The Association Among Maternal Index of Nutritional Quality, Dietary Antioxidant Index, and Odds of Miscarriage Incidence: Case-Control Study

Abstract

Objective

Miscarriage is a pregnancy condition in which the fetus or embryo naturally dies before being able to survive independently. According to studies, diet and dietary factors are associated with the risk of miscarriage (pregnancies <20 weeks). A 168-item semi-quantitative feed frequency questionnaire was used to estimate the Dietary Antioxidant Index (DAI) and the Index of Nutritional Quality (INQ). We aimed to assess the relationship between INQ and DAI with odds of miscarriage.

Method

In summary, 135 Iranian women with a history of three or more miscarriages were included. We calculated the INQ using the following formula: INQ = consumed amount of a nutrient per 1,000 kcal/Recommended Dietary Allowance of that nutrient per 1,000 kcal. We standardized each dietary vitamins/minerals by subtracting the global mean and dividing the result by the universal standard deviation to compute DAI. We computed the DAI by summing up the standardized intakes of these vitamins and minerals and equal weight.

Results

Regression models were used to extract the odds ratios (ORs) and 95% confidence intervals (CIs) in crude and multivariate adjustments. Controls significantly had higher INQ of vitamin B12, niacin, vitamin D, vitamin E, vitamin C, and zinc. Modeling INQs of vitamin D (OR: 0.004, 95% CI, 0.00–0.025) and B12 (OR: 0.04, 95% CI, 0.005–0.41) as a continuous variable showed a significant and protective effect in multivariate adjustment. Modeling DAI as a categorical variable showed a significant protective effect (OR_{DAI<0.054vs.DAI ≥0.054} = 0.43, 95% CI, 0.20–0.91).

Conclusions

Recommending a diet rich in antioxidants such as vitamin E, C, zinc, and selenium and a quality diet containing vitamins B12 and D can be considered an effective strategy to reduce the odds of miscarriage in women with a history of recurrent miscarriage.

Keywords:

• Miscarriage
• abortion
• index of nutritional quality (INQ)
• dietary antioxidant index (DAI)
• diet quality
• antioxidants
• pregnancy

Disclosure statement

The authors declare no conflict of interest.

Authors’ contributions

Design: FV, DR, AH. Conduct/data collection: FV, DR, and SHD, Writing manuscript: FV, AH, and SHD.

All authors drafted the manuscript, critically revised the manuscript, agreed to be fully accountable for ensuring the work's integrity and accuracy, and read and approved the final manuscript.

Acknowledgment

We would like to thank Dr Diyako Rahmani for the technical editing of the article.