Macronutrient requirements in pregnancy

The diet during pregnancy should follow the same basic principles of a healthy diet, recommended for any stage of life; therefore, as an essential element, diets should be varied, the amounts to be ingested should be moderate and sufficient water consumption should be guaranteed.

The specific nutritional needs of the woman for the phase prior to pregnancy and throughout its development, should be supervised by specialists, who are responsible for evaluating and guiding in each of the scheduled consultations, the guidelines to follow to improve the nutrition of the expectant mother before and during pregnancy.

Energy needs

A healthy woman of average size and weight, with moderate physical activity requires about 2000 kilocalories per day. This figure should be increased by about 150 kilocalories per day during the first trimester of pregnancy; while in the remaining trimesters, the increase should be around 350 kilocalories per day.

For the energy needs of pregnant women to be covered in a healthy way, complex carbohydrates should provide between 50% and 60% of the total daily kilocalories needed, fats between 30% and 35% and proteins between 12% and 15%.

The extra contribution of calories during pregnancy does not need to be, as it is commonly said, "eating for two"; it would be enough to add one or two moderate daily portions of some food to the diet, selecting it depending on the nutritional needs of the pregnant woman and the caloric value it contains. For example: to increase the calcium and protein demands, the intake of whole cow's milk could be increased, taking into account that a 200-milliliter glass of milk could provide around 120 kilocalories.

Moderate increases in energy intake should be made taking into account the weight gain of the pregnant woman: when there is little or no weight gain -less than 1 kilogram per month- the caloric intake should be increased; if the weight gain is normal, it is not necessary to increase the energy intake; and if it is exaggerated, it would be convenient to reduce it. Increases and reductions in energy intake depend on the following factors:

• Body weight of the pregnant woman at the beginning of pregnancy.

• Level of physical activity performed daily.

• Weight increase related to the metabolic adaptations of pregnancy.

Protein requirements

Protein intakes in a woman's normal diet generally exceed the recommended amounts -approximately 45 grams-, which means that there are almost never problems of protein malnutrition. However, the development of maternal and fetal tissues requires a considerable protein content in the diet of the pregnant woman, which increases as the pregnancy progresses, depending on the following factors:

• The amount of protein intended for fetal development, the formation of the placenta, and the growth of the tissues of the uterus, breast, blood and adipose tissue in the pregnant woman.

• The metabolic efficiency of the pregnant woman's body, necessary to convert food protein into body structures.

• Individual variability, in correspondence to the size of the mother and the fetus.

Taking all these factors into account, an increase of 15 to 25 grams of protein per day in the diet of the pregnant woman is recommended.

Fatty acid requirements

The need for fatty acids is increased during pregnancy since, in addition to providing energy, they are involved in many processes related to the changes that occur in the mother and child. It should be noted that lipids are actively involved in the following functions:

• They are part of adipose tissue, cell membranes and the myelin sheath of nervous tissue.

• They are necessary in the formation of many hormones.

• They are involved in the absorption and transport of vitamins (A, D, E and K).

• The fatty acid docosahexaenoic acid -DHA- of the omega-3 series favors the development of the neural tissue and the retina of the creature. DHA is found in flaxseed oil, salmon, tuna, trout, shrimp and walnuts.

In general, the following types of fatty acids should be included in the diet of pregnant women:

• Monounsaturated fats -present in olive oil and nuts-.

• Polyunsaturated fats of the omega-3 series -present in the tissues of blue fish such as salmon, sardines, anchovies, tuna and mackerel; also contained in linseed, olive, canola and soybean oils-.

• Polyunsaturated fats of the omega-6 series -present in vegetable oils (sunflower, corn, soybean, etc.); walnuts and avocado-.

• Saturated fats contained in whole milk products, meats and eggs.

Carbohydrate requirements

To preserve another of the basic principles of healthy eating, carbohydrates should provide between 50% and 55% of a pregnant woman's energy needs.

At least five daily servings of carbohydrates rich in nutrients and dietary fiber are recommended, distributed throughout the day in the different meals; For example: whole wheat bread, brown rice, whole grain cereals, legumes, vegetables, tubers and fruits.

Foods that provide a lot of energy but few nutrients should be avoided, such as soft drinks, cakes, pastries, jams, excess sugar added to milk, coffee or tea.

Carbohydrate requirements rich in dietary fiber

The dietary fiber intervenes in the decrease of the intestinal transit, increases the frequency of evacuation and avoids constipation; in addition it slows down the absorption of sugars and ingested fats, which diminishes the final contribution of energy.

It has been proven that the adequate consumption of foods rich in fiber during pregnancy can reduce the following disorders related to the pregnant woman's diet:

• Constipation.

• Blood sugar spikes and thus gestational diabetes.

• The total energy intake, which avoids exaggerated weight gain.

For all these reasons, it is recommended that pregnant women consume around 35 grams of fiber daily. Foods rich in fiber are: Whole grains, legumes and raw vegetables and fruits.

Water needs

During pregnancy, a woman's water requirements increase due to the increase in plasma volume, the formation of amniotic fluid, the growth of the fetus and the loss of water and electrolytes due to the purification of waste products.

Water also prevents dehydration that can affect mother and baby, especially after vomiting and nausea. In addition, together with dietary fiber, water helps to combat constipation.

Water recommendations during pregnancy are as follows:

• Two to two and a half liters daily during the first trimester of pregnancy.

• Three liters per day from the second trimester until the end of pregnancy.