The Best Prenatal Vitamins: How to choose a Prenatal

Choosing a prenatal vitamin can be daunting! There are so many options online and on drugstore and health food store shelves. Some of you may have been given a prescription for a prenatal vitamin from your doctor. The truth is that prenatal vitamins run the gambit from pretty basic and thus omitting important nutrients to very comprehensive to somewhere in between.

First of all, it’s important to note that the purpose of a prenatal vitamin is to fill in any gaps in your diet to ensure that you and baby are adequately meeting nutrient needs. I subscribe to a food first philosophy meaning the prenatal vitamin is a fallback when your diet falls short, sort of like insurance to make sure your nutrient needs are met when your eating is less than ideal. That being said, it’s important to avoid the mentality that the prenatal vitamin can fix a nutrient poor diet – while it certainly can help, a prenatal vitamin is not a cure-all. Nutrients that occur together in food likely act synergistically, so deriving nutrients from food is optimal. Because of the difficulty in maintaining a consistently nutrient dense diet, I recommend my clients take a prenatal vitamin while trying to conceive, pregnant, and post-partum. This begs the question as to what makes a quality prenatal vitamin. Here are some of the things I look for when choosing a prenatal vitamin:

1) Contains methylated folate instead of folic acid. Most prenatal vitamins contain folic acid, which is a synthetic and stable form of folate. Both prevent neural tube defects, however if you have MTHFR (methylene tetrahydrofolate reductase) polymorphism, you don’t convert folic acid into the active form of folate as easily. Up to 50% of the population may carry at least 1 copy of this polymorphism, and most people don’t get tested to learn if they do. When you take methylated folate in your prenatal vitamin, you are getting the form that is active in your body. It’s also important to make sure you’re getting enough folate from food while trying to conceive and pregnant.

2) Contains at least 150 mcg iodine. The American Academy of Pediatrics recommends women take a prenatal vitamin containing 150 mcg iodine daily. Iodine is an essential nutrient for thyroid function and 37% of American non-pregnant women of childbearing age don’t get enough iodine.1 Iodine is essential for mom’s thyroid function, and a sluggish thyroid during pregnancy can negatively affect baby’s brain development. Vegetarians and vegans who don’t eat fish or dairy products are at especially high risk for iodine deficiency. In one study, 44% of women tested had mild to severe iodine deficiency when starting to TTC. Women with moderate and severe iodine deficiency took longer to conceive than women who were iodine sufficient or had only mild iodine deficiency.2

3) A vitamin B12 source, ideally in the methylcobalamin form instead of the standard cyanocobalamin form. If you a vegetarian or vegan, having B12 in your prenatal vitamin is especially essential. Vegans have no dietary B12 sources, as B12 only comes from animal products. Vegetarians will have more limited vitamin B12 intake. Low blood levels of serum vitamin B12 even in the normal range have been associated with higher risk for miscarriage and lower pregnancy and live birth rates compared to women with higher B12 levels in women doing IVF.3

4) Contains 1000-2000 IU vitamin D. Vitamin D levels in the normal range have been associated with higher pregnancy rates via IVF.4 In addition, vitamin D is essential for bone health and hormone balance and may restore menstrual cycle regularity in women with PCOS who are vitamin D deficient. Baby’s vitamin D stores come from mom, so if mom is vitamin D deficient during pregnancy, baby will likely not get enough. If you’ve found a good prenatal vitamin that’s short of on vitamin D, you can always add additional vitamin D. Please note that for many 1000-2000 IU vitamin D is not enough during pregnancy or while TTC, so it’s important to have your vitamin D level tested, as this can help guide you to know how much additional vitamin D you need.

5) Contains choline. There is evidence to suggest that choline helps prevent neural tube defects like folate/folic acid.5 The adequate intake for choline is 425 mg for adult females and increases to 450 mg during pregnancy. Most women are not getting enough choline, especially during pregnancy. Adding on a stand-alone choline supplement is an option if your prenatal vitamin doesn’t contain any or has only a limited amount.

6) Contains less than 5000 IU preformed vitamin A, such as retinyl palmitate. Excessive levels of preformed vitamin A in pregnancy can cause birth defects. This limit does not apply to beta-carotene or carotenoids, which do not have this effect in pregnancy.

While this list doesn’t cover every situation and every possible nutrient, these are some of the main things I look for when evaluating a prenatal vitamin. Always remember that a prenatal vitamin is not a substitute for a healthy and nutrient dense diet.

References

1. Linus Pauling Institute at Oregon State University: Iodine.

2. Mills JL, Buck Louis GM, Kannan K, et al. Delayed conception in women with low urinary iodine concentrations: a population-based prospective cohort study. Hum Reprod. 2018; 33(3): 426-433.

3. Gaskins AJ, Chiu Y, Williams PL. Association between serum folate and vitamin B-12 and outcomes of assisted reproductive technologies. Am J Clin Nutr. 2015;102:943-950.

4. Ozkan S, Jindal S, Greenseid K, et al. Replete vitamin D stores predict reproductive success following in vitro fertilization. Fert Stert. 2010; 94(4):1314-1319.

5. Linus Pauling Institute at Oregon State University: Choline for Neural Tube Defect Prevention.