Vegan Diet Linked to Pregnancy Complications

Scientists suggest that adhering to a vegan diet while pregnant may increase the risk of preeclampsia and having a baby with a lower birth weight.

In a study recently published in Acta Obstetricia et Gynecologica Scandinavica, researchers looked at whether following specific plant-based diets impacted pregnancy or birth outcomes.

To conduct the research, the scientists assessed self-reported dietary intake and pregnancy data from 66,738 pregnant women involved in the Danish National Birth Cohort between 1996 and 2002.

Using the results of dietary intake assessments, the team divided the participants into one of four dietary groups — vegetarians who eat fish and poultry, vegetarians who consume dairy and eggs (lacto/ovo), vegans, or omnivores.

Then, they looked at whether the participants experienced any pregnancy complications, such as preeclampsia, and evaluated the newborns' birth weights.

Among the participants, 65,872 followed an omnivorous diet — including plant- and animal-based foods — during pregnancy. Moreover, 666 people identified as fish/poultry vegetarians, 183 said they were lacto/ovo-vegetarians, and 18 followed a vegan diet.

The research team found that pregnant women who adhered to a vegan diet had a higher risk of preeclampsia and an increased chance of having a baby with a lower birth weight than those following an omnivorous diet.

When the scientists assessed the participants' protein consumption, they discovered that intakes were lower among lacto/ovo-vegetarians (13.3%) and vegans (10.4%) than among omnivorous participants (15.4%). In addition, micronutrient intake was also significantly lower among those following a vegan diet. However, dietary supplements resolved this deficiency.

The study's authors suggest that the preeclampsia and lower birth rate risks associated with the vegan diet may be attributable to lower protein intakes. Vegan diets can lack quality protein and specific nutrients such as vitamin B12.

Still, because of the low number of vegan individuals in the study and other factors, people should use caution when interpreting the results.

"The 66,738 pregnancies in this population-based study were recruited over 20 years ago, when few women followed a plant-based or vegan diet. As acknowledged by the authors, their main findings of higher risks of low birth weight and preeclampsia among vegans are subject to some uncertainty, being based on only 18 vegans," said Keith Godfrey, a Professor of Epidemiology and Human Development at the University of Southampton, United Kingdom, in a Science Media Centre release.

Godfrey was not involved in the research.

However, the study's authors point out that the links between following a vegan diet during pregnancy and lower birth weight are consistent with more recent studies. Still, they acknowledge the limitations and suggest more research is needed to clarify whether vegan and other plant-based diets during pregnancy negatively impact maternal and newborn health.