The best technique to determine if the nutrients are being appropriately delivered is to compare the nutrients needed during pregnancy with the result of the measurement of their plasma levels.
However, the hemodilution inherent in pregnancy, along with the ease with which particular nutrients travel to the fetus, makes determining the nutritional status of pregnant women extremely challenging. As a result, the needs of non-pregnant women are used as a starting point, and results from studies of nutrient consumption in women who have had healthy infants with appropriate development are incorporated.
What are the Nutrients needed during Pregnancy?
The total amount of nutrients needed during pregnancy is roughly 70,000 kcal, or 260 kcal per day. The remaining 40% is attributable to an increase in basal metabolism and the additional energy required to move a bigger body.
This does not imply that food consumption should be raised in equal proportion during pregnancy (we should not “eat for two”) because metabolic adaptation allows for improved nutrient utilization and the mother’s physical activity reduces in general.
An excess of nutrients needed during pregnancy causes a rise in fat deposits and a larger weight in the infant, as well as an increased risk of postpartum obesity in the mother. A lack of nutrients, on the other hand, leads to low birth weight babies who suffer from higher neonatal morbidity and mortality.
The recommendations range from a 200 kcal/day increase advised by British institutions exclusively in the third trimester to a +300 kcal/day increase recommended by the WHO throughout the pregnancy.
How to determine the Nutrients needed during Pregnancy?
A thorough technique to determine the nutrients needed during pregnancy based on the constitution, nutritional status, optimum weight, basal energy consumption, and physical activity expenditure has been developed.
- Women with a pre-pregnancy weight of less than 90% of their ideal weight should receive a supplement of 350–450 kcal/day;
- Women with a pre-pregnancy weight of between 90–120% of their ideal weight should receive a supplement of 200 kcal/day;
- Women with a pre-pregnancy weight greater than 120% of their ideal weight should receive a supplement of 100 kcal/day.
- Women who weigh less than 80% of their optimum weight or more than 135% of their ideal weight require a complete assessment of their needs and should visit a professional to determine their best diet.
Protein Consumption during Pregnancy
During pregnancy, the mother produces around 950 g of protein to support the fetus’s growth and tissue change. The increased protein demands are projected to be +1.3 g/day during the first trimester, +6.1 g/day during the second, and +10.7 g/day during the third trimester.
Excessive protein consumption can be hazardous to the fetus since it has been shown that when protein intake surpasses 25% of total calories, infant weight declines dramatically and the rate of preterm births and neonatal deaths rises.
Lipid Requirements during Pregnancy
The amount of lipids that a pregnant woman should consume is unknown, however it is known that necessary fatty acid consumption is critical.
Essential fatty acids can pass the placenta and contribute to fetal cell division and brain development. A sufficient supply of essential fatty acids is required for the development of the placenta, the baby, and the overall result of pregnancy.
A supply of 3% of energy in the form of linoleic acid and 0.5% in the form of – linolenic acid enables proper development of maternal and fetal cells.
Similarly, omega-3 and long-chain fatty acids are critical for neural structure creation.
Carbohydrate Requirements during Pregnancy
Carbohydrate consumption should account for 50-55% of total calorie intake and is critical for keeping maternal blood glucose levels stable. The fetus’ primary source of energy is glucose, and 50% of maternal glucose consumption during pregnancy is intended for the fetoplacental unit.
This puts the mother at risk of hypoglycemia, especially during fasting periods. Fasting for more than 6 hours may dangerously drop the levels of glucose, insulin, and neoglycogenic amino acids in the blood while increasing the amounts of ketone bodies, which may harm the fetus.
Conversely, the reduced intestinal motility and proclivity to pregnancy produce constipation, which can be addressed with an appropriate fiber diet of at least 35g/day.
Mineral Requirements during Pregnancy
Micronutrient requirements during pregnancy are increased even more than calorie requirements, emphasizing the importance of eating nutritionally dense meals (providing many micronutrients per kcal).
