Do women need to eat for two in pregnancy?

Most people are familiar with the phrase, ‘You’re eating for two,’ related to pregnancy. We don’t know when it was first used to justify a second serving of dinner or snacking on treats that once might have been saved for special occasions.

In reality, this idea is not true. While a woman’s nutrient needs are much higher during pregnancy, her total energy requirements only increase slightly.

Nutrient needs during pregnancy

In fact, during the first trimester (3 months) of pregnancy, women do not require any extra energy from food. The Australian National Health and Medical Research Council says that energy requirements then only increase in the second trimester (3 to 6 months) by approximately 330 kcal (1400 kJ) per day. This is equivalent to one tub of low-fat yoghurt, plus one cereal bar and one piece of fruit.

During the third trimester (6 months until birth), women require an extra 450 kcal (1900 kJ) per day. This is equivalent to a bowl of cereal with milk plus a cheese sandwich. However, there is an increased need for many important nutrients during pregnancy (protein, folate, calcium, iron, zinc, iodine and fibre).

To meet the high nutrient demands of pregnancy, a wide variety of different nutrient-dense foods, rather than energy-dense foods, should be chosen.

A nutrient-dense food contains high levels of many nutrients such as protein, minerals and vitamins in each gram of food; an energy-dense food provides high levels of food energy (kJ/g) but may be quite poor in nutrients.

Healthy food choices can be found in the five food groups: vegetables, fruit, cereals and whole grains, lean meat (or meat alternatives) and dairy.

Here’s a quick guide to the best sources.

• Protein: meat, chicken, seafood, dairy products, legumes and grains, nuts, eggs.
• Folate: bread and breakfast cereal that has been fortified with folate, green leafy vegetables, legumes, seeds, nuts, oranges.
• Calcium: dairy foods, fortified soy drinks, green leafy vegetables, nuts, seeds such as sesame, canned fish with bones.
• Iron: red meat, fortified cereals, egg yolks, green leafy vegetables, legumes, nuts.
• Zinc: meat, eggs, seafood, nuts, tofu, miso, legumes, wheat germ, whole grain foods.
• Iodine: canned salmon and tuna, other fish, oysters, bread fortified with iodine.
• Fibre: wholemeal and wholegrain bread, high fibre cereals, oats, vegetables and fruit with the skin on.

Energy needs during pregnancy

Total energy requirements during pregnancy depend on many factors including physical activity. While energy is required to support the growth and development of a new life and the development of the woman’s own maternal tissue, women compensate for their additional demands by slowing down, becoming less active and metabolically efficient.

Can you eat too much?

Eating too much while pregnant can lead to excessive weight gain and an increased risk of pregnancy complications. It also makes it more difficult for a mother to return to her pre-pregnancy weight.

The best way to determine whether a pregnant woman is consuming adequate energy is to monitor her weight gain or to have her dietary intake assessed by a registered dietitian.

So the phrase, ‘You’re eating for two’ is definitely only a myth. Energy requirements do not change in the first trimester and they only increase by about 15% towards the end of pregnancy. On the other hand, nutrient requirements do increase substantially during pregnancy. Meeting these requirements requires a varied, healthy diet.

If the mother does not have a healthy diet, shifts in how nutrients are metabolised during pregnancy can enable the healthy growth and development of the baby and maternal tissue, but the mother’s health can suffer (for example, if the mother’s diet is lacking in calcium, the baby will get calcium from the mother’s bones).

What about supplements?

Prenatal supplements can assist with the delivery of nutrients in cases of deficiency but these should always be taken under medical supervision. Excessive intake of some supplements can cause damage to the baby.

Overall, the key to the pregnancy diet is nutritious high-quality food, not merely increasing food quantity.

Find out more

You can access links to further information about healthy eating during pregnancy or while breastfeeding.