Pregnancy is one of the most beautiful experiences in a woman’s life time. The whole family anxiously looks forward for the birth of a beautiful and healthy baby. The baby is the fruit of her life- a life giving birth to another life. Couples often plan their babies but a large percentage of pregnancies in India are unplanned. Lifestyle and nutrition during pregnancy is often of great concern, but the preparation and care done before in pre-pregnancy or pre-conception period is critical because it lays a strong foundation for a healthy pregnancy without any problems or complications, and a favorable and successful pregnancy outcome.
Conception begins with the fertilization of the ovum by the sperm to form a zygote. After fertilization, cell division occurs very rapidly and forms a blastocyst which is implanted in the inner lining of the uterus i.e. the endometrium. Thereafter the embryo is formed followed by the formation of different organs and tissues, each of which have specialized functions. Growth and development of all of these continue throughout. Good maternal nutrition is imperative at every stage of pregnancy, everyday being important.
Oxygen and nutrients are reached to the foetus through the umbilical cord. The umbilical cord also picks up the waste from the foetus and gets rid of through the mother’s body via the placenta. The placenta is a special organ that is formed which connects the mother and foetus. It synthesizes many important compounds including hormones that are important for maintaining the foetus and ensuring a healthy pregnancy. Hence placenta is can be called the foetal life line.
The entire period of 9 months of pregnancy is divided into three trimesters each having typical features that are shown in the table.
Table Typical features of each trimester of pregnancy
|Typical features||I Trimester||II Trimester||III Trimester|
|Periods in each trimester||Conception to 12 weeks||13 – 28 weeks||28-40 weeks (birth)|
|Expected gestational weight gain (Kg)||0.6- 1.0||3.0-3.5||6.0-8.0|
|Changes occurring in pregnant woman||Missed menstrual periods
Risk of morning sickness, Possibility of headache
Food cravings/ aversions or pica (craving for eating non-food items like mud, chalk)
Frequent urination, Constipation
Weight loss or gain or no change may occur
|Some women may experience general aches and pains
Darkening or itching of the skin in some sensitive parts of body
|More pressure on abdomen may cause some discomforts in women in walking, sleeping, bowel movement
|Changes occurring in the foetus||Formation of all major organs and tissues particularly the neural tube, spine and brain begin to form
Formation of eyes
Development of blood vessels
|Bone marrow begins to make blood cells.
Facial features appear
Taste buds appear on tongue.
Footprints and fingerprints are formed.
Hair growth begins on head.
Lungs are formed, but do not function yet
Sexual organs begin to form
At 11 weeks all organ systems are functioning
|Kidneys begin to function and make urine
Fine hair begins to grow on the head
a protective waxy coating on the whole body (vernix) develops
Foetus gains weight steadily, body fat increases.
and is getting bigger
Limbs are fully formed with finger nails and toenails
Baby’s organs begin to function, although lungs and kidneys are fully mature.
Baby may turn into a head-down position for birth.
Stretch marks on skin
|Crucial micronutrients needed during each trimester||DHA, iron, calcium, folic acid, vitamin D, protein||DHA, iron, calcium, folic acid, vitamin D, vitamin A, vitamin B6, choline, vitamin B12, protein||DHA, iron, calcium, copper, zinc, magnesium, folic acid, vitamin D, vitamin A, vitamin B6, choline, vitamin B12, protein|
Physiological Changes during Pregnancy
- Generally, in a well-nourished mother, body weight is increased by about 8-12 Kg in 9 months of pregnancy. GWG is comprised of weight of the foetus, amniotic fluid, placenta as well as the weight gain of the maternal tissues like uterus and deposition of adipose tissue. Weight gain usually occurs in the second and third trimesters. It is greatly influenced food and nutrient intake, level of physical activity and medical condition (if any). Low weight gain increases the risk of intrauterine growth retardation (IUGR) and mortality of the foetus or neonate.
- There is about 45-50% increase in blood plasma volume for the formation of new red blood cells (RBC) and to facilitate oxygen and nutrient supply to the foetus and for newly formed maternal tissues. This is one of the causes of natural fall in the haemoglobin level (by 1-2 mg/100ml) causing anaemia in pregnant women if additional iron and protein intake is low.
- There is increased oxygen demand for tissue development is naturally compensated by improved efficiency of lungs, cardiac output and increased BMR.
- Gastro intestinal motility is slowed down which is advantageous to allow more time for absorption of the nutrients. This improves absorption of iron, calcium, vitamin B12 and other nutrients.
- Renal functions are also altered in order to excrete metabolic wastes of both mother and foetus and sodium retention increases.
Nutritional status of the pregnant woman is often governed by the numerous factors.
Nutritional Requirements during Pregnancy
Nutritional requirements during pregnancy are different in the three trimesters and vary with age, body weight, body size; dietary pattern and nutritional status of the mother during her adolescence and pre-pregnancy period.
