Should Your Prenatal Contain Iron? Why We Left It Out

The short answer

• Iron is one of the most important nutrients in pregnancy, but the dose you need depends on your blood results, which is why it works best as a standalone supplement rather than a fixed amount in a prenatal.
• Iron and zinc compete for absorption, so combining them in the same capsule works against both.
• Iron is absorbed best when it's taken every second day rather than daily, which is something a daily prenatal can't offer.

If you've read the label on Prenatal Support [Her], you'll have noticed that iron isn't on it, and that tends to surprise people because iron is one of the first nutrients anyone mentions in pregnancy. It is a big deal, and that's exactly why we chose to leave it out. As nutritionists, we would much rather see iron dosed properly to your levels than added to a prenatal at a fixed amount that's a guess for most women.

Why does iron matter so much in pregnancy?

By the third trimester you're carrying close to 50% more blood than you were before you conceived, and every one of those extra red blood cells needs iron, while your baby is building up the iron stores that will carry them through their first few months after birth. Your iron needs rise as your pregnancy goes on, especially in the second half, which is why the recommended intake during pregnancy is 27mg a day compared with 18mg beforehand.

A study shows nearly one in five women in their first trimester already had low iron. Low iron can leave you feeling exhausted, breathless and foggy, and it's something your GP or midwife will want to treat properly rather than simply top up.

Why doesn't iron belong in a prenatal?

Putting iron in a prenatal is counterintuitive once you look at how the body actually absorbs and uses it, and there are a few reasons we feel strongly about this.

Everyone starts in a different place

Some women go into pregnancy with healthy iron stores, while others are already low before they've had a positive test. A fixed amount in a prenatal is too little to correct a true deficiency and more than someone with healthy stores needs, which is why Australian guidance doesn't recommend routine iron supplements for every pregnant woman and focuses on testing and treating instead.

Iron and zinc compete for absorption

These two minerals are absorbed through overlapping pathways in the gut, and research published in the American Journal of Clinical Nutrition found that iron supplements reduced how much zinc people absorbed. Zinc plays an important role in cell growth and your baby's development, and Prenatal Support [Her] contains 30mg of it, so we didn't want iron sitting in the same capsule and working against it.

Iron is absorbed best every second day

Each dose of iron prompts your liver to release a hormone called hepcidin, which slows iron absorption for roughly 24 hours. In a 2020 study of women with iron deficiency anaemia, iron taken every second day was absorbed around 40 to 50% better than a dose taken the day after another, which is why we recommend taking iron as a standalone supplement every second day rather than daily. A prenatal, by design, is something you take every day.

Iron can be hard on your stomach

Nausea and constipation are the most common complaints with iron supplements, and a large review of 43 trials found the most common form, ferrous sulfate, more than doubled the odds of gut side effects compared with a placebo. On top of first-trimester nausea, a prenatal that makes you feel worse is much harder to take consistently, and consistency is what makes a prenatal work.

What we recommend instead

• Get your bloods done early. Ask for a full blood count and ferritin before you start trying or at your first antenatal appointment. Ferritin reflects your iron stores, and a level under 30 is commonly used as the cut-off for deficiency in pregnancy.
• Keep checking throughout your pregnancy. Standard care often waits until around 28 weeks for a second check, but we recommend checking your iron regularly before that point, so that if your levels start to drop you can target it early and much more effectively.
• If you're low, take iron as a standalone supplement every second day. Take it a couple of hours away from your prenatal, pair it with something high in vitamin C such as orange juice, kiwi fruit or strawberries, and keep it away from tea and coffee. Your GP, midwife or nutritionist can help you choose the right dose.
• Support it with food. Red meat, chicken and fish contain the form of iron your body absorbs most easily, and lentils, beans and leafy greens add to your intake, especially alongside a vitamin C-rich food like capsicum or a squeeze of lemon.

Where Prenatal Support [Her] fits in

Leaving iron out of Prenatal Support [Her] was a deliberate choice. It covers the nutrients you need every day, including methylfolate, 600mg of choline, iodine and vitamin D, and leaves iron to be taken separately at the dose your blood results call for. If your levels are healthy, you're not taking iron you don't need, and if they're low, you can take a targeted dose every second day without it competing with your zinc.

Iron is too important to leave to a fixed dose, so get your levels checked regularly and let your results guide how much you take.

This is general information only. Please speak with your GP, midwife or healthcare practitioner about your iron levels and what's right for you.