This article is selected from my book "Disease Nutrition".
The period from the beginning of pregnancy to childbirth is called the gestational period, and the mother undergoes a series of adjustments to provide the best growth environment for the fetus and maintain the mother's health. In addition to providing the nutrients needed by pregnant women, pregnant women must also provide the nutrients needed for the growth and development of the fetus, and the nutritional status during pregnancy determines the health status of both mother and child.
There are a number of physiological changes in the mother after pregnancy:
Endocrine and metabolic changes: the secretion of estrogen, progesterone and placental hormone increases, and the rate of increase in secretion parallels the rate of placental enlargement, which is conducive to the mother's intake of various nutrients and the healthy development of the fetus. Placental lactogen inhibits the utilization of sugars and glycogens, which may cause diabetes, T3 and T4 will increase, and metabolism will change accordingly.
Changes in the digestive system: increased progesterone secretion, relaxing smooth muscle tone, resulting in slower gastrointestinal peristalsis and indigestion and nausea and vomiting; but slowed peristalsis is conducive to the absorption of calcium, iron, vitamin B12, folic acid and other nutrients increased, which is beneficial to both mother and child.
Changes in renal function: increased glomerular filtration rate, which increased uric acid, urea, creatinine, urine sugar, amino acids, water-soluble vitamins, etc. in the urine.
The load on the main organs increases, the blood volume increases, and the load on the heart and lungs increases.
Weight gain, healthy pregnant women generally gain 10 to 12.5 kg of gestational weight. Gaining too little weight or too quickly is not good for both mother and child. The ideal weight gain during pregnancy is 1.0 to 1.5 kg in the 3 months of pregnancy, and the average weekly weight gain thereafter does not exceed 0.5 kg.
1. Nutritional requirements
1. Energy
The need for energy during pregnancy is greater than before pregnancy, but the energy intake during pregnancy should be balanced with the consumption, and too much energy will bring harm to both mother and child. The Chinese Nutrition Society recommends that the energy RNI in the middle and third trimesters of pregnancy be increased by 200kcal/day to the non-pregnant period.
2. Protein
The need for protein during pregnancy increases with the duration of pregnancy. The Chinese Nutrition Society recommends that the RNI of protein in the first trimester, second trimester and third trimester be increased by 5g/day, 15g/day and 20g/day, respectively. However, it should be noted that the supply of high-quality protein in food should account for more than 50% of the total protein throughout the day.
3. Fat
During pregnancy, it is necessary to store 2 to 4 kg of fat, and an appropriate amount of lipid intake to ensure the normal growth and development of the fetus and facilitate the absorption of fat-soluble vitamins. Lipids are an important part of the fetal nervous system, in the proliferation and growth of fetal brain cells, essential fatty acids are indispensable, and the supply of fat during pregnancy includes saturated fatty acids, n-3 and n-6 polyunsaturated fatty acids. The Chinese Nutrition Society recommends that the function of fat during pregnancy is 20% to 30% of the total energy.
4. Carbohydrates
Glucose is the only energy source for the fetus and consumes more glucose in pregnant women. The synthesis and decomposition of hepatic glycogen in the third trimester of pregnancy increases, so the demand for carbohydrates also increases, and the increase and consumption need to be balanced, such as excessive energy increase may lead to obesity and macrosomia in pregnant women, and too little fetal dysplasia and ketonuria in pregnant women. The cause of ketonuria is insufficient intake of carbohydrates, the oxidation of stored fats in the body is decomposed to provide energy, and the process of fat cannot be fully oxidized to produce ketone bodies, so the intake of carbohydrates during pregnancy should be balanced.
5. Minerals
A large amount of minerals are needed during pregnancy to meet the normal growth and development of the fetus.
(1) Calcium
The need for calcium during pregnancy is to maintain the physiological function of the pregnant woman on the one hand, and to supply the fetus with structural bones and teeth on the other hand. If calcium deficiency is severe or long-term calcium deficiency during pregnancy, it can cause osteomalacia in pregnant women and congenital rickets of the fetus. Newborns contain about 30 g of calcium in their bodies, which are obtained from the mother and used for their own development.
The Chinese Nutrition Society recommends that the AI of calcium in the first trimester is 800mg/day, the second trimester is 1000mg/day, and the third trimester is 1200mg/day.
(2) Iron
It is estimated that the amount of iron stored in pregnant women is 1000 mg for the needs of the fetus and the mother. The prevalence of anemia in pregnant women in mainland China averages 30%, so special attention needs to be paid to iron supplementation in the second and third trimesters.
