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35 The major identifiable components of the weight gained by term are in Table III. TABLE III IDENTIFIABLE COMPONENTS OF WEIGHT GAINED AT 40 WEEKS GESTATION Tissues or Fluid Fetus Placenta Amniotic fluid Uterus Breasts Blood Interstitial fluid TOTAL Tot tal weight gained during pregnancy Weight gain not accounted for Weight (grams) Weight (pounds ) Reference 3,500 7.7 10 650 1.4 15 800 1.8 15 900 2.0 15 405 0.9 15 1,800 4.0 27 1,200 2.7 20.5 15 9,255 10,896 24.0 1,641 3.5 In these averaged figures, shown in Table III, about 3.5 pounds of the total are unaccounted for. This discrepancy can be taken as a measure of maternal storage of nutrients, principally fat. (15) Planning a weight control program aimed at limiting gain to less than 24 pounds assumes knowledge of a woman's body stores and dietary intake which is generally not available, The danger exists of interfering with the normal physiological processes of both the mother and the fetus. Thus, a rational program for a healthy pregnant woman should provide a diet
36 which contains all of the required nutrients v/ith sufficient calories to support a steady gain in weight of 0.5 to 0.8 pounds per week to a total of approximately 24 pounds. A gain of less than this amount is likely to be at the expense of either the mother or the fetus or both. It is important, however, to emphasize that normal gain in weight and rate of gain by themselves give no assurance that the patient's nutrition is necessarily optimal. For such assurance, the dietary intake of the patient must frequently be assessed and evaluated in the context of her "total status1.'. i Furthermore, every effort must be made to distinguish between the normal steady gain in weight of 0.5 to 0.8 pounds per week and that due to edema, usually evidenced by the sudden gains characteristic of water retention. The Underweight Pregnant Woman: Although it was pointed out by Tompkins, et. al. (31) that patients who were 15 per cent or more underweight at the onset of pregnancy had an increased incidence of severe toxemia and an increased num- ber of low birth weight infants, this subject has received relatively little attention in recent years. (29) Burke (5) noted that underweight women made the largest average gains in weight during pregnancy; they retained the most weight post partum; and they had the smallest babies. It
37 . would seem justifiable, therefore, to design a weight control program for underweight women to include sufficient nutrients, particularly protein, to provide for the needs of the fetus and to support the gain in weight characteristic of a normal preg- nancy. (Figure 1, Appendix page 55) The Overweight Pregnant Woman: Obese women tend to have more complications during pregnancy (toxemia, diabetes), labor (uterine inertia), and delivery (dystocia, cesarean section), and give birth to large babies. On the other hand, they tend to have a low incidence of low birth weight infants. (17) In the management of the obese pregnant woman, it is necessary to bear in mind that the existing body-weight usually represents a weight accumulation of many years and does not necessarily reflect her current caloric intake. During pregnancy the optimum management is an adjustment of food intake, if required, to improve the quality of the diet. Whether an obese woman should attempt to lose weight during pregnancy depends on her individual circumstances. Under close supervision, weight reduction programs have been successful, but the question remains whether weight reduction during pregnancy is either necessary or desirable. The emphasis in nutritional management of obese women, as in all women, must be placed on provision of the
38 recommended daily allowances of all nutrients. Weight reduc- tion per se should be handled as a separate problem post partum. The most important aspect of a weight control program for obese pregnant women may well be that of developing attitudes, know- ledge, self-understanding, and improved dietary habits that will make her post partum weight control program more satis- fying and effective. Maternal Nutrition and Toxemia of Pregnancy Perhaps no aspect of maternal nutrition has excited so much interest or aroused so much controversy as the role of nutrition in the etiology and management of toxemia (pre- eclampsia and eclampsia) of pregnancy. The recent report of a WHO Expert Committee on Nutrition in Pregnancy and Lactation, 1965 (28) commented: The incidence of pre-eclampsia and eclampsia is so intimately affected by standards of antenatal care that it is difficult on the evidence available to define the precise role of nutrition in toxemia, except to state the nutritional status of the patient may possibly modify the course of the disease. On the other hand, many authorities believe that nutritional factors are of prime importance, although the mechanisms through which poor nutrition operates in the development of pregnancy toxemia remain obscure. It is commonly accepted that when two of three "cardinal" findings are present simultaneously in a patient, the existence
39 of the toxemia syndrome is established. The three are: 1) a persistent rise in diastolic blood pressure to 90 mm Hg or higher after the 24th week of pregnancy, 2) the presence of non- dependent edema, and 3) two or more episodes of proteinuria not attributable to infection. Reid (27) pointed out that the earliest sign of mild toxemia may be found several weeks prior to the later phase when the cardinal signs appear. This earliest phase is characterized by sudden gain in weight which is unexplainable on the basis of caloric intake alone. It should be emphasized that although sudden gain in weight is not necessarily considered to be a precursor of toxemia or pre-eclampsia, nevertheless, in practice, patients with sudden or rapid gain in weight are often treated vigorously on this assumption. The importance of toxemia can be illustrated by several observations. Toxemia of pregnancy is a leading cause of maternal deaths in this country, (22) accounting for about one-sixth of all maternal deaths, and is undoubtedly responsible for large number of stillbirths and neonatal deaths each year in the United States. The harmful effects of pregnancy toxemia on the fetus and on the later development of the child appear to be closely related to the deleterious effects of the disease on the fetus in utero. That is, toxemia appears to be a causative factor in producing low birth-weight, but gestationally mature infants (dysmature or small-for-date
40 infants) perhaps by altering the fetal-placental exchange which results in inadequate nutrition of the fetus and fetal growth retardation. (12) (23) Toxemia also contributes to the numbers of low birth-weight infants because it necessitates therapeutic early termination of pregnancy. The incidence of established toxemia has been reported to be 1.5 per cent in private patients and 10 to 12 per cent in patients served by teaching hospitals. (27) These incidence figures, however, may give unreliable estimates of the magnitude of the problem. Clinic patients have a higher incidence of all complications and figures based on such groups are not representative of all pregnant women. In the Kauai Pregnancy Study, which included all pregnant women in a community, the overall incidence of toxemia was 6.6 per cent. (2) Many clinics have established policies