While most prenatal multis contain a cocktail of roughly 20 nutrients, the review, which looked at randomized controlled trials and was published in the Drug and Therapeutics Bulletin, reports that only two nutrients are essential to supplement to prevent birth defects and complications during pregnancy. “Pregnant women may be vulnerable to messages about giving their baby the best start in life, regardless of cost, and be unaware that the only supplements recommended for all women during pregnancy are folic acid and vitamin D,” write the U.K.-based authors.
In Canada, it’s recommended that pregnant and soon-to-be-pregnant women take a daily dose of 0.4 mg of folic acid, which is known to prevent neural tube defects, and that all women—pregnant or not—get 600 IU of vitamin D daily to support proper bone and tooth formation in infants and to help with a host of other functions. Though the UK study suggests women test their iron levels before supplementing the mineral, Health Canada recommends 16 to 20 milligrams of iron (through a daily multivitamin) during pregnancy to help women produce the extra blood their bodies need.
Health Canada also recommends pregnant women get increased amounts of everything from vitamin C to zinc, but most of those nutritional needs can be filled by food, says Deborah O’Connor, professor in the department of nutrition sciences at the University of Toronto and principal author of The Society of Obstetricians and Gynaecologists of Canada's Canadian Consensus on Female Nutrition, to be published later this year.
Prenatal multis cover off folic acid, vitamin D and iron requirements, but they also contain a long list of other nutrients. So, are you better off taking individual supplements or popping one multi that gives you everything (and more)? “Chances are there are going to be many vitamins and minerals in the prenatal supplement that you don’t need,” says O’Connor. “But it’s not going to hurt you. If you take a single supplement, you don’t have to figure it all out—because it can get quite complicated.”
Taking a prenatal multivitamin also ensures you don’t get too much of a good thing. Excess vitamin A during pregnancy, for example, can cause birth defects. The amount of vitamin A found in a daily prenatal multivitamin is entirely safe—O’Connor says you would need to take 10,000 IU in a day to cause concern.
While a balanced diet during pregnancy is the ideal, nausea and carb cravings often throw best intentions off track. In these cases, a multivitamin offers a kind of “nutrition insurance,” says Helen Van deMark, director of clinical nutrition at St. Joseph’s Healthcare Hamilton. “Depending on how you’re feeling with your pregnancy, despite your best intentions, your diet may not be as balanced and varied as you’d like it to be,” she says. So if morning sickness makes it hard to keep a green smoothie down, rest assured that a multivitamin has you covered.