Miscarriage is a heartbreaking and emotionally challenging experience that affects many women worldwide, with more than one in five pregnancies ending in miscarriage, according to the Miscarriage Association (2021). With the majority happening within the first 12 weeks, chromosomal abnormalities is one of the main reasons, meaning the foetus with extra, or missing chromosomes (due to abnormalities with the sperm, egg, or both) is unable to develop properly. However, 50% of miscarriages are still unexplained.
Researchers are constantly exploring various factors that may contribute to or reduce the risk of miscarriage, with one area of investigation being the impact of dietary patterns. Diet can play a role in your overall health, including reproductive health, and findings from a recent (2023) study confirm that it may have some impact on the risk of miscarriage. Reproduction demands a great deal of energy and relies on the availability of specific nutrients, and there’s more and more evidence highlighting the importance of preconception health and nutrition with regards to outcomes for mother and baby.
**It's important to note that miscarriages can occur for a variety of reasons, many of which are beyond your control and diet alone is not the sole factor in preventing or causing miscarriages.**
Despite there being no evidence-based guidelines with regards to diet and miscarriage, couples often wish to know whether there are any specific food groups or dietary patterns that have been associated with increased risk.
The particular study sheds light on the relationship between what we eat and the risk of miscarriage. As a systematic review and meta-analysis, it examines a wide range of existing research on the topic and gathers the data together for more in-depth analysis. This provides a clearer picture and also makes the research more valid.
13,183 healthy women of reproductive age were included in the research, a mixture of 2 cohort and 4 case-controlled, and their diet before conception and during the time of their pregnancy was explored. The outcome of the study was the rate of miscarriage.
It was found that high intakes of fruit and vegetables was associated with a reduction in miscarriage rates when compared with low intakes. A significant 61% and 41% reduction, respectively. Fruit and vegetables have a high availability of nutrients including phytochemicals, vitamins, minerals and fibre which have antioxidant and anti-inflammatory effects. It is known that oxidative stress (OS) plays a key role in initiating and the progression of many different diseases, and reproductive health isn’t an exception, with studies suggesting a link between OS and poor fertility outcomes for both men and women; including an increased miscarriage risk. A diet rich in fruit and vegetables that includes a range of different colours is beneficial for overall health, including reproductive health.
Regarding seafood, compared with low intake, a high intake was associated with 19% reduction in miscarriage odds. Seafood contains high-quality protein and essential nutrients such as niacin, vitamin B, vitamin D, selenium, and omega-3 fatty acids which are beneficial for the reproductive health of men and women, however, it is also a recognised source of environmental toxins and contaminants such as mercury, organic pollutants, and polychlorinated biphenyls. The amount of seafood and type is therefore important. It is recommended that 2 portions of fish is consumed a week, with one of these being an oily source such as salmon, mackerel or trout. High mercury fish and raw shellfish should be avoided when trying to conceive and throughout pregnancy.
Higher intake of dairy and eggs was associated with a 37% and 19% reduction in miscarriage rates, respectively. Dairy products and eggs are good sources of protein with high nutrient density and bioavailability. With dairy being rich in calcium, iodine, phosphorus, potassium, and vitamin B12, among others, increasing maternal intake has consistently been associated with promoting foetal and neonatal growth. Eggs on the other hand contain good amounts of omega-3 fatty acids, vitamin A, B, D, selenium and choline which are key nutrients during fertility and pregnancy.
Higher cereal/grain intake may be associated with a 33% reduction in miscarriage rates compared with lower intake. They are an excellent source of carbohydrates providing a good energy source for the increased demands during pregnancy, are cholesterol free, low in saturated fat, and high in fibre and other nutrients. Research also suggests that increasing intake of whole grains increases the endometrial lining thickness which can support successful implantation. It is important to note that the effect of grain consumption may be influenced by multiple factors including grain type or processing techniques, therefore choosing wholegrains over the white, refined varieties is important. Ensure your meals contain a portion of wholegrains such as brown rice or pasta, quinoa, buckwheat, bulgur wheat or whole meal bread.
The findings were unclear or conflicting for meat, red meat, white meat, fat and oil, sugar substitutes, refined sugar and soft drinks, sweets, nuts, soya products, processed meat, and plant-based proteins.
However, whilst this data is useful, there is increasing recognition of the need to move toward evaluating diet as a whole as food is not consumed in isolation. The interaction between different foods may modify their overall nutritional effect, therefore a balanced diet rich in whole foods is associated with a reduction in miscarriage odds, and higher consumption of a pro-inflammatory diet or processed food is found to increase the risk of miscarriage.
Either way, maintaining a healthy diet is good practice, and those planning to conceive or are already pregnant should consider adopting a balanced, nutrient-rich diet and lifestyle habits that promote a healthy pregnancy.