Why do Women Have Trouble Taking Their Prenatal Vitamins?

Tips for maximizing compliance based on 40 years of experience, and a new policy decision which could make matters worse.

Bradley Price, MD

Becoming pregnant is a significant and often long-awaited milestone in a woman’s life, and yet, a staggering number of women (almost 1 in 10 in my experience) give up on taking their prenatal vitamins completely, and many more only take them sporadically.

Why is compliance such a challenge for our patients and what can we do as healthcare providers to encourage prenatal vitamin compliance prior to, during and post pregnancy?

The ideal time to start a prenatal vitamin is weeks before conception, during “trimester 0”.

A good blood level of folic acid, a key ingredient of all prenatals, reduces risk for fetal neural tube defects, such as spina bifida and anencephaly. The neural tube closes around 4 weeks after conception, just as most women first find out they are pregnant. The key benefit of the prenatal vitamin for the pregnant woman is to prevent anemia.

Many women begin their pregnancy already iron deficient (microcytic anemia), and women physiologically boost their blood volume around 40% during pregnancy. I condense this advice for patients into my “Vitamin Pep Talk”: “The main reason to take your prenatal vitamin is to avoid a blood transfusion if you have higher than average blood loss at delivery.”

Once a patient understands the value that these vitamins can provide, it’s critical to bridge the knowledge gap to further compliance. It’s not one-size-fits-all when it comes to prenatal vitamins, and we need to help our patients to determine what works best for them. Prenatal vitamins are available in over-the-counter generic versions with 800 mcg of folate, or as brand name prescription vitamins, which contain 1000 mcg of folate, but there are a host of other differences.

Here are a few things that I consider with my patients when evaluating prenatals to ensure compliance:

  • Size: With prescription prenatal vitamins, healthcare providers have a good sense of the size and dose — versus over-the-counter products which can be all over the map. The size of the pill can greatly impact adherence: If it’s a large “horse pill”, patients will refuse to take it or have difficulty swallowing it. A well-engineered prenatal vitamin can have plenty of active ingredients and still be small in size.
  • Type of Folate: The best form of folic acid is methyl folate because it’s body-ready, the active form of the vitamin. A majority of US Hispanic women are genetically deficient in an enzyme that converts standard folate to its active form, so methyl folate could be especially appropriate for them.
  • Type of Iron: Although iron is a key ingredient in all prenatals, it is literally the hardest to stomach. Most over-the-counter vitamins contain an iron salt, such as ferrous sulfate, which is poorly absorbed, so it aggravates acid reflux and virtually guarantees constipation. Why add to her misery? A much better option for reducing these common iron side effects is ferrous asparto glycinate (Sumalate), which is much more efficiently absorbed because it’s combined (chelated) with 2 amino acids. Sumalate is not available in most over-the-counter prenatals. Remember in evaluating the iron content of a vitamin, the key is not the total dose of iron, but how efficiently it’s absorbed.

A Potential Big Bad Policy Change:

Adding another layer of complexity to the predicament of prenatal vitamin compliance, a proposed policy decision by an industry consulting group, First Databank, could drastically decrease patients’ options and access to prenatal vitamins.

This decision — which would code all prescription prenatal vitamins as over-the-counter – could greatly impact our patients on Medicaid in particular. Medicaid pays for prescription, but not over-the counter prenatal vitamins, which makes me concerned that some women may not be able to afford the over-the-counter option.

For many pregnant women and their clinicians, if prescription prenatal vitamins exit the market, it will be more and more difficult to find tolerable options. Even worse, based on my experience with other generic drugs, the fewer options in the market, the more likely there will be intermittent shortages or significant price increases.

That’s why I call this a big, bad idea.

Learn more about prenatal vitamins and how you can take action against this potential new policy here.


Dr. Price is a paid spokesperson for Avion Pharmaceuticals. He is donating all honoraria for this article to help fund contraception for low-income women.