If you're pregnant, the odds are that your obstetrician has prescribed prenatal vitamins or recommended you buy them over-the-counter. Prenatals are expensive, so it's tempting to use them even if they've expired. However, while the won't become toxic, they will probably be less potent after the expiration date, meaning you shouldn't use them.
Prenatal Vitamins
Prenatal vitamins aren't fundamentally much different than regular womens' multivitamin and mineral supplements. They do have more folic acid and more iron, but otherwise contain the regular assortment of vitamins and minerals you'd find in a garden-variety daily supplement. The extra folic acid assists with formation of the neural tube, which becomes your fetus's spinal cord and brain, while the extra iron assists in formation of extra blood cells, explain Drs. Michael Roizen and Mehmet Oz in their book "Biochemistry."
Expired VItamins
Prenatals, like other vitamins, don't become toxic when they expire. They do lose some of their potency, however, explains MayoClinic.com. This means that while the bottle may say you're getting 100 percent of your required vitamin C, if you take expired vitamins, you're getting something less than that--and it's impossible to say how much. This makes it difficult to determine whether you're actually meeting your nutritional needs.
Vitamins Versus Minerals
Prenatal vitamins contain both vitamins and minerals. The minerals--calcium and iron, for example--don't really change as they age. The vitamins, however, can change significantly. The most sensitive of the vitamins are the antioxidants, including vitamin C. These vitamins react with air and a multitude of other substances, and are quite reactive in nature. They're also the vitamins that protect you from environmental toxins and cancer-causing substances, so you don't want to be deficient in them.
General Guidelines
Generally speaking, you should throw out prenatals when they're past their printed expiration date. That said, if you're close to finishing a bottle, there's no reason not to finish the last few days--or even weeks--of pills if the expiration date passes while you're in the process of finishing up your supply. If you have leftover prenatals from a prior pregnancy, however, and are hoping to use them for a future pregnancy in coming years, it's best to restock when the time comes.
References
- "You: Having A Baby"; Michael Roizen, M.D. and Mehmet Oz, M.D.; 2009
- MayClinic.com; Dietary supplements: Nutrition in a pill?; June 2010
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