Let’s be real: navigating the world of prenatal supplements can feel like a full-time job. With all the options on the shelves and conflicting advice online, it’s tough to know what’s truly helpful—and what might actually be doing more harm than good.
As a registered dietitian specializing in prenatal nutrition, I’m here to simplify things for you. Not all forms of nutrients are created equal, and choosing the right type can make a huge difference in how you feel during pregnancy (hello, energy, sleep, and fewer side effects!).
Here’s a breakdown of the best forms of common supplements during pregnancy—and which ones to skip.
1. Magnesium
Magnesium can be a total game-changer in pregnancy—helping with sleep, muscle cramps, constipation, and stress. But the form you take matters a lot.
Yes Please:
- Magnesium Glycinate – gentle on the stomach, calming, great for sleep and leg cramps
- Magnesium Malate – energizing, supports muscles and can help with fatigue
- Magnesium Citrate – well-absorbed and helps get things moving if you’re constipated
Pass:
- Magnesium Oxide – poorly absorbed and more likely to cause diarrhea
- Magnesium Sulfate (oral) – this is not for daily use (it’s the stuff in Epsom salts or given in hospitals during labor for medical reasons)
2. Folate
Folate is critical for fetal neural tube development—and not all forms are created equal. If your prenatal contains folic acid, it’s time to look a little closer.
Yes Please:
- Methylfolate (5-MTHF) – the active form, best absorbed, and especially important if you have the MTHFR gene variant
- Folinic Acid – a great alternative to methylfolate for those who need a gentler option
Pass:
- Folic Acid – the synthetic form found in many prenatal supplements; not everyone can convert it efficiently into the usable form, especially those with MTHFR variations
3. Iron
Iron needs rise in pregnancy, but unfortunately, many common iron supplements are tough on the gut. Here’s how to choose an effective, gentle option:
Yes Please:
- Ferrous Bisglycinate – highly absorbed and gentle on the stomach
- Iron Polysaccharide – another well-tolerated option that’s easier on the gut
- Heme Iron – naturally sourced from animal products, very bioavailable
Pass / Use with Caution:
- Ferrous Sulfate – the most common form prescribed but often causes nausea and constipation
- Ferrous Fumarate / Ferrous Gluconate – slightly better than sulfate, but still may cause GI upset
- Iron Oxide – poorly absorbed and not recommended
4. Third-Party Testing
This is your non-negotiable! Supplements aren't tightly regulated, so choosing products that are third-party tested ensures safety, quality, and accurate labeling—especially crucial during pregnancy.
Yes Please:
- NSF Certified
- USP Verified
- Informed Choice / Informed Sport – especially good for athletes or active mamas-to-be
Pass / Use With Caution:
- No third-party testing listed – red flag!
- “Tested in-house” only – not independently verified, and not as trustworthy
Final Thoughts
Choosing the right supplements during pregnancy doesn’t have to be overwhelming. Stick to well-absorbed, gentle forms, and always double-check for third-party testing. And of course—run your supplement list by your OBGYN and dietitian to make sure everything is safe, appropriate, and tailored to you.
Feeling good in pregnancy isn’t just about what you avoid—it’s also about making smart, evidence-based choices that truly support your health and your baby’s development.
Disclaimer: This blog post is intended for informational purposes and should not replace professional medical advice. Always seek the guidance of a healthcare professional before making changes to your diet or supplement routine.