Risks and Rewards of a Vegan Diet During Pregnancy

Risks and Rewards of a Vegan Diet During Pregnancy

The number of people following variations of plant-based diets has risen worldwide in the past decade. Strong data continues to come out around the positive health outcomes of restricting animal products and increasing consumption of fruits, vegetables, grains, nuts and seeds as well as fermented foods. Evidence suggests that following a plant-based diet may decrease the risk of coronary heart disease, cancer and type 2 diabetes. While this may be true, there is some data that associates vegan and vegetarian diets with a higher incidence of vitamin and nutrient deficiencies, specifically of protein, iron, omega-3 and vitamin B12 which are scarcer amongst plant-based foods. To reach and maintain sufficient nutrition, plant-based diets require a proper amount of awareness and planning in order to achieve essential nutrient intake. Not only are these risks important to consider for anyone looking to safely follow a plant-based diet, it is especially important for women during pregnancy to be aware of the risks certain restrictive diets pose.

“Healthy and balanced maternal nutrition is imperative for the mother and child’s health during and after the pregnancy term.”

Healthy and balanced maternal nutrition is imperative for the mother and child’s health during and after the pregnancy term. According to the “early life programming” theory, environmental factors and lifestyle choices during pregnancy play a major role in the fetal development and determined risk of chronic diseases and lifelong health in the offspring. Considering the importance of the mother’s nutrition while child-bearing, there has been concern around the safety of vegan and vegetarian diets during pregnancy. The maternal diet during pregnancy has a direct effect on the newborn’s metabolism, such as impaired bone mass during childhood, while low maternal B12 levels are associated with insulin resistance and changes in lipid profile ratio in the umbilical cord. Mother’s with a low BMI and those who show signs of malnourishment are at risk of causing impaired fetal development and nutrients supply, which can lead to adverse health outcomes including physical and cognitive delays in childhood and metabolic disorders in adulthood.

“There’s little research on the effects of vegan diets on pregnancy outcomes and the data that is currently out there tends to be inconsistent due to the varied social, cultural, and dietary patterns of the studies available.”

There’s little research on the effects of vegan diets on pregnancy outcomes and the data that is currently available tends to be inconsistent due to the varied social, cultural, and dietary patterns of the studies available. A prospective observational study conducted at Tel-Aviv University between May 2018 and June 2019 focused on the association between specific maternal diet and pregnancy outcomes, especially intrauterine growth restriction and preterm birth. This was observed by comparing women who followed vegan diets to women who followed lacto–ovo–vegetarian, pescatarian, and omnivore diets. Lacto-ovo vegetarians (LOV) exclude meat, fish and poultry from their diets but include eggs and dairy products, pescetarians (or fish-eaters) exclude meat and poultry, but typically consume fish, eggs and dairy products and vegans exclude all of the above animal-based food groups and only consume plant-based foods. All participants had to have followed the same diet 3 months prior to and throughout their pregnancy term and could not have a medical indication for a specific restrictive diet such as celiac disease, lactose intolerance, inflammatory bowel disease and could not have undergone bariatric surgeries. Of the 273 women enrolled in this study, 112 were omnivores, 37 were fish-eaters, 64 were LOV, and 60 were vegans. It may be worth noting that the vegan women were older and had lower BMIs pre pregnancy than the other participants. The women were split up into groups based on their diet: vegans who consumed only plant-based products, LOV, who consumed mainly plant-based products but also dairy products and eggs, fish-eaters, who include fish products in their LOV diet, and omnivores, who consume animal-based and plant-based products.

“The leaders of the study make it clear that their findings should not be used to dissuade vegans from following their plant-based diets.”

The primary outcome of the study was preterm birth (prior to 37 weeks) and small for gestational age (SGA: birthweight below the 10% percentile). The study found that the incidence of SGA among vegans was significantly higher than those of the omnivores, but not when compared to the LOV and fish-eaters. No difference was found for the incidence of hypertensive complications, preterm birth or gestational weight gain amongst the four diet groups. The overall findings suggest that a vegan diet is associated with lower gestational weight gain, lower birth weight newborns and SGA (birthweight below the 10% percentile). Although these observations are definitely worth taking into account when deciding which diet is right during pregnancy, the leaders of the study make it clear that their findings should not be used to dissuade vegans from following their plant-based diets and recommend undergoing regular check ups around maternal weight and fetal weight estimation to be sure of a healthy pregnancy.

“Plant-based diet variations can be safe and healthy during pregnancy as long as they are well planned and provide all essential vitamins and nutrients needed.”

Plant-based diets tend to be high in fiber and low in sugar and fat which have been shown to have positive impacts on pregnancy outcomes. The high fiber content of vegan and vegetarian diets may even protect against certain pregnancy complications such as preeclampsia, which is caused by high blood pressure. The overarching message amongst the data available is that plant-based diet variations can be safe and healthy during pregnancy as long as they are well planned and provide all essential vitamins and micronutrients needed, which may include taking supplements. Women interested in maintaining or following vegan or vegetarian diets during pregnancy should consider seeking guidance from a registered dietician to make sure they are getting the proper nutrition to support a healthy pregnancy.


Juliette Frank is a UCLA student majoring in Public Affairs with a minor in Food Studies. Her interests include the interrelation between food systems, digestive health and the environmental impacts of food production.