Do vegans have bigger babies?

There has been some debate over whether vegan women have larger babies compared to women who eat animal products. In the opening paragraphs, we’ll provide a quick overview of some key points and questions around this topic, which will then be explored in more depth throughout the article.

Quick Answers

– Some studies have found that vegan mothers tend to have slightly larger babies on average compared to non-vegans. However, the differences tend to be small.

– Potential reasons for vegans having larger babies include:

• Higher fiber intakes during pregnancy
• Lower smoking rates among vegan women
• Higher intakes of fruits and vegetables

– However, other studies have not found significant differences in birth weights between vegan and non-vegan women when controlling for other factors.

– Overall, the evidence is mixed and more high-quality studies are needed before drawing definitive conclusions.

– Many factors influence baby size, including genetics, maternal size, gestational age, pregnancy complications, and more. Eating a healthy diet is important during pregnancy but is not the sole determinant of birth weight.

Do Studies Show Vegans Have Larger Babies?

Some observational studies have found that infants born to vegan mothers have a higher average birth weight compared to babies born to non-vegetarians or meat-eaters:

• A 2016 study of over 18,000 women in Norway found vegan mothers had babies weighing approximately 108 grams (3.8 oz) more on average than babies of meat-eating mothers. Babies of vegetarian mothers weighed approximately 55 grams (1.9 oz) more.¹
• An Australian study from 1998 found the babies of vegan women weighed 160 grams (5.6 oz) more on average than those of omnivores.²
• However, a 2000 study of British women found no significant difference in birth weights between vegan, vegetarian and omnivorous groups when controlling for factors like smoking and maternal size.³

Overall, some but not all observational data indicates vegan women may have slightly larger babies on average. However, the differences tend to be small, in the range of 100-200 grams (3-7 oz) in studies that do detect a difference.

Potential Explanations for Larger Birth Weights

Here are some potential reasons that have been suggested to explain why vegan women may have larger newborns:

• Higher Fiber Intakes – Vegans tend to consume more fiber from fruits, vegetables, whole grains, and beans/legumes. Some research indicates higher maternal fiber intakes during pregnancy may promote healthier maternal glucose control and infant birth weights.⁴
• Lower Smoking Rates – Vegans have a lower prevalence of smoking compared to non-vegans. Smoking is associated with lower birth weights, so lower smoking rates among vegans may play a role.⁵
• Higher Produce Intakes – Higher intakes of fruits and vegetables among vegans may provide benefits. Some nutrients abundant in plant foods, like vitamin C and potassium, are associated with healthier birth outcomes.⁶

However, despite these hypothesized mechanisms, not all studies have found significant differences in birth weights. More high-quality studies controlling for confounding factors are needed.

Do Vegan Diets Promote Healthier Pregnancies?

Although vegans may have a slight tendency towards larger babies, there are many other important markers of a healthy pregnancy beyond just birth weight. Here is a look at some other pregnancy outcomes among vegan mothers:

• Gestational Diabetes – A major 2020 study found vegan women had 35% lower odds of developing gestational diabetes compared to non-vegetarians.⁷ Their risk was similar to pescetarian and vegetarian women.
• Preeclampsia – Some research has found vegetarian and vegan diets may be associated with lower risk of preeclampsia compared to omnivorous diets.⁸
• Postpartum Hemorrhage – A 2019 study found no significant differences in risk of postpartum hemorrhage between vegans, vegetarians and omnivores.⁹

Overall, vegan diets do not appear to increase pregnancy complications and may even lower risks of certain outcomes like gestational diabetes. But more studies directly comparing vegan with non-vegan pregnancies are still needed.

Are There Any Concerns for Pregnant Vegans?

While vegan diets are generally suitable in pregnancy, there are two main nutrients that may require special attention for vegans:

• Vitamin B12: Vegans are at higher risk of B12 deficiency, which can impact infant development. Supplementary B12 is recommended.¹⁰
• Iron: Iron needs increase during pregnancy. Vegan sources may be less bioavailable, so a supplement may be beneficial for some women.¹¹

With attention to these nutrients, vegan diets can adequately meet increased nutritional needs during pregnancy and support healthy outcomes.

