: 0.61; 95% CI 0.49-0.76) in the highest versus lowest meta-analysis, but not associated with MA and IUGR. Linear dose-response analysis showed that each 25 nmol/L increase in 25(OH)D was associated with a 6% and 10% reduction in the risk of PTB (RR: 0.94; 95% CI 0.90-0.98) and SGA (RR: 0.90; 95% CI 0.84-0.97), respectively.

CONCLUSION

Our study suggests that a sufficient vitamin D status during pregnancy is protective against the risk of LBW, PTB, and SGA.

Association between maternal vitamin D levels and risk of adverse pregnancy outcomes: a systematic review and dose-response meta-analysis

Epidemiological studies have investigated the associations between vitamin D and the risk of adverse pregnancy outcomes; however, the results are conflicting and dose-response relationships remain to be confirmed. This study aimed to summarize previous studies on the associations of vitamin D levels with the risk of gestational diabetes mellitus (GDM), pre-eclampsia (PE), gestational hypertension (GH), and caesarean section (C-section), and to clarify the dose-response trends. PubMed, Embase, Scopus, and Web of Science were searched to identify eligible articles. A total of 69 prospective observational studies including cohort studies, case-cohort studies, or nested case-control studies were included in the current systematic review, of which 68 studies were available for meta-analysis. Compared with the lowest level, the highest level of 25(OH)D was significantly associated with a lower risk of GDM (RR: 0.76; 95% CI: 0.66-0.87), PE (RR: 0.74; 95% CI: 0.60-0.90;), and GH (RR: 0.87; 95% CI: 0.79-0.97); however, no significant relationship was found for C-section (RR: 1.00; 95% CI: 0.90-1.12). There was significant between-study heterogeneity for GDM (I² = 69.2%; P_{heterogeneity} < 0.001), PE (I² = 52.0%; P_{heterogeneity} = 0.001), and C-section (I² = 59.1%; P_{heterogeneity} < 0.001), while no heterogeneity was found for GH (I² = 0.0%; P_{heterogeneity} = 0.676). For each 25 nmol L^-1 increase in 25(OH)D, the pooled RR was 0.92 (95% CI: 0.86-0.97) for GDM and 0.89 (95% CI: 0.84-0.94) for PE, respectively. Notably, the dose-response analysis showed a non-linear relationship between maternal 25(OH)D levels and the risk of PE (P_{non-linearity} = 0.009). Our meta-analysis provides further scientific evidence of the inverse association between 25(OH)D levels and the risk of GDM, PE, and GH, which may be useful for the prevention of pregnancy complications. However, more evidence from prospective studies is needed regarding the dietary intake of vitamin D during pregnancy.

The Association Between Dietary Zinc Intake and Health Status, Including Mental Health and Sleep Quality, Among Iranian Female Students

Epidemiological studies have suggested that there is an association between diet and mental health. The aim of the current study was to explore the association between dietary zinc intake and risk of depression, anxiety, and sleep quality distortion among female students of the Semnan University of Medical Sciences in a cross-sectional study. From January through October 2019, 142 female students were randomly selected from the Department of Nutrition and Food Science at the Semnan University of Medical Sciences by simple random sampling. Food frequency questionnaires (FFQs) were used to assess participants' dietary intake over the past 12 months. Depression, anxiety, and sleep quality were examined by the Beck Depression Inventory-II (BDI-II), Beck Anxiety Inventory (BAI), and Pittsburgh Sleep Quality Index (PSQI), respectively. In the analysis, the crude model was adjusted for total energy intake (kcal), while the model was adjusted for energy intake (kcal), age, economic status, physical activity level, serum vitamin D level, and body mass index. Dietary zinc intake is significantly associated with depression (odds ratio (OR) (95% confidence interval (CI)): 2.34 (0.38-4.30)) and anxiety (OR (95% CI): 3.43 (2.36-4.50)), sleep disorders (OR (95% CI): 3.65 (2.16-5.13)), sleep duration (OR (95% CI): 2.62 (0.39-4.86)), and daytime dysfunction (OR (95% CI): 5.31 (2.84-7.78)) in the model, as well as sleep delay (OR (95% CI): 1.80 (1.05-2.55)) and mental quality of sleep (OR (95% CI): 1.63 (1.10-2.15)) in the crude analysis. This cross-sectional study supports the inverse association between dietary zinc intake and mood disorders, including depression and anxiety, and some indices of sleep disturbance in the Iranian female students. Further cohort or intervention studies are required to draw a firm link between dietary zinc intake and mental health.