Birth abnormalities and development retardation are caused by mineral and vitamin deficits.
Calcium Requirements during Pregnancy
Because of higher levels of 1,25 (OH)2 cholecalciferol, calcium metabolism is fundamentally changed during pregnancy due to a series of hormonal changes that result in enhanced absorption and retention of the mineral.
The fetus’ calcium requirements are greatest at the end of pregnancy and are fulfilled by maternal bone stores. Thus, the kid accumulates calcium at a rate of 7 mg/day in the first trimester, 110 mg/day in the second trimester, and 350 mg/day in the third trimester. This mineral’s consumption should be increased by 600 mg each day, according to the guidelines.
Recent research, on the other hand, has linked low calcium levels to an increased risk of prenatal hypertension, and calcium supplementation in pregnant women with high blood pressure may help avoid the development of preeclampsia and eclampsia.
Iron Requirements during Pregnancy
Iron requirements during pregnancy are higher due to increased blood volume, placental expansion, and fetal need; however, losses due to menstruation, the major method this mineral is lost in women of reproductive age, vanish, hence it is not suggested to increase iron consumption during pregnancy.
However, because iron deficiency is the most common nutritional disease worldwide, and many women face pregnancy with iron deficiency deposits, even if it does not manifest clinically as anemia, it is necessary to control the levels of this mineral, because maternal hyposideremia has been linked to an increased risk of prematurity.
Because the relationship between hemoglobin levels and the risk of gestational issues has a U-shape, both excessively low and high values are associated with a higher risk of preterm and low birth weight in the infant.
Iodine Requirements during Pregnancy
According to the Convention on the Rights of the Child (1989) and the World Conference on Micronutrients (1992), “every child has the right to an adequate iodine intake to ensure normal neurological development,” or, more specifically, “every child has the right to an adequate iodine intake to ensure normal neurological development.”
“Every woman has the right to appropriate iodine consumption in order to guarantee enough thyroxine secretion for her child’s optimal neurological development.”
Iodine is an essential mineral for the synthesis of thyroid hormones, which participate in the metabolism of various macronutrients and thus in the processes of cell division and general development, but especially in the formation of the Central Nervous System, participating in neuronal migration towards the cortex and correct myelination of neurons.
Maternal T4 levels in embryonic fluids are high from the start of gestation, and thyroxine is transformed into T3 in the cerebral cortex of the fetus, where it performs its role; by mid gestation, the fetus synthesizes its own thyroid hormones, although maternal hormone transfer is still significant.
The hormonal changes during pregnancy stimulate the thyroid gland, resulting in greater iodine filtration via the kidneys. As a result, the demand for iodine to meet the requirements for optimal thyroid hormone production rises.
Iodine deficiency can cause congenital hypothyroidism with severe mental retardation, dwarfism, and deafness in the most severe cases; however, many studies have shown that subclinical iodine deficiencies during pregnancy have a negative effect on the subsequent psycho-intellectual development of children or that children born in iodine deficient areas have a lower IQ than those born in iodine sufficient areas and increase the cases of hyperactivity and attention.
For these reasons, 220 g/day is a suggested Iodine consumption during pregnancy, which frequently necessitates the use of pharmaceutical supplements.
Zinc Requirements during Pregnancy
Zinc is vital for life because it is a cofactor of various enzymes, some of which are involved in nucleic acid replication. Plasma zinc levels fall beginning with pregnancy and continue to fall until birth, reaching a level 35% lower than in non-pregnant women.
A lack of zinc in the first trimester has been linked to fetal malformations, and a lack of zinc in the third trimester has been linked to low birth weight, as well as complications during delivery: placenta previa, premature rupture of membranes, inefficient contractions, and a prolongation of the expulsion period.
It is consequently recommended that zinc consumption during pregnancy should be increased by +5 mg per day. Zinc supplements can interfere with copper absorption, hence in the event of pharmacological supplementation, both minerals must be provided at the same time.
