Soy is a staple in many diets around the world yet expectant moms often hear mixed messages about it. Some people worry about hormones or GMOs. Others praise soy as a plant-based superfood. So what’s the truth?

The evidence is clear: soy can be a safe and nutritious part of a pregnancy diet. In this guide, we’ll walk you through what the research actually says. You’ll learn how soy compares to other proteins, what types of soy to prioritize, and how it can benefit both you and your baby.

Is Soy Safe to Eat During Pregnancy?

Yes—moderate soy consumption is safe during pregnancy. Large population studies in Japan, China, and Korea—where soy intake is often daily—show no adverse effects from eating soy while pregnant (PMC). U.S. dietary guidelines also recommend plant proteins like soy as part of a healthy prenatal diet.

A comprehensive 2022 technical review of over 400 human studies found no evidence that soy isoflavones disrupt thyroid function, estrogen levels, or pregnancy outcomes (PubMed). Experts now agree: soy is not an endocrine disruptor when eaten in food form.

How Much Soy Is Okay?

The sweet spot is about one to two servings per day. That could be a cup of soy milk in the morning and some edamame or tofu at lunch or dinner. Some traditional diets include even more, and studies haven’t shown harm at higher intakes. Still, extreme amounts—like combining soy shakes, supplements, and multiple soy meals every day—haven’t been well studied. Stick to whole food sources, and aim for variety.

What Are the Benefits of Soy in Pregnancy?

Soy is much more than a meat alternative. It's rich in protein, fiber, essential minerals, and beneficial plant compounds that support both your health and your baby’s development.

Soy is one of the only plant proteins that’s complete, meaning it provides all nine essential amino acids. Its protein quality (measured by PDCAAS) is on par with animal proteins like meat or eggs (PMC). For pregnant people—whose protein needs increase—this makes soy an excellent option, especially for those following vegetarian or plant-forward diets.

Soybeans are a good source of plant-based iron. While it’s non-heme iron (less absorbable than animal-based iron), pairing soy with vitamin C can improve absorption. Edamame also provides folate, which is essential for fetal brain and spine development. Just 1/2 cup of green soybeans can deliver over 100% of your folate needs (Frontiers in Nutrition).

Fortified soy milk and calcium-set tofu can be excellent non-dairy calcium sources. Soy is also naturally low in saturated fat and contains heart-healthy unsaturated fats, making it a smart swap for red or processed meats. 

Soy also helps with constipation, something that’s common during pregnancy. Fiber supports healthy digestion by feeding beneficial gut bacteria and promoting regularity (World Journal of Clinical Cases). Edamame and tempeh are great sources. They offer digestive support alongside key nutrients like protein and iron.

Does Soy Affect My Hormones or the Baby?

Research studies show that eating soy doesn’t have negative effects on a pregnant women’s health or the child in her womb.

A study in Japan looked at 194 pregnant women and found no clear link between eating soy and changes in hormone levels. Soy’s plant compounds—called Isoflavones— did show up in both the moms and their babies' cord blood. But they didn’t affect hormones like estrogen, estriol, or testosterone (Cancer Causes & Control).

As for babies, some may worry that the same compounds, isoflavones, might affect a child’s development because they act like estrogen. But these compounds are weaker than the estrogen our bodies produce. During pregnancy, the placenta filters them out, so only small amounts reach the baby. Even babies fed soy formula (which contains far more isoflavones than food sources) show no differences in growth, hormones, or development later in life (PubMed). 

There is also no consistent evidence that soy causes birth defects or affects fetal hormones. One large study found that lower soy intake, not a higher intake, was linked to a higher risk of hypospadias (a male birth defect) (PMC).

Can Soy Help Prevent Gestational Diabetes?

Emerging evidence suggests it might. Soy foods are low-glycemic and high in fiber and protein, which helps stabilize blood sugar. Multiple studies found that higher soy intake is linked to lower GDM risk (BMC Pregnancy & Childbirth). A clinical trial found that soy-rich diets improved insulin sensitivity in women already diagnosed with GDM (PMC).

While more research is needed, early findings indicate that soy appears somewhere between neutral to beneficial for blood sugar recovery during pregnancy. 

How Does Soy Compare to Other Proteins?

Soy holds its own against both animal and plant-based proteins. Compared to meat, it provides similar protein quality, but with less saturated fat and no cholesterol. Compared to other plant foods, it offers more complete protein and higher levels of minerals like iron and zinc.

Fermented soy foods (like tempeh or miso) may also enhance mineral absorption by lowering phytates, which can block absorption in beans and grains.

Are There Any Downsides?

In typical food amounts, soy is safe for most people. Here are a few things to keep in mind:

If you’re allergic, avoid soy; Chiyo provides a soy-free option on our menus for those that need to avoid soy.Keeping in mind, pregnancy doesn’t increase your risk of developing a soy allergy. Moderate soy intake is not harmful to thyroid function if your iodine levels are adequate (PubMed). If you’re taking thyroid medication, wait at least four hours before consuming soy.

Non-heme iron in soy is less easily absorbed by the body, so eat it with vitamin C-rich foods. Highly processed soy protein isolates (found in some bars and mock meats) may have lower nutrient content. Stick to whole soy foods for the best benefits.

What Are the Best Soy Foods to Eat?

Focus on minimally processed, traditional soy foods. Some good options include tofu, which is great for stir-fries, scrambles, and smoothies. Edamame is high in protein and folate, and tempeh—a fermented soy product—is rich in probiotics and iron. Fortified soy milk offers protein, calcium, and vitamin D, and miso adds flavor along with potential gut benefits.

Choose organic or non-GMO soy if that’s your preference. 

Can You Keep Eating Soy While Breastfeeding?

Yes! Moderate soy consumption is safe while nursing. Some isoflavones may pass into breast milk, but studies show no harm to infants (Karger). If your baby shows signs of allergy or sensitivity (e.g. eczema, blood in stool), consult your pediatrician. Otherwise, there’s no need to avoid soy while breastfeeding.

Final Takeaways

Soy foods are a safe, nutrient-rich addition to a pregnancy diet. They offer high-quality protein, key micronutrients, and possible benefits for blood sugar and digestion. Moderate intake—about one to two servings a day—is considered ideal.

Chiyo’s nutrition programs are designed to support every stage of the maternal journey—including pregnancy. We incorporate whole, nourishing soy ingredients like tofu, edamame, and miso into many of our meals, making it easy to enjoy their benefits with zero guesswork.

Prefer to avoid soy? We’ve got you. Our new soy-free menu is thoughtfully curated for those with allergies or sensitivities. It features delicious, nutrient-dense meals that honor your dietary needs without compromising on flavor or support. Whether you include soy or skip it entirely, Chiyo makes it easy to eat well through every stage of pregnancy.

Explore both our Prenatal Nurture Program and our new soy-free offerings to find the perfect fit for your journey.