Vegetarian and vegan diets are considered safe during pregnancy, but they require a strong awareness for a balanced intake of key nutrients.
In my practice I see women who are determined to go through their pregnancy on a vegan diet. In most cases, I have to invest quite a lot of effort in educating and explaining to these women, as they lack the basics of nutrition during pregnancy. So, I’ve decided to summarize the most important aspects of nutrition during pregnancy in this article. As there is a lot to consider, the article is split into two parts. Hopefully the articles will come handy for all pregnant readers, vegan, vegetarian or otherwise.
Weight gain and caloric needs during pregnancy
Pregnancy is not the right period for the competition of how to gain as little weight as possible. All women MUST gain weight during pregnancy. Foetal growth and infant birthweight strongly depend on this. Infant birthweight is a strong predictor of the health and subsequent development of the baby.
The recommended weight gain for a woman with a healthy pre-pregnancy weight (BMI 18.5-25) is 13-17 kg. An underweight woman (BMI<18.5) needs to gain between 14 and 22 kg. An overweight woman (BMI > 25) ideally gains 7-12 kg.
In the first trimester the weight gain is somewhere between 1.5-2 kg. In the second and third trimester the average weight gain is +/- 0.5 kg/week.
Most of the gained weight IS NOT FAT. Most of the gain is due to the increased volume of blood (2 kg), the placenta weight (0.5-1 kg), increased breast tissue (1 kg), increase in the size of the uterus and supporting muscles (1 kg), fluid volume (2 kg), and, of course, the baby weight (3-4 kg). A small amount (ideally +/- 3 kg) is stored as fat, which is used by the body during the lactation period. Lactation is a very energy-consuming function of the women’s body and requires a lot of calories.
In the first trimester of pregnancy, caloric necessities are no higher. The extra energy requirement in the second trimester is somewhere between 260-340 kcal per day, and in the third trimester it is between 450-500 kcal per day.
Protein is probably THE most important nutrient during pregnancy. Not everybody knows that all pregnant women need, on average, 25 grams of extra protein per day. Let’s pause for a moment here and remember how much protein per day we need exactly.
Under normal circumstances, a healthy omnivore (or flexitarian) should consume around 0.83 grams of protein per 1 kg of body mass per day. For example, if you weigh 60 kg, you need 60 × 0,83 = 50 grams of protein per day. However, if you’re vegetarian, you need approximately 20% more, which makes it roughly 1 g of protein per 1 kg of body mass. Therefore, if you are a 60 kg vegetarian, you need 60 g of protein per day. The guideline for vegans is 30% more than for omnivores, or 1,08 g/kg/d. This guideline is based on the fact that plant protein, on average, is digested more poorly. Thus, if you are a vegan and weigh 60 kg, you need 65 grams of protein per day. Now add 25 grams of protein to this number for pregnancy. You need exactly 90 grams of protein daily. This might sound like a challenge. If you are not sure if you get enough protein, I strongly advise you to consult your dietitian. Consulting a dietitian is always a good idea, but during pregnancy it is an absolute must (my opinion).
Basically, to cover your daily protein needs you must make sure that all your meals (breakfast, lunch, dinner and snacks) contain a significant amount of protein, which is 20-30 grams per meal.
Soy is a great source of protein, but pregnant women are discouraged to eat too much soy (see the explanation below). Other good sources of plant protein are:
- Industrially made plant-based meat alternatives.
The Nutrition Centre of the Netherlands makes a special recommendation for pregnant women. They are advised not to take too many soy products. This is because of soy isoflavones. If you ingest high doses of those during pregnancy, it may affect the development of the baby’s genitals. Convincing evidence is lacking. But this advice is given as a precaution.
How much is not too much exactly? The Nutrition Centre advises (during pregnancy) not to eat or drink more than four glasses (150 ml) of soy drink/yoghurt per day. And also, to use other soy products, such as tofu, tempeh or soybeans, no more than twice a week. So, you are still “allowed” to eat quite a lot of soy products. If you want to learn more about soy and health, please read this article.
Pregnant women are about 20 times more likely than other healthy adults to get the foodborne illness listeriosis. Even though animal-derived products are the main source of listeria, plant foods can also carry this bacterium. High-risk products are mainly long-term refrigerated products that are eaten without heating.
Raw sprouts can carry bacteria like E. coli or Salmonella. Pregnant women are therefore encouraged not to consume them or, alternatively, heat them well before consuming.