Congratulations! You’re pregnant! And, of course, you are very concerned about your health and the health of your child. Almost everyone agrees that nutrition during pregnancy is important, but one of the overlooked benefits of eating an optimal diet during pregnancy is that a child’s taste for food begins in the womb.
Your diet during pregnancy and breastfeeding will influence your baby’s taste for foods when solids are introduced. Another benefit of optimal nutrition is that you will be in great shape and prepared for the demands of motherhood by the time you deliver your baby, too!
So, what should you eat? The same well-structured, low-fat, plant-based diet I recommend to everyone, with more calories. It takes between 60,000 and 80,000 calories to grow a baby, which is about 250-300 extra calories per day during the 2nd and 3rd trimester. Many women make the mistake of overeating, thinking they are “eating for two”, which while technically true is not a free pass to over-consume. Weight gain of over 25 pounds is not advisable since this increases the risk of many conditions including pre-eclampsia and gestational diabetes. Additionally, excess weight gain increases the size of the baby, making vaginal birth difficult or impossible.
Many doctors recommend dietary supplements for pregnant women, particularly folic acid. It is true that folic acid has been shown to reduce neural tube defects, which result in decreasing deformities of the spinal cord in half. But the benefit concerning risk reduction is expressed in relative rather than absolute terms, which is quite misleading. The risk of neural tube defects for women who do not take folic acid supplements is 2 in 1000. For women who do take them, the risk is about 1 in 2000. This is, indeed a 50% reduction in relative terms, but only a 1% reduction in absolute terms. The actual reduction in risk of neural tube defects as a result of taking folic acid during pregnancy is actually 1%, not 50%. On the other hand, there are risks associated with taking folic acid supplements, including an increased risk of cancer.
There really is no need for women who eat a well-structured plant-based diet to take folic acid supplements. Folic acid comes from folate, which is found naturally in plants. Pregnant women can take in adequate amounts of folate through diet and do not need to take it in supplement form.
There are concerns about taking other supplements during pregnancy also. For example, a study that looked at the effects of Vitamins C and E on pre-eclampsia in high-risk women showed that the vitamins had no effect, and the women taking them had lower birth weight babies.
Calcium supplements are also not recommended. A developing fetus requires about 30 grams of calcium for normal development, which is approximately 2.5% of a woman’s stored calcium. During pregnancy, a woman’s body adapts, increasing absorption and retention of calcium, and decreasing urinary excretion of calcium. To be fair, most doctors are prescribing prenatal vitamins and other supplements to pregnant women because they know that most people do not eat an optimal diet, and it’s the best option based on their training. However, the uncertainty about both the safety and efficacy of supplements makes eating a plant-based diet comprised of whole foods the better choice.
The one exception may be B12. Women consuming an exclusively plant-based diet and no fortified foods should take a B12 supplement.
Vegetarians or vegans are not at risk of iron deficiency, contrary to popular belief. A woman’s body stores 2.2 grams of iron, and only 1 gram of extra iron is needed during pregnancy; an extra 5 mg per day, which is easily met while consuming a plant-based diet. At the end of the first trimester, absorption of iron from foods increases – up to 9.1 times the normal rate of absorption, another adaptation designed by nature to facilitate proper development of the fetus.
Remember that pregnancy is not a disease, but a natural and (for most) an enjoyable process that can be made easier with an optimal diet and a good exercise program. It’s a time to focus on your health and your baby’s health in preparation for a most wonderful adventure!
1. Mennella, JA, “Prenatal and postnatal flavor learning by human infants”, Pediatrics, 2001 June; 107(6):E88
2. Black M, Sacks D, Xiang A, Lawrence J. “The Relative Contribution of Prepregnancy Overweight and Obesity, Gestational Weight Gain, and IADPSG-Defined
Gestational Diabetes Mellitus to Fetal Overgrowth” Diabetes Care January 2013 vol. 36 no. 1 56-62
3. Ebbing, M, Bonaa K, Nygard, O et al. “Cancer Incidence and Mortality After Treatment With Folic Acid and
Vitamin B12.” JAMA. 2009;302(19):2119-2126.
4. Poston L “The Vitamins in Pre-eclampsia Trial.” The Lancet (DOI:10.1016/S0140-6736 (06) 68434-1)
April 10, 2017
You are reporting the results of this study in relative rather than absolute terms which exaggerates the benefit of taking the supplement. See my article for an explanation of this; when real numbers are used the benefits of drugs and supplements often disappear.
April 1, 2017
Interesting! I’m taking a plant based over the counter prenatal and all my blood work is good. My doctor knows I eat a mostly plant based diet yet she still recommends I continue with my prenatals AND add an iron supplement. After reading this I’m considering taking my prenatals every other day instead of daily. What should I do? I’m almost 28 weeks.
April 10, 2017
It would be inappropriate for anyone to give you advice specific to your situation without knowing more about you and your medical history. The best option is to consult with a health professional who will review published scientific data with you so that you can make an informed decision. Many of my articles are designed to show the risks associated with just doing what you are told by medical professionals.
July 30, 2013
Great info here but you should know that a new study out of Norway has shown that pregnant woman who take folate/folic acid have reduced the amount of children born with autism by almost 50%.