Healthy Running During Your First Trimester

I’m not running Boston this year, but it has nothing to do with fear, finances, or securing a qualifying time. It has everything to do with the fact that I’m gearing up to give birth at the end of March, and apparently, running a marathon two weeks after delivery is not advisable. Who knew? And while I’m personally closer to the end of this journey than the beginning (thank goodness!), here are some tips if you’re tackling the idea of becoming a mum or going through the ups and downs of the first trimester.

This article highlights what you should and shouldn’t be eating and tips from the pros when it comes to fuelling your running and your health during the first trimester. As always, if you have additional questions, concerns and so on, turn to your doctor for more personalised and exact advice.

Here’s a brief glance into Pregnancy 101: Typical gestation takes 40 weeks but ranges from as few as 259 days to as many as 294 days (37–42 weeks). The 40 weeks of pregnancy are divided into three trimesters. These last about 12–13 weeks each (or about 3 months). This article focuses on the first trimester, which runs from weeks 1–13 (months 1–3). The second trimester runs from weeks 14–27 (months 4–6), and the third and final trimester runs from 28–40 weeks (months 7–9).

Speaking from experience, running during pregnancy is neither impossible nor easy and predictable. Luckily, during the first trimester, your gait and your weight is unlikely to change considerably (weight gain during the first trimester ranges from negligible to a few kilograms), so many runners don’t complain (yet) of the backaches or misalignment problems common before delivery. But while you might look good as you cruise along during the first trimester, you also might have to deal with other unforeseen symptoms, such as extreme fatigue, nausea and vomiting (morning sickness), food cravings or aversions, mood swings, constipation, frequent urination, and other pleasant side effects. Any of the above can affect your daily schedule, energy availability and overall willingness to get out of bed in the first place let alone lace up your running shoes.

Pregnant runners suffering from morning sickness (according to The American College of Obstretricians and Gynecologists, 70 to 85 per cent of pregnant women experience it during the first trimester) and poor fuel intake due to food aversions need to be diligent about getting in enough energy and nutrients to fuel sport, self and baby. Luckily, during the first trimester, most women only need a moderate increase of 420–1250 kilojoules per day – the equivalent of a bowl of cereal with skim milk. For runners struggling to increase food intake, try eating smaller nutritious meals and snacks throughout the day to add in a few extra kilojoules here and there. If solids don’t appeal to you, consider fruit smoothies or shakes with whey protein for additional kilojoules and nutrients.

During all of pregnancy, nutrition is of utmost importance. Tama Bloch, a prenatal nutrition expert who worked on the development of the Similac® Prenatal and Breastfeeding Supplement, recommends all expectant mothers – and especially those runners who tend to have lower stores of vital nutrients like iron – should talk to their doctor about the need to supplement their diet with a prenatal vitamin. In general, almost all pregnant women need to be taking a daily prenatal vitamin due to the need for folic acid alone.

Folic acid

Also known as folate, this vital nutrient is a B vitamin that may help prevent major birth defects known as neural tube defects. Since it can be difficult to get the recommended amount of folic acid from food alone (you need at least 400mcg/day before conceiving and 600mcg/day during pregnancy), ACOG recommends all women who are pregnant or might become pregnant take a daily vitamin containing adequate folic acid. It’s important to take in adequate folic acid before and during early pregnancy to prevent neural tube defects so don’t wait to start supplementing until you are 100 per cent certain you are expecting.


Given the fact that you are female and a runner, you already know you might be at risk for low levels of this vital nutrient, essential for maintaining energy levels because iron is needed for red blood cell health and transport of oxygen to organs and tissues. During pregnancy, your iron needs increase greatly, and during the first two trimesters of pregnancy, iron-deficiency anaemia can increase the risk for preterm labour, low birthweight babies, infant mortality, and can even predict iron deficiency in infants after four months of age. The good news is that most all prenatal supplements contain adequate iron (your basic need is 27mg/day). To further boost this intake, Bloch recommends pairing iron-fortified foods with a side of vitamin C-rich foods (vitamin C and iron have a relationship similar to that of calcium and vitamin D). If you are suffering from iron-deficiency anaemia, talk to your doc about whether you need to supplement even further, as some women have found that they need 60mg/day to resolve the anaemia.

Fibre and fluids

Prior to becoming a mother runner, you may not have given much thought to your overall consumption or timing of fibre and fluids. It’s time to think twice. During pregnancy, hormones cause a slowing of the digestive system, and you may find yourself, ahem, “running on full” many hours after eating a meal. In the fight against constipation, fibre, warm liquids and extra water are your allies. Warm liquids (such as hot water with lemon) can help to get things going – just remember to give yourself extra time to use the facilities before heading out the door. The fact that you now have a tiny person pressing against your bladder may call for you to plan your route around rest stops, but being well-hydrated is important for your health and baby’s health, too.

Vitamin D and calcium

You know that you need calcium and vitamin D daily, but did you know that your needs increase greatly during pregnancy? Your future Olympian is essentially starting from scratch and needs calcium to build every single tiny bone in his or her body. If you don’t take in extra, he or she will simply borrow from your stores and leave you somewhat depleted and at risk for injury. Aim to take in at least 1000mg/day either from supplements or better yet from calcium-rich foods, such as milk, yoghurt and calcium-fortified foods. Vitamin D is also essential for babies’ development, and more and more research suggests that this nutrient does more than help bones and teeth to grow. A recent study found that maternal vitamin D status was related to children’s strength later in life. The researchers found that mothers who had high levels of vitamin D had children with much higher grip strength compared with the children of mothers who had low vitamin D levels. The investigators also found a small but significant link between mothers with high vitamin D levels and children with increased muscle mass. So if you really are hoping for a future Olympian, think twice before skipping out on vitamin D–rich foods like fortified dairy and cereals.

Finally, now that you know which nutrients to hone in on, don’t forget which foods to steer clear of.

  • Say goodbye to your caffeine-laced chews and gels, as you’ll want to reduce your caffeine intake (most experts recommend <200mg/day) for the next 9 months.
  • Per the Dietary Guidelines (and if you ask most any doctor, anywhere) drinking during pregnancy, especially in the first few months of pregnancy, may result in negative behavioural or neurological consequences in the offspring. No safe level of alcohol consumption during pregnancy has been established.
  • While fish can be rich in lean protein and all-important omega-3 fatty acids, some varieties are high in mercury and should be avoided. Instead of shark, swordfish, king mackerel, tilefish and white (albacore) tuna (the latter of which should be limited to 170 grams a week), choose shrimp, salmon, catfish and pollock. To determine how much mercury is in your favourite seafood, check out this list.
  • Ever wonder why you can’t enjoy a cold club sandwich during pregnancy? Well, some food items – including cold deli meat – present a risk of listeriosis, a food-borne illness that can cause flu-like symptoms and lead to miscarriage, stillbirth and premature delivery. If you aren’t already, start avoiding: unpasteurised milk and foods made with unpasteurised milk; luncheon meats and hot dogs (these items are more acceptable when cooked until steaming); pates and meat-based spreads; refrigerated smoked seafood; raw and undercooked seafood, eggs and meat (i.e. no more rare steaks or sunny-side up eggs for a while please).

Until next time, happy running and gestating!

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