Nutritional Needs During Pregnancy

When a woman is pregnant, she is growing not only a baby, but also a placenta. This placenta, like the baby, needs to be adequately nourished to ensure proper implantation and development for efficient functioning. The placenta carries out many essential life functions for the baby. Along with umbilical cord, amniotic sac, and uterus, the placenta is a life support system for this tiny person.

The placenta, in providing nourishment for the baby, works very much like a fuel pump. If the fuel is of poor quality or the wrong octane for the particular engine, the pump will work ineffectively or may even stop completely. Also, if the pressure or the volume of the fuel coming through the pump affected, the pump’s efficiency will be altered. If you think of the nutrients in the bloodstream as fuel, you can see that a poor diet results in a poor quality of nutrients moving through the “placenta-pump”. If the volume of fluid in the bloodstream is inadequate, then the pressure of the blood coming through the “placenta-pump” will be low and the nutrients will not be able to get through in sufficient quantity to adequately nourish the fetus.

The body’s blood volume needs to increase by more than 50 percent during the last half of pregnancy to enable the placenta to be an efficient pump. This increase requires an adequate intake of sodium (salt), along with a sufficient intake of fluids. Many women experience an increased desire for salt during pregnancy. This is the body’s way of ensuring the supply that is needed to help increase its blood volume. Thus, restricting salt may hinder the body’s performance of this vital function and can result in intrauterine growth retardation.

Sufficient fluid intake is also needed for the production of amniotic fluid. By the last weeks of pregnancy, the amniotic sac contains about 1 quart amniotic fluid to cushion and protect the baby. This fluid is replaced every 3 hour. In addition, tissue fluid increases by an estimated 2 to 3 quarts during pregnancy. You need to drink at least 2 quarts of liquid a day to maintain these levels and to ensure a healthy pregnancy. The best fluids to drink are water, milk, and fruit juices. Stay away from alcohol and drinks that contain caffeine.

Many women and doctors are overly concerned about edema (swelling) during pregnancy. Some degree of swelling is normal. The enlarging uterus pressing on the veins of the legs causes dependent edema in women who stand or sit for long periods. In addition, estrogen, which is manufactured by the placenta during pregnancy, causes the tissues to retain extra fluid. Before you were pregnant, you may have noticed water retention just before your menstrual period. Women who took birth control pills may also have experienced it. This was caused by the increased estrogen in the body.

In years past, doctors often treated this normal swelling with diuretics (water pills), as well as with a diet restricted in salt. Fortunately, they no longer follow these practices because of the potential side effects. In addition, almost all obstetrical authors now warn that diuretics can actually increase the symptoms and may even cause more serious side effects, including a rise it the blood pH (the relative acidity or alkalinity of substances), reduced placental exchange of nutrients and waste products, decreased tolerance of carbohydrates, generalized edema, severe loss of calcium through the urine, and sodium depletion. If the swelling is a result of hypovolemia (low blood volume), diuretics may drive salt and water from the circulation and lower the blood volume even further. This could actually cause or accentuate the PIH that the diuretic was supposed to prevent. Sometimes, however, diuretics are indicated in pregnancy, such as when the woman has abnormal swelling due heart disease or kidney disease.

Rather than resort to diuretics or salt restriction, the normal pregnant woman should make certain that her protein consumption is ample (75 to 100 grams) and that her salt intake is adequate. Salt is contained naturally in many foods. During pregnancy, “salt to taste” is a good rule to follow.

Your liver also helps to maintain an increased blood volume during pregnancy. It does this by providing albumin, a protein that keeps water in circulation. An inadequate intake of protein prevents the liver from producing enough albumin to hold water in the bloodstream. The water therefore leaks out into the woman’s tissues, creating abnormal puffiness.

The liver also filters the pregnancy-induced hormones, manufactured by the body in amounts equal to what is supplied by 100 birth control pills taken daily, and rids the body of toxins normally produced in the lower bowel. Altogether, the liver performs approximately 500 functions. Since the liver is under increasing stress as the baby grows, you need to increase your intake of calories, protein, vitamins, and sodium during the last half of your pregnancy to counteract this stress.

The baby’s brain grows the most during the last 2 months, and an adequate intake of protein is essential at this time for building brain cells. So even if your diet has been unstructured up to your seventh month, a change now can still greatly benefit your baby. Conversely, if your diet has been adequate up to your seventh month, but you now begin restricting calories in an effort to control your weight gain, your baby may suffer.

Weight gain is often the focus of too much concern during pregnancy. Gaining weight is expected and necessary for the well-being of the mother-to-be and baby. The amount of weight gain varies from woman to woman, as does the pattern of weight gain. Total weight gain is determined by prepregnant weight, eating habits, daily activities, and metabolism. Since every woman is unique, there is no specific weight gain that is correct for all pregnant women. However, if a woman was underweight before becoming pregnant, she will need to gain more weight than what is expected in the average woman.

Even for overweight women, dieting during pregnancy is risky for both mother-to-be and child. Changing the woman’s diet to eliminate high-calorie junk foods and to include only nutritionally beneficial foods will provide the baby with adequate nourishment. A diet that provides less than 2,300 calories will not provide the nutrients necessary for the baby to grow or for the woman to gain an adequate amount of weight.

Hints For The Mother-to-Be
  • Do not restrict your salt intake unless your doctor can give you documented proof that it is necessary in your particular case.
  • Do not take a diuretic for normal swelling.
  • Do not restrict your calories to "hold down" your weight gain.
  • Do not go for even 24 hours without good food.

During the last weeks of pregnancy, the baby lays down stores of vital minerals and insulating body fat essential for his survival. He builds his stores of iron because his diet for the first 6 months of extrauterine life will be low in it. Even the iron supplement in infant formula is poorly absorbed by babies. Therefore, during the last months of pregnancy, you must eat foods that will provide you and your baby with a sufficient supply of iron. After birth, breast feeding will help. Breastmilk contains just a small amount of iron, but this iron is efficiently absorbed and utilized by the baby, which allows the infant’s iron supply to last longer.

If you are experiencing a multiple pregnancy, your increased nutrition needs are greater than those of a woman carrying a single baby. Each day, need to consume an additional 20 to 25 grams of protein per baby and take at least 300 more calories per baby. Physiologic swelling is even more exaggerated, as you may have additional placentas or one larger placenta producing a greater quantity of estrogen. The larger and heavier uterus restricts the blood flow from the veins of your legs more than normal, increasing dependent edema. The weight gain in a woman carrying twins can be as much as 40 to 50 pounds if she is eating correctly. Women who eat a healthy diet and not restrict their salt intake often give birth to babies who are of normal weight (not less than 5 1/2 pounds) and who arrive at term, not prematurely, as is usually expected.

Gail Sforza Brewer presented the No-Risk Pregnancy Diet in her book The Pregnancy After 30 Workbook. The diet includes daily and weekly food patterns designed to supply the woman and baby with adequate building materials and reserves. The plan is still recognized as an excellent guide for providing maximum nutrition during pregnancy. For a description of the diet plan, see “The No-Risk Pregnancy Diet“.

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