The energy required during pregnancy varies considerably from person to person. This reflects wide differences in the body's energy needs and the amount of exercise performed. For most women, the extra calories required are not huge - only some 100 to 300 calories per day.

In women who substantially reduce their exercise, the need for extra calories may be minimal. Even towards the end of the pregnancy only 2400 calories daily are needed by the average woman (where 2100 calories daily are the average for non-pregnant woman).

While few extra calories are required during pregnancy, there is a greater demand for extra nutrients. It is important to choose nutrient-dense foods, and to avoid high fat, and calorie-dense foods such as biscuits, confectionery and soft drinks.

Vitamin/mineral supplementation, particularly of iron, folic acid and zinc is usually prescribed as a safeguard.

During pregnancy both the developing fetus and the mother have nutritional needs. It is important to ensure that your intake of vital nutrients is covered by a healthy diet. However, most pregnant women do not meet their nutritional needs through diet alone and find that a vitamin and mineral supplement is necessary.

There are many supplements designed specifically for pregnant women. Talk to your health care provider about the right supplement for you.

The following is a guide to some of the most important nutrients that may require supplementation:

Calcium: Inadequate calcium intake during pregnancy can increase a woman's risk of developing osteoporosis later in life. It is therefore important to ensure that your calcium intake is adequate throughout pregnancy and the period during which you are breastfeeding.

It is recommended that pregnant women have a calcium intake of 1200 mg per day.

You may find that you have an adequate calcium intake from your diet if you include two or more servings of dairy foods per day. However, you may require a supplement - discuss your needs with your doctor.

Folate: Folate is helpful in preventing neural tube defects (NTDs), such as spina bifida, in newborn babies. Seventy percent of cases of NTDs can be prevented by women increasing their intake of folate to 0.5 mg per day at least a month before conception and in the first three months of pregnancy. The timing is essential because NTDs occur in the first few weeks of pregnancy, when the baby's brain and spinal cord are forming.

Folate is a form of a water-soluble B vitamin. It occurs naturally in many foods. Folic acid is the synthetic version of folate and is found in supplements and fortified foods.

There are three ways of increasing your folate intake:

• Eat foods that are rich in folate.
• Include foods in your diet that have been fortified with folate, such as breakfast cereals.
• Take a folic acid supplement. Don't rely on your normal multivitamin to provide the required daily amount of folate as most supplements only contain minimal amounts.

Good sources of folate include green leafy vegetables, fruits including citrus fruits, berries and bananas, legumes and some fortified cereals.

Iron: During pregnancy, extra iron is required for the increase in the mother's blood volume and for the normal growth of the fetus and placenta. Since it can be difficult to get the recommended amounts of iron from food, a daily supplement may be prescribed. The extra iron promotes adequate stores in the mother's body to be used during breastfeeding. An iron supplement may also be beneficial in combating fatigue.