The Chinese Nutrition Society recommends that iron AI be 15mg/d in the first trimester, 25mg/d in the second trimester, and 35mg/d in the third trimester.
(3) Zinc
Adequate zinc promotes fetal growth and development and prevents congenital malformations. Epidemiological data suggest that an increased incidence of fetal malformations is associated with zinc insufficiency during pregnancy. Therefore, it is appropriate to increase zinc intake during pregnancy.
The Chinese Nutrition Society recommends that the RNI of zinc be 11.5 mg/day in the first trimester, 16.5 mg/day in the second and third trimesters, and 35 mg/day in UL.
(4) Iodine
Thyroxine is important for the normal development of the brain, and iodine is an important component of the thyroid gland. Metabolism is strong during pregnancy and the need for iodine increases. Insufficient iodine, on the one hand, causes metabolic disorders and thyroid dysfunction in pregnant women, and on the other hand, affects the growth and development of the fetus, leading to the occurrence of Cretin disease. Especially in the first trimester (the first 3 months), iodine supplementation should be appropriate, which can effectively prevent ketine disease.
Recommended by the Chinese Nutrition Society. The RNI of iodine during pregnancy is 200 μg/day and the UL is 1000 μg/day.
6. Vitamins
(1) Vitamin A
The need for vitamin A during pregnancy is used to maintain the physiological and metabolic needs of pregnant women and the needs of fetal growth and development. However, vitamin A intake should be balanced, insufficient intake leads to maternal vision, skin and premature birth and other hazards, in the fetus is stunted, low birth weight and other hazards; excessive intake of poisoning leads to miscarriage, congenital malformations and so on. Excessive carotene has not been found to be toxic, so it is recommended that pregnant women supplement with vitamin A to carotene-rich foods, which can be converted into vitamin A.
RNI for pregnant women, 800 μg RE/d in the first trimester, 900 μg RE/d in the second and third trimesters, UL2000 μg RE/d.
(2) Vitamin D
Vitamin D is one of the most important regulators of calcium absorption and metabolism, so the need for vitamin D increases during pregnancy. If the deficiency leads to neonatal hypocalcemia, hand and foot twitches, infantile enamel dysplasia, and maternal osteomalacia. Vitamin D sources are food and ultraviolet rays, and vitamin D deficiency is prone to occur in areas with cold and little light all year round, so it needs to be supplemented from diet, such as marine fish, animal liver, egg yolks, etc.
The RNI of vitamin D during pregnancy is 10 μg/day and UL20 μg/day.
(3) Vitamin B1
Pregnant women have a strong metabolism, the need for vitamin B1 increases, vitamin B1 is stored in the body for a short time, and it is necessary to constantly supplement from the diet, so it is necessary to pay attention to the adequate amount of supplementation in the diet.
The RNI of vitamin B1 during pregnancy is 1.5 mg/day.
(4) Vitamin B2
Vitamin B2 is involved in the body's metabolism, enzyme composition and other functions, if it is lacking during pregnancy, it will affect the growth and development of the fetus.
The RNI of vitamin B2 is 1.7 mg/day.
(5) Folic acid
The increased need for folic acid during pregnancy, if absent, can lead to megaloblastic anemia and fetal neural tube malformations, so it is important for pregnant women to supplement, it is recommended to start folic acid supplementation in the first 3 months of pregnancy.
The RNI of folic acid during pregnancy is 600 μg DFE/day and UL1000 μg DFE/day.
(6) Vitamin C
Vitamin C has a promoting effect on the growth and development of the fetus, the soundness of the hematopoietic system, and the body's immunity. Vitamin C deficiency during pregnancy can lead to miscarriage or premature birth, and the fetus is predisposed to scurvy and anemia after birth.
The AI of vitamin C during pregnancy is 100 to 130 mg/day.
Second, common nutritional problems and prevention
1.Pregnancy vomiting
After pregnancy, due to metabolic changes, progesterone secretion increases, so that smooth muscle tone decreases, gastrointestinal peristalsis function slows down and nausea, vomiting, dizziness and fatigue and other early pregnancy reactions, if vomiting is frequent and intense, eating decreased or can not eat leading to malnutrition and other hazards occur.
2. Nutritional anemia
The prevalence of anaemia during pregnancy is 30%. Nutritional anemia during pregnancy includes iron deficiency anemia and macroloblastic anemia caused by folate and vitamin B12 deficiency, mainly due to insufficient intake of iron, folic acid, vitamin B12 and other nutrients.
3. Gestational diabetes mellitus
The incidence of gestational diabetes mellitus is about 1% to 3%. After pregnancy, the pregnant woman endocrine changes, placental lactogen secretion increases, inhibition of sugar and gluconeogenesis, in addition to factors such as the pregnant woman's own health status or a family history of diabetes.