Despite the increase in the needs of all vitamins, with the exception of folic acid and in exceptional cases of vitamin D, the requirements of both water-soluble and fat-soluble vitamins are covered with an adequate diet and it is not necessary to take polyvitamin supplements.
During the perinatal period the vitamin is important for fetal growth and there is a high placental transport; deficiency of this vitamin is associated with prematurity and intrauterine growth problems.
However, high doses of this vitamin have been associated with congenital malformations, therefore it is not recommended to increase the intake of this vitamin, remaining at 800 µg/day.
All forms of vitamin D are transported to the fetus via the placenta and its deficiency during pregnancy is associated with problems in calcium metabolism in mother and child: osteomalacia, neonatal hypocalcemia with altered muscle function (tetany) and low birth weight.
The intake of 10 µg/day of this vitamin reduces the incidence of hypocalcemia in the neonate and doses of 25 µg/day increase the gain in height and weight of children during postnatal life.
Adequate exposure to sunlight is as important as dietary intake, so it should not be forgotten that walking outdoors, receiving sunlight on the face and forearms, at least for 10 minutes every 3 days and without sun protection factor is enough to prevent deficiencies in this vitamin.
The recommendations for vitamin E consumption during pregnancy are increased by 25% with respect to those of non-pregnant women, an increase based on the need for the vitamin to stimulate fetal growth.
The greatest placental transfer to the fetus occurs during the last quarter of gestation, so premature newborns are usually deficient in this vitamin, which increases the risk of suffering hemolytic anemia, due to an increase in oxidative processes in these children.
Pyridoxal phosphate concentrations are lower in pregnant women than in non-pregnant women, while the fetus maintains very high plasma levels due to high protein metabolism. High intakes of this vitamin are necessary to prevent the decrease in plasma levels, which are sometimes difficult to obtain from the diet alone.
Although they are not sufficient to prevent vitamin B6 plasma depletion, it has been shown that intakes higher than 1.9 mg/day (+0.6 mg/day) do not produce any benefit for mother or newborn.
Several studies have shown that vitamin C insufficiency is teratogenic as well as a cause of premature rupture of membranes.
Women who smoke or drink alcohol regularly, or who have taken contraceptives for a long time, may have diminished deposits of this vitamin and are recommended to take ascorbic acid supplements. In any case, the requirements of pregnant women are 80 mg/day (+20 mg/day) due to fetal needs.
Folic acid is essential for growing tissues. Folic acid requirements during pregnancy are the highest of all vitamins due to the rise in maternal blood volume, the development of the placenta, and the expansion of the uterus and fetus.
Because of the rapid development rate of the neural tube, the moment when the most of this vitamin is required is when this structure is forming. Thus, enough folate consumption has been shown to prevent the development of neural tube abnormalities like as anencephaly (lack of skull development) and spina bifida.
It is recommended that pregnant women increase their intake from 400 g/day to 600 g/day during the entire gestation period in order to avoid the occurrence of megaloblastic anemia as well as other gestational defects such as heart and limb malformations, premature births, low birth weight babies, miscarriages, and pre-eclampsia/eclampsia.
To avoid neural tube abnormalities, the US advises an 800 g/day folate consumption during pregnancy, which is extremely difficult to accomplish with food alone.
Because the neural tube develops between days 24-27 of gestation, the development of a neural tube abnormality is predetermined from the start of gestation.
Given that a woman’s menstrual cycle is not delayed until more than fourteen days after conception and that it normally takes a few days for her to visit her doctor to evaluate her status, identifying pregnancy early enough to begin folic acid supplementation is quite challenging. Folic acid supplements should thus be administered before to conception to provide appropriate folic acid levels at the moment of neural tube closure.
This would not be a problem if all women were under medical supervision before conception and all pregnancies were planned, but this is not the case in more than half of the cases, so some countries have resorted to fortification of certain foods (in the United States, 140 g/100 g of cereal is added to flour) since 1998, and a clear decrease in the incidence of these embryonic malformations has been observed.