Pregnant women who follow a vegan diet face a higher risk of life-threatening pre-eclampsia, and are more likely to birth underweight babies, a new study has found.
Early warning signs of pre-eclampsia include high blood pressure and protein in urine, both of which should be picked up in antenatal appointments.
The study looked at 66,739 pregnant women, of which just 183 identified as vegetarians, and 18 as vegans.
Micronutrient intake, which refers to intake of essential vitamins and minerals, was also found to be lower among vegans, compared to vegetarians or omnivores.
The study, published in the journal Acta Obstetricia et Gynecologica Scandinavica, found that, on average, a baby’s birth weight from a vegan mother was 240g lower than that of a non-vegan mother.
"Those who reported adherence to vegan diets had offspring with a significantly lower mean birth weight, a higher prevalence of being small for gestational age compared with omnivorous women," lead author of the study, Signe Hedegaard, said.
"The prevalence of pre-eclampsia was also higher. Low protein intake might be one plausible explanation for the observed association with birth weight. Further research is needed regarding possible causality between plant-based diets and pregnancy and birth outcomes, to strengthen the basis for dietary recommendations."
While the study did not provide a mechanism for the link between pre-eclampsia and veganism, maternal diet is extremely important to both the mother’s and unborn child’s health.
How diet during pregnancy impacts the mother and baby
"Being a mum comes with a huge amount of worry and guilt, and my main concern is always to reassure pregnant mums, especially those who are struggling to eat, or keep food down, that they have to try and not worry, and the baby will most likely not be harmed," Laura Southern, nutritionist a London Gynaecology explains.
"That said, we do know that maternal diet can affect the unborn baby's health. Firstly a lack of nutrients can be damaging, specifically folic acid – a lack of which can lead to neural tube defects which will affect development of the baby's spinal cord and brain (and is why pregnant women are always advised to supplement folic acid)."
Southern adds that there are several other key nutrients needed for adequate development of all the vital organs, tissues, and brain, such as omega-3, protein, iron, zinc, and calcium.
"If there is a lack of these nutrients then the body will take it from the mother's stores," Southern explains. “So it's more likely that mum might start feeling weak, tired (especially with low iron), or have brain fog, as the body supports the baby's growth and development.
"There is also some evidence to show that a mother's diet might affect the baby's long term metabolism and risk of chronic diseases later in life. So if the mother is very overweight, or has issues with blood sugar regulation, this might impact on the baby's health long term and increase their risk factors for the same."
How different diets affect pregnancy
There can be benefits and setbacks to any diet you eat, be it vegan, vegetarian, or omnivore. But, whichever diet you choose to follow, it’s important that you’re consuming all of the nutrients you and your baby needs.
Some nutrients such as essential fats, B12, and zinc are all more easily found in animal sources which can also make them easier to absorb. Southern says that this can put vegan women at risk of nutritional deficiencies.
"For this reason, it's really important they ensure vegans are supplementing adequately and also getting their nutrient levels checked where possible," Southern says.
"Supporting gut health can help with ensuring maximum absorption from the food they are eating. Protein needs must also be focussed on – so ensuring a wide range of beans, pulses, nuts, seeds and tofu to ensure all amino acids are obtained. This is all something most vegans understand, but tastebuds and food choices can change when pregnant, so protein shakes might be necessary."
Southern adds that vegetarians may struggle to get adequate iron and potentially vitamin B12, but if they are consuming dairy and eggs then they should be obtaining some from their diet.
"The benefits of both vegan and vegetarian diets are often that they are really high in fibre to support gut health, low in saturated fats," Southern adds.
"Omnivore diet is my preference, and I find many of my veggie and vegan pregnant clients start to consume a little meat, or meat broth in pregnancy as often their body craves it. But of course, an omnivore diet can focus too much on meat and push out the plant based foods which are key. Again the focus should be as much as possible on a low sugar, unprocessed diet with a wide variety of foods regardless of the dietary type."
Best foods to eat during pregnancy
No matter if you eat animal products or not, Southern says the best diet to follow when pregnant is one high in whole, unprocessed foods.
"Ensure a variety of different vegetables are consumed, along with beans, pulses, and fruits to support the gut microbiome which can help support baby's immunity long term," she says.
"Eat lots of green vegetables to support natural folate, and perhaps some red meat for iron sources. Be sure to include essential fats from oily fish, nuts, seeds, avocado, and olive oil to provide DHA to support the baby's developing brain, hormones and structure."
Southern adds that regular consumption of protein is important to help support maternal blood sugar and to build amino acids that can act as building blocks to help the baby develop.
"The least supportive foods are those high in sugar, simple carbs and ultra processed foods," she says.
"However, most women go into pregnancy with really good intentions but when the pregnancy hormones kick in, especially in that first trimester, most of these foods might feel really unappetising and all you want is crisps and carbs. Don’t panic! This is normal."
Additional reporting by SWNS.
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