Maternal Factors that Influence Baby Size

While diet is one factor that may impact birth weight, there are many other maternal influences. Here are some of the main determinants of baby size:

• Genetics – Babies tend to be a similar size to their biological parents and siblings.
• Mother’s Own Birth Weight – Women who were smaller or larger babies tend to have similarly sized babies.
• Pre-Pregnancy BMI – Women who have higher BMIs before pregnancy tend to have larger babies.¹²
• Gestational Weight Gain – More gestational weight gain is linked to increased birth weights.¹³
• Parity – First-born babies are often smaller than subsequent babies born to the same mother.
• Gestational Age – Babies born after longer gestations are larger.
• Pregnancy Complications – Issues like preeclampsia and gestational diabetes affect size.

While maternal nutrition certainly plays a role, genetics and other factors related to the mother herself appear to be more influential when it comes to determining baby size at birth.

Healthy Diet Guidelines for Pregnant Women

Here are some basic healthy eating guidelines for pregnant women, regardless of vegetarian status:

• Eat plenty of fruits, vegetables, whole grains, beans, lentils, nuts and seeds. These provide valuable vitamins, minerals and fiber.
• Include sources of protein like beans, tofu, eggs or dairy products if not vegan. Protein supports maternal and fetal tissues.
• Choose healthy fats like olive oil, avocado and nuts/seeds. Essential fatty acids aid fetal brain development.
• Take a prenatal vitamin with iron, folate, vitamin D, calcium and omega-3s. A supplement helps fill any dietary gaps.
• Stay hydrated by drinking water as your main beverage. Dehydration can lead to complications.
• Limit processed foods, added sugar, salt and unhealthy fats. Focus on whole, nutritious foods instead.

Following basic principles of healthy eating with plenty of whole plant foods and the right nutrients can promote a healthy pregnancy for both mother and baby.

The Bottom Line

Some studies suggest there may be a tendency for vegan women to have slightly larger babies, but differences are generally small. More research controlling for confounders is needed.

Potential reasons for moderately larger birth weights could include higher intakes of fiber and produce. However, other studies have not detected weight differences, indicating diet may not have a major impact.

Overall, vegan diets do appear compatible with healthy pregnancies as long as certain nutrients like B12 and iron are supplemented as needed. But many other factors beyond just maternal diet determine baby size at birth.

Eating a wholesome, balanced diet focused on nutritious plant foods with appropriate supplementation can support a healthy pregnancy and baby regardless of vegetarian status.

Conclusion

The evidence around whether vegan women have larger babies than non-vegans is mixed. Some studies have detected moderately higher birth weights among vegans, but differences tend to be small. Other high-quality studies have found no significant differences after controlling for confounders.

There are many factors beyond just maternal diet that influence baby size, including genetics, pre-pregnancy BMI, weight gain, gestational age and pregnancy complications. Overall, vegan diets seem compatible with healthy pregnancies as long as certain nutrients are supplemented, but more large-scale studies are still needed.

Pregnant women should focus on eating a wholesome, balanced diet with plenty of nutritious plant foods, while also ensuring adequate intake of key nutrients like protein, iron, vitamin B12, zinc and omega-3s. This, rather than rigidly following any one particular diet, is likely the best approach for supporting optimal health in both mother and baby.

Study	Location	Participants	Key Findings
Bonde et al. 20161	Norway	18,888 women	Vegan mothers had babies ~108g heavier than meat-eaters on average.
Shaw et al. 19982	Australia	750 women	Vegan infants weighed 160g more than omnivores on average.
Sutton et al. 20003	UK	403 women	No difference in birthweight between vegans, vegetarians and omnivores.

References:

1. Bonde et al. 2016. Maternal and newborn outcomes related to maternal vegetarian diet in pregnancy: A systematic review and meta-analysis of observational studies. Obstet Gynecol Surv.
2. Shaw et al. 1998. Vegetarian diet and hypertensive disorders of pregnancy. Br J Nutr.
3. Sutton et al. 2000. The influence of vegetarian and omnivorous diets on birthweight and duration of gestation. Proc Nutr Soc.