Both vegetarian and vegan diets are safe and can meet nutrient requirements with the supplementation of vitamin B12.[i] According to the Vegetarian Position statement of the Academy of Nutrition and Dietetics (formerly known as the American Dietetic Association) “Well-designed vegetarian diets, that may include fortified foods or supplements, meet current nutrient recommendations and are appropriate for all stages of the life cycle, including pregnancy, lactation, infancy, childhood, and adolescence.”[ii]
This confirms a large amount of human experience and anecdotal evidence from vegetarians and vegans the world over. In fact, neonates born to vegetarian, especially vegan, mothers from developed countries, have higher birth weight and lower prevalence of low-birth-weight compared to nonvegetarian mothers.[iii]
See Dr Esther Park-Hwang, Ob/Gyn, talk about nutrition requirements during pregnancy and how a plant-based diet can give health advantages to pregnant women:
Vegetarian pregnancies also carry some health advantages. For instance vegans seem to have a lower risk of preeclampsia. The risk of preeclampsia in the general population is about 3%.[iv] However, in a study of 775 vegan pregnancies, only one case of preeclampsia was noted,[v] giving a rate of only about .01%. Other less specific studies have shown decreased risk with higher consumptions of fruits and vegetables. In a Norwegian study, women with high scores on a dietary pattern characterized by vegetables, plant foods, and vegetable oils, were at 28% decreased risk of preeclampsia for the highest tertile vs. the lowest tertile.[vi] Vegetarians also experience a lower risk of excessive gestational weight gain. For instance in one study, vegetarians had a reduced risk of excessive gestational weight gain of 54%.[vii]
Early concerns were expressed about the birth defect hypospadias (a congenital malformation in which the opening of the penile urethra occurs on the ventral side of the penis) in association with vegetarian diets. However, this has turned out to be unwarranted according to a large study.[viii] Other concerns raised over the use of soy phytoestrogens also seem to be unwarranted. According to one study, higher intake of some phytoestrogens was associated with reduced risks of delivering infants with hypospadias, even after adjustment for several covariates. This finding applied to overall intake of phytoestrogens as well as intake of specific phytoestrogens, so phytoestrogens may actually be protective of hypospadias.[ix]
For the pregnant adolescent or adult vegetarian, if assessment of iron, calcium, zinc, EPA, and DHA intake or status reveals a potential deficiency, or lower than optimal concentration, based on clinical judgment, the patient should be counseled to increase intake of foods rich in these nutrients, adding foods that were fortified with them, and or taking supplements.[x]
[i] Pawlak R., Parrott S.J., Raj S., Cullum-Dugan D., and Lucus D. “How prevalent is vitamin B12 deficiency among vegetarians?” Nutr Rev 2013; 71: pp. 110-117
[ii] Cullum-Dugan D, Pawlak R. “Position of the academy of nutrition and dietetics: vegetarian diets.” J Acad Nutr Diet. 2015 May;115(5):801-10.
[iii] Drake R., Reddy S., and Davies J. “Nutrient intake during pregnancy and pregnancy outcome of lacto-ovo-vegetarians, fish-eaters and non-vegetarians.” Veg Nutr 1998; 2: pp. 45-52
[iv] Hutcheon JA1, Lisonkova S, Joseph KS. “Epidemiology of pre-eclampsia and the other hypertensive disorders of pregnancy.” Best Pract Res Clin Obstet Gynaecol. 2011 Aug;25(4)
[v] Carter JP, Furman T, Hutcheson HR. “Preeclampsia and reproductive performance in a community of vegans.” South Med J. 1987 Jun;80(6):692-7.
[vi] Anne Lise Brantsaeter “A Dietary Pattern Characterized by High Intake of Vegetables, Fruits, and Vegetable Oils Is Associated with Reduced Risk of Preeclampsia in Nulliparous Pregnant Norwegian Women.” J Nutr. 2009 Jun; 139(6): 1162–1168
[vii] Alison M. Stuebe et. al. “Associations of diet and physical activity during pregnancy with risk for excessive gestational weight gain” Am J Obstet Gynecol. 2009 Jul; 201(1)
[viii] . Carmichael SL. “Nutritional factors and hypospadias risks.” Paediatr Perinat Epidemiol. 2012 Jul;26(4):353-60.
[ix] Suzan L Carmichael “Hypospadias and Maternal Intake of Phytoestrogens.” Am J Epidemiol. 2013 Aug 1; 178(3): 434–440.
[x] Cullum-Dugan D, Pawlak R. “Position of the academy of nutrition and dietetics: vegetarian diets.” J Acad Nutr Diet. 2015 May;115(5):801-10.