How to Choose a Prenatal Vitamin

Choosing a prenatal is one of the first of many decisions mums-to-be make, and it isn’t an easy one. The ingredient list can be confusing, the pills themselves are large, and they come in a bewildering variety. A search on Amazon yields 507 hits for “prenatal vitamins,” plus there are direct-to-consumer brands. Though there are a core set of nutrients that are the same across all prenatals, some have more of certain ingredients, others have ingredients beyond those that are required, and many have different chemical structures of the nutrients. To make your prenatal vitamin selection go down easier, here are a few factors experts recommend considering.

Who should take a prenatal vitamin?

Ideally, you should begin taking a prenatal vitamin before you become pregnant, says Emily Oken, M.D., a professor of nutrition at the Harvard TH Chan School of Public Health. “Most of the nutrients we require are increased during pregnancy, so it’s helpful for all women to take a prenatal vitamin and mineral supplement to add to the nutrients we get in our diet,” says Marie Caudill, Ph.D., a professor of nutritional sciences at Cornell University.

DHA, iodine, choline, and biotin: not in every prenatal, but worth considering

Fish is an important source of docosahexaenoic acid (more commonly called DHA), says Emily Oken, M.D., a professor of nutrition at the Harvard TH Chan School of Public Health. She advises women to eat two servings per week of high DHA, low-mercury fish like trout, salmon, or sardines. If the thought of fish is turning your stomach, “then there is absolutely no harm from [supplementing with a prenatal containing] DHA,” Dr. Oken says.

Fish also contains iodine, which Dr. Oken says is a common deficiency in the U.S., and can result in thyroid dysfunction and cognitive and developmental delays in kids. She recommends choosing iodised salt, and also taking a prenatal vitamin that contains 150 micrograms of iodine, an ingredient Dr. Oken says is only found in about half of prenatal vitamins.

Choline and biotin are also not found in every prenatal, but Dr. Caudill recommends both. “Choline is noted for its role in brain and eye development,” Dr. Caudill says, and biotin is also required for fetal growth. She says they’re “under the radar” nutrients because there’s a lot of new research about them and they haven’t yet made the prenatal vitamin recommendation lists. Beyond those, Dr. Oken advises women to discuss with their healthcare provider whether they have specific needs, “For example a woman might require more iron based on a blood test that indicates anemia, or more vitamin D if their blood test shows they are insufficient.”

B12 and folate: in every prenatal in different forms

While vitamin B12 is in every prenatal, it’s especially important for women with vegetarian or vegan diets, because it’s naturally found in animal products. Dr. Oken explains that “low B12 levels have been associated with poor fetal growth, preterm birth, and some birth defects.” Look for a prenatal that contains at least 2.6 micrograms of B12. Dr. Caudill additionally recommends a methylated form of vitamin B12, which is the “bioactive” form most readily used by the body.

Dr. Caudill says choosing the bioactive form of a nutrient is always a good idea, except when it comes to folic acid. Folic acid is the only form of folate with robust evidence supporting its effectiveness in reducing neural tube defects, like spina bifida. “Other forms [of folate] might reduce neural tube defects as well, but we don’t have the evidence,” Dr. Caudill explains.

Some vitamin companies have been replacing folic acid with L-methylfolate, citing concerns about common variations in a gene involved in the folate pathway. Stuart Shapira, M.D., Associate Director for Science and Chief Medical Officer for the CDC’s National Centre on Birth Defects and Developmental Disabilities, says folic acid has been shown to reduce neural tube defects even in women with these gene variations. “If women with or without [common variants in the MTHFR gene] consume the recommended 400 milligrams of folic acid every day, then they will all have a level of folate in the blood that is adequate to help protect their pregnancies from having a neural tube defect,” says Dr. Shapira.

Folic acid is especially important before and during early pregnancy, because the neural tube closes between the fourth and sixth week of pregnancy — even before many people can find out they are pregnant. “I think anyone that is planning a pregnancy should consider taking a prenatal so they have everything on board to support that pregnancy… and continue through the end of lactation,” says Dr. Caudill.

How much is too much?

When it comes to amounts of each nutrient, more is not better. “There’s no need for a vitamin to be providing more than 100% of the recommended amount for a pregnant woman. By providing too much of a given nutrient it can create imbalance,” Dr. Caudill says. However, the recommendations vary slightly between expert organisations, like the FDA and the American College of Obstetricians and Gynecologists (ACOG). For instance, the FDA recommends 800 micrograms of folic acid, which is twice as much folic acid as ACOG advises.. But ”there’s no reason for a prenatal to have 1,000 micrograms of folic acid in it,” Dr. Caudill says. That would be 250% of your daily value, according to ACOG’s recommendation.

What to expect

Should those giant pills have a big price tag? “Prenatal vitamins should not be very expensive. There are common generic brands that contain all of the recommended nutrients,” Dr. Oken explains. But Dr. Caudill says it might be worth stretching your budget for a prenatal vitamin with bioactive ingredients, and that includes “extras” like choline, biotin, and iodine. “But a prenatal vitamin at the lower end is going to benefit you more than not consuming one at all,” she says.

Prenatal vitamins sometimes have another price to pay: they can cause symptoms like nausea or constipation, “mostly because of the iron,” Dr. Oken says.. “If that is the case, [a person] might try taking it at a different time of day, or avoiding consuming first thing in the morning when they are likely to be more nauseated.” Before lunch, she says, is often a good time for taking them.

Narrowing it down

“Most important is for a woman to discuss with her doctor what her needs might be based on her own health,” Dr. Oken says. Ask your doctor if they have any recommendations based on lab work or your diet, and if price is a concern, ask for a prescription (if that makes them more affordable through your health plan). If you don’t eat much fish, a vitamin with DHA and iodine could be beneficial. Based on the latest research, everyone might want to consider a supplement that includes choline and biotin. If your budget allows, the more expensive bioactive forms of each nutrient might be better absorbed by your body, with the exception of folic acid, which an abundance of research has shown is safe and effective for preventing birth defects. And don’t let your research take too long — a prenatal vitamin is beneficial when taken well before pregnancy.