It’s true what they say: when you’re pregnant, you really are eating for two. But that’s not a free-for-all to order double shake shack burgers, rather an opportunity to pay close attention to what you’re putting in your body. What mama eats nourishes baby, too. And during these nine months, one of the most important things you can put in your body is iron.

A diet rich in iron is crucial for developing babies. Your body uses iron to make red blood cells, which carry oxygen to your baby. During pregnancy, your blood volume increases by about 40 to 50 percent – meaning you need those additional red blood cells more than ever.

Good iron levels are important for your wellbeing, too, keeping your already exhausted body from working harder than it needs to.

“In pregnancy, per se, your kidneys and your heart are already working a little bit harder because you’re pregnant, and we wouldn’t want to add insult to injury,” Dr. Tamika Auguste, Associate Professor of Obstetrics and Gynecology at Georgetown University School of Medicine, said. “We want to optimize your health during pregnancy. It’s almost like, making sure you’re running on a full tank of gas.”

To keep you from running on empty, the American Congress of Obstetrics and Gynecology recommend pregnant women get 27 milligrams of iron a day.

You can find high amounts of iron in dark leafy greens like spinach and kale, legumes, nuts and seeds, red meat, and tofu. A quarter of a block of tofu, for example, contains 6.2 milligrams of iron (let’s be honest, who only eats one quarter of a block of tofu?), while a cup of lentils contains 6.6 milligrams. An eight-ounce steak contains about the same.

About a quarter of all women -- 15 to 25 percent -- become iron deficient during pregnancy, according to the American Pregnancy Organization, so it’s important to watch out for red flags. If you look in the mirror and pull your lower eyelid down and the skin that’s supposed to be pink is pale: that’s called conjunctiva pallor, and Dr. Auguste says it can be a sign of iron deficiency. Another sign is exhaustion, but aside from a few glorious weeks in the second trimester, exhaustion is pretty ubiquitous for most mamas-to-be.

So if you think you might be iron deficient, one way to give yourself a quick check at home is to check the capillary refill under your fingernails. Press your nail and if it doesn’t go back to pink right away, you might need more iron.

“Sometimes when iron levels are extremely low, there’s a disorder that develops called pica, and women tend to crave ice sometimes, sometimes they crave dirt, sometimes they crave detergent or baking powder,” Dr. Auguste said. “So when a clinician has a patient that comes in with a big tall 20 oz. cup of ice and they’re just chomping away, I would be like – let’s check your iron levels.”

If you have dietary restrictions that could impact your pregnancy, like if you’ve needed extra folic acid in the past or if you are vegan, you should let your physician know. If that’s not the case for you, a balanced diet and your prenatal vitamins should keep you running on all cylinders.

And if those prenatals turn your stomach, Dr. Auguste says no problem. “Sometimes the prenatal vitamins can be hard to swallow, so I tell my patients go ahead and take a Flintstone’s vitamin.”

Photography by Hanna Nakano.