By: Laila Khatib
Editor’s Note: Some studies serve as a wake-up call for the research community and medical professionals in practice. The study by Chung et al summarized below is one such compelling study. While on the FACTS online elective that teaches medical students and residents about fertility, miscarriage, and more, Laila Khatib chose to review and summarize this study published in 2023. Titled, “The Association between Dietary Patterns and Risk of Miscarriage: A Systematic Review and Meta-analysis,” the review highlights the need for more research to equip medical professionals as they provide pre-conception counseling, particularly for women at higher risk for miscarriage.
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Introduction
Miscarriage is a common cause of pregnancy loss that affects about one in six pregnancies. Around 50% of early pregnancy losses do not have an explanation; thus, physicians lack clarity on how to counsel these patients. It is thought that lifestyle choices may be associated with the health and outcome of a pregnancy. It is also known that over and undernutrition are not conducive to a healthy pregnancy, but the specifics of how nutritional status relates to pregnancy outcomes and miscarriage have not been definitively studied. Additionally, physicians do not have clear guidelines on how to counsel patients regarding nutrition and minimizing the risk of miscarriage.
“Over and undernutrition are not conducive to a healthy pregnancy, but the specifics of how nutritional status relates to pregnancy outcomes and miscarriage have not been definitively studied.”
Methodology
The authors conducted a systematic review and meta-analysis to study the existing data on pre-conception diet and miscarriage risk in healthy, reproductive-aged females. The study sample included more than 63,000 women from various countries spanning five continents. Search criteria were used to identify exposure for the keywords of “diet,” “nutrition,” or “food,” and then to identify outcomes using the keywords “miscarriage,” “abortion,” “pregnancy loss,” or “embryo loss.” The population studied was healthy women of reproductive age who had at least one pregnancy outcome. Observational and interventional studies were included. The intervention or exposure of interest was diet, and the primary outcomes of interest were miscarriage or recurrent miscarriage.
Results
This systematic review and meta-analysis of 20 observational studies investigated the relationship between periconceptual dietary intake and miscarriage risk in healthy women of reproductive age. The results showed that higher intake of certain foods was associated with lower miscarriage rates; these foods included fruits, vegetables, seafood, dairy products, eggs, and cereals. The association was unclear for red meat, white meat, sugar substitutes, fat and oil. Some evidence suggested fast food consumption and a preference for fried foods or lower chocolate intake may be linked to a higher likelihood of miscarriage.
“This systematic review and meta-analysis of 20 observational studies … (found) that higher intake of certain foods was associated with lower miscarriage rates; these foods included fruits, vegetables, seafood, dairy products, eggs, and cereals.”
Discussion
This study had several strengths. It used a comprehensive search and selection process that was not limited by language or publication status, which reduced inclusion bias and increased generalizability of the findings. The study included data from a wide range of countries across five continents and had a large sample size of over 63,000 women, which enhanced the precision of the results. It also represented more than 22 years of published data.
In terms of limitations, most of the studies focused on women who conceived naturally and had no history of infertility or subfertility, which may introduce selection bias. Despite the extensive literature search, the quality and quantity of the evidence on diet and miscarriage were low and no experimental studies addressed the research question. Observational studies have a high risk of bias, and self-reported dietary information can be influenced by recall and social desirability bias. Ideally, an objective way to assess nutritional exposure would be preferable for more accurate conclusions to be made.
Application in Clinical Practice
As a student in the FACTS elective, I found this topic both interesting and relevant when studying fertility awareness-based methods (FABMs). When patients who desire pregnancy dedicate time and effort to tracking their cycles, they likely have the level of interest and investment to address multiple factors that could influence the health of their pregnancy. Nutrition is one example of a key factor that remains under-studied, though its implications for the health of a pregnancy and reducing miscarriage could be critically important.
“Nutrition is one example of a key factor that remains under-studied, though its implications for the health of a pregnancy and reducing miscarriage could be critically important.”
This review by Chung et al highlights the need for interventional studies on this topic even as we continue to educate our patients on the importance of healthy nutrition as part of pre-conception counseling. There is ample room for future research in this area. Until more data are available, we can encourage our patients to avoid fried and fast foods and incorporate a healthy diet rich in fruits and vegetables, grains, seafood, dairy, and eggs, which may lower the risk of miscarriage.
References
[1] Chung Y, Melo P, Pickering O, Dhillon-Smith R, Coomarasamy A, Devall A. The association between dietary patterns and risk of miscarriage: a systematic review and meta-analysis. Fertil Steril. 2023 Aug;120(2):333-357. doi: 10.1016/j.fertnstert.2023.04.011. Epub 2023 Apr 13. PMID: 37061157
ABOUT THE AUTHOR
Laila Khatib
Laila Khatib is a fourth-year medical student at University of New England College of Osteopathic Medicine. She completed her undergraduate and graduate education at Boston University. She plans to pursue residency in pediatrics and is interested in oncology and public health. She enrolled in the FACTS elective to gain a better understanding of natural family planning methods for personal and general knowledge.
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