4. Hypertension in pregnancy
Factors that occur in pregnancy-induced hypertension include obesity in pregnant women, a high-sodium diet, and inadequate intake of vitamin B6, zinc, calcium, magnesium, protein, and other nutrients. PREGNANCY is characterized by hypertension, edema, proteinuria, convulsions, coma, and heart and kidney failure.
4. Dystrophic edema
Inadequate protein intake during pregnancy can lead to dystrophic edema, and can occur when vitamin B1 is severely deficient.
Any nutritional problems during pregnancy are harmful to both mother and child, and some harms are irreversible, so they should be scientifically prevented. The Chinese Nutrition Society recommends that women of childbearing age begin to adjust their nutritional status and living habits 3 to 6 months before planning pregnancy to prepare for a successful pregnancy.
A reasonable diet during pregnancy should be adjusted with the physiological changes in pregnancy, the timing and the growth and development of the fetus. On the one hand, the supply of all nutrients needed by pregnant women should be balanced, and each nutrient should be adjusted with the growth and development of the fetus; on the other hand, the nutrients should be balanced between them so as not to lead to malnutrition.
Dietary recommendations during pregnancy:
1. First trimester, first trimester
(1) Food diversification, daily diet should include cereals and potatoes, animal foods, milk, beans and their products, vegetables and fruits, etc., in the same kind of food can be alternately eaten, not only to achieve dietary diversification, but also to achieve nutritional complementarity of each food.
(2) Start to supplement folic acid 3 months before pregnancy, and consume foods rich in folic acid, such as animal liver, soybeans, eggs, spinach, cabbage, red amaranth, peas, tomatoes, etc., to prevent neural tube malformations. Folic acid preparation supplementation can be carried out with 400 μg daily from the first 3 months of pregnancy to the entire duration of pregnancy.
(3) Often eat iron-rich foods, because pregnant women themselves reserve iron and fetal growth and development need iron, pregnant women's iron deficiency directly leads to nutritional anemia, which brings harm to both mother and child. From the first 3 months of pregnancy to the entire pregnancy should often eat iron-rich foods, such as animal liver, animal whole blood, livestock and poultry lean meat, fish, black fungus, red dates, etc., while eating vitamin C-rich foods, such as fresh vegetables, fruits to promote iron absorption.
(4) Often eat foods rich in calcium, calcium plays an important role in the development of fetal bones and teeth, calcium deficiency not only affects the development of the fetus, but also leads to osteomalacia in pregnant women. Foods rich in calcium, such as milk and dairy products, stone snails, river prawns, hair vegetables, black fungus, etc.
(5) Often eat iodine-rich foods, cooking food during pregnancy with iodized salt, and appropriately increase the intake of seafood, such as kelp, seaweed, marine fish, sea cucumbers, etc.
(6) Adequate energy intake during pregnancy to meet the needs of maternal nutrition and fetal growth and development, by increasing the amount of staple foods and appropriate fat intake and increasing meat food to achieve, and the ketone body produced by insufficient carbohydrate intake has an impact on fetal brain development.
(7) The diet in the first trimester is light and delicious, such as the first trimester with serious reactions, you need to eat less and more meals.
(8) Develop good eating habits, pay attention to dietary hygiene, eat less salty, too sweet and greasy food, do not eat stimulating foods, and maintain a pleasant mood.
2. Second trimester
(1) The intake of high-quality protein should be appropriately increased in the second trimester, such as the supply of fish, poultry, eggs, lean meat and other foods. The fetus enters a rapid growth period at the beginning of the second trimester, the reproductive organs of pregnant women gradually develop, and pregnant women reserve energy and nutrients for postpartum lactation, so the amount of food needs to be increased in the middle and third trimesters. Animal high-quality protein food, fish also contains omega-3 polyunsaturated fatty acids, which are extremely important for fetal brain and retinal development, so fish is the first choice, the best intake 2 to 3 times a week; eggs are a good source of lecithin, vitamin A, vitamin B2, and should also be often used.
3. Middle and third trimesters
(1) Increase in food in the middle and third trimesters of pregnancy, but it is necessary to pay attention to preventing weight gain too quickly, which can easily lead to gestational diabetes and fetal oversized hazards. Therefore, BMI should be controlled within a reasonable range according to pre-pregnancy weight control during pregnancy.
Whether it is the first trimester, the second trimester or the third trimester, under the condition of physical permission, as far as possible, outdoor activities, mainly walking. And keep a good mood and get enough sleep.