Energy: Energy cost of pregnancy (kcal) relates to the energy deposited in the form of tissue deposition, gestational weight gain and increase in BMR. It is much higher need of energy in 2nd and 3rd trimesters that relates to the additional need of 350 kcal/d and 600 kcal/d respectively. Since energy needs as recommended by Indian Council of Medical Research and National Institute of Nutrition (ICMR-NIN, 2020) for a woman is according to activity pattern that is sedentary, moderate, and heavy activity and a healthy woman require 1660, 2130 and 2720 kcal/d. when the same woman gets pregnant additional energy needs can be added, e.g. a office going pregnant woman would require 2010 kcal/d in second trimester and 2260 kcal/d in third trimester.
Protein: A normal woman need 45.7g of protein per day. During second trimester additional protein requirement would be 9.5 g/d that will be 55g/d and in third trimester it will be 67.5g/d. Additional protein intake will take care of the physiological changes occurring in the body such as expansion of blood volume and protein deposition in foetus, uterus, and placenta and breasts; for the formation of new cells, enzymes, hormones, antibodies, muscles, collagen, skin, blood, bones etc.
At the same time, protein, and energy ratio (PE ratio) is also important. Protein quality of the foods consumed is equally important but protein supplements during pregnancy are not advisable as they disturb the PE ratio and there may be adverse consequences.
Fat: A pregnant woman is required to consume 30g fat/d. Besides quantity of fat intake, the food sources and quality of fats are extremely important. Hence it is necessary to ensure adequate intake of DHA and long chain polyunsaturated (LCPUFA) is crucial for the foetal development of brain and retina. Fat plays important role in functions and formation of the cell membranes, hormones, and other biological compounds. Omega-3 fatty acids also play a role in determining the length of gestation, maturation of organs. Experts suggest consumption of 100-200mg DHA per day, to support optimal pregnancy outcome.
Micronutrients: Supply of micronutrients from the peri-conceptional period throughout pregnancy is crucial. Requirements for most vitamins and minerals are increased significantly. Adequacy of iron, folate, and vitamin B12 are very crucial at the time of conception and throughout pregnancy for RBC production and sustained cell division for enlargement of uterus, growth of placenta and foetus. Increased requirement of B- vitamins like thiamine, riboflavin, niacin, pantothenic acid supports energy metabolism.
In the first 28 days after conception there is formation and closure of neural tube (precursor of the brain and spinal cord) and folate is essential for closure of it. This closure is very important for maintaining brain development. Hence folic acid requirements are significantly increased to 570 µg in pregnancy. Like folic acid, vitamin B12 is required for normal cell division and cell differentiation and for development and myelination (formation of cell membrane of the nerve cells) of the central nervous system. Vitamin B6 facilitates several metabolic processes in nervous system via biosynthesis of neurotransmitters. Vitamin B2 (riboflavin) helps to release energy from macronutrients for the formation and functioning of the skin, lining of the digestive tract, blood cells and other vital organs in the foetus. 80mg of vitamin C is needed for formation of collagen, connective tissues, cartilage, muscles, and the lowest layer of skin. Energy is critically required for cell division and development and later by the foetus as it becomes active. Choline (Betain is a precursor of choline) is a lesser known nutrient but it is critically involved in methylation (donation of methyl group) to homocysteine to form methionine, formation of memory part in hippocampus (brain part), formation of acetylcholine and normal membrane functions.
Since the foetus depends fully on maternal vitamin D supplies. 25(OH)D readily crosses the placenta and it is activated into 1,25(OH)2D by foetal kidneys. Also, vitamin D is important for maintaining maternal calcium homeostasis. However, vitamin D supplementation for pregnant women is not recommended by the World Health Organization.
During pregnancy vitamin A requirements are increased to 900µg/day for growth, cell differentiation, formation of epithelial lining and immune system as well as vision. Vitamin E is an anti-oxidant and hence protects against oxidative stress and protects the intrauterine growth. Vitamin K is needed for formation of prothrombin that has a role in blood coagulation. It is very crucial in neonates. Women on anticoagulant therapy need to be cautious of this vitamin.
Minerals in pregnancy
Iron is critical during pregnancy hence its requirement is increased from 29 to 40 mg /day for synthesis of haemoglobin (important for transporting oxygen to the developing foetus), myoglobin and certain enzymes expansion of blood volume, synthesis of maternal organs, storage of iron in the foetal liver and loss of iron through blood loss at the time of delivery. Iron is also required for neurological development. During the last trimester, the foetus accumulates considerable amount of iron that will be used in the first six months of postnatal life (when the baby is breastfed and milk is a poor source of iron
A pregnant woman needs 250 µg/d iodine to produce foetal thyroid hormones (as the foetal thyroid begins to function only around the twelfth week of gestation); development of normal brain development and maturation of brain cells and for growth, formation and organs and tissues as well as metabolism of glucose, proteins, lipids, calcium and phosphorus, and thermogenesis.
