Vegan women run a higher risk of developing life-threatening preeclampsia and having underweight babies, a new study has found.
The University of Copenhagen research, published last week in the journal Acta Obstetricia et Gynecologica Scandinavica, found that babies born to vegan mothers were half a pound lighter on average.
Researchers analyzed the data from 66,738 Danish pregnancies between 1996 and 2002. Of those, 65,872 women identified as omnivores, while 666 said they were fish/poultry vegetarians, 183 were vegetarians, and 18 were vegans.
Based on a questionnaire completed mid-pregnancy, investigators found that protein intake was lower among vegetarians (13.3%) and vegans (10.4%) compared with omnivorous participants (15.4%), SWNS reports.
They observed that low protein intake might be tied to low baby birth weight.
“Intake of micronutrients was also considerably lower among vegans, but when dietary supplements were taken into consideration, no major differences were observed,” the researchers wrote.
They found that mothers who ate fish and poultry had babies that were 0.03 pounds lighter than omnivores, on average.
Vegetarian mothers had the largest babies — 0.07 pounds heavier on average than omnivores.
Among vegan women, pregnancies lasted 5.2 days longer.
The scientists undertook this study because “the number of people adhering to plant-based diets has been increasing dramatically in recent years.”
They said in Denmark, veganism in the general population has gone from being “barely measurable” in 2010 to around 3% in 2022.
In the US, it’s estimated that roughly 5% of the population is vegetarian and about 4% follows a vegan diet.
Physicians recommend women who are pregnant consume around 70 grams of protein per day.
They also advise vegan and vegetarian pregnant women to get enough iron and vitamin B12, found in meat and fish, and vitamin D, calcium, and iodine.
Preeclampsia and related pregnancy disorders affect 5% to 8% of US births, according to the Preeclampsia Foundation.
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The condition, which tends to develop after the 20th week of pregnancy, is characterized by high blood pressure and high levels of protein in the urine.
It can impair kidney and liver function, affect blood clotting, lead to fluid in the lungs, cause seizures, and in severe cases, maternal and infant death.
University of Copenhagen study authors noted that a recent study from Israel and one from the US also found lower birth weights among vegans.
They hope that future research puts more emphasis on exploring the plant-based diets consumed by pregnant women.
“The main limitation of our study … is that the number of vegan pregnancies was extremely low (0.03%; 18 women) relative to the total sample size,” they wrote. “Also, being vegan when recruited into the cohort in 1996–2002 may reflect different habits compared with those following vegan diets today.”