Calcium requirement is 1000mg/day during pregnancy which is same as normal woman because maternal absorption is increased in correspondence to the foetal demand. Calcium is maximally deposited in foetus during the 3rd trimester. Adequate maternal intake not only to supplies adequate calcium to the foetus but also to maintains the maternal bone reserves.
Zinc is also important for structural, metabolic, and immune functions that include cell growth, development, and differentiation. It also supports brain development. Its retention increases with the progress of pregnancy. Zinc is important for nucleic acid metabolism, participates in DNA synthesis (thus is important for protein synthesis) and formation and stabilization of enzymes hence its requirement is also increased during pregnancy @ 14.5mg/d. Plasma copper concentrations progressively increased during pregnancy and return to normal after delivery. This increase relates to the synthesis of ceruloplasmin, due to altered levels of oestrogen.
Effect of Nutritional deficiencies
Single nutrient deficiency is uncommon and multiple nutrient deficits during pregnancy results in of intrauterine growth retardation (IUGR). It alters the rate of growth and development of the fetal organs and tissues. Nutrients are diverted to some important organs such as the brain at the expense of other organs (liver, pancreas, and muscles). These organs are compelled to adapt. There are many scientific evidences that indicate that nutrient deficiencies may contribute to the development and progression of several metabolic disorders in adulthood or manifestation of non- communicable diseases such as rheumatoid arthritis, metabolic disorders (obesity, type 2 diabetes), cardiovascular disease, and cancer are of “foetal origin”. Hence, we can say that the “impact of foetal under nutrition persists throughout life”.
Nutritional challenges exerted by maternal nutrient intake during foetal development influence foetal growth, birth weight, and foetal survival and more importantly have long term implications in terms of functional, metabolic capacity and the risk of chronic, non-communicable diseases in later life of the off spring. Generally, the foetus adapts to the nutritional imbalance by metabolic structural and functional changes. Any nutritional imbalance brings profound changes in maternal and foetal metabolism and physiology.
Protein energy malnutrition is common among pregnant women for various reasons that result in low maternal blood volume, reduced growth of placenta and the foetus, oedema and growth retardation. Deficiency of essential fatty acid like omega -3/DHA impair the brain development particularly the visual acuity.
Deficiency of folic acid is linked to higher risk of several adverse outcomes of pregnancy such as spontaneous abortion, low birth weight, pregnancy-induced hypertension, neural tube defects, and preterm delivery. Children born to B12– deficient mothers may show developmental abnormalities and anaemia. Vitamin A deficit not only leads to foetal growth retardation but also in low birth weight. Deficiency of choline may raise the risk of preeclampsia, premature birth even maternal and neonatal deaths.
Maternal anaemia during pregnancy is associated with neurological defects, low birth weight, perinatal, maternal, and infant mortality as well as higher risk of premature delivery. Hence iron supplements are generally recommended to improve the pregnancy outcome.
Iodine deficiency increases the risk of spontaneous abortion, perinatal mortality, birth defects and neurological disorders. Maternal deficiency of iodine during pregnancy results in foetal hypothyroidism that can cause mental retardation (cretinism). Deficiency in later stages of pregnancy has less severe impact than in the early part of pregnancy. WHO has stated that iodine deficiency is a preventable cause of brain damage? UNICEF recommends that antenatal supplements including zinc, iron, and folic acid to be given to pregnant women in developing countries because they are likely to have low dietary intakes of these micronutrients.
Dietary Guidelines for Pregnant Mothers
- Eat well – balanced meals with plenty of fresh fruits and vegetables
- Increase intake of folate and iron rich foods along with vitamin C rich foods
- Include foods rich in omega-3 fatty acids, calcium, and vitamin A rich foods
- Increase intake of complex carbohydrate foods
- Eat whole fruits instead of fruit juices
- Ensure that the RDA for protein is met by good quality protein sources such as egg, milk, oily fish, and pulses
- Avoid alcohol, caffeine, smoking, tannin rich foods like tea, coffee, cola beverages, high fructose corn syrup, sugar -sweetened beverages
- Avoid ultra-processed and packaged foods
- Reduce intake of salt, sugar, and refined foods (refined flour, refined sugar, and refined oil)
- Regularly drink 8-10 glasses of water or fluids like buttermilk (without salt) or milk
- Avoid skipping meals
- Eat small size meals at a time and eat several times a day, preferably at regular timings
- and consume freshly prepared meals
- Pregnant women should do regular exercise like walking. Before undertaking heavy exercises in a gymnasium, the mother should consult her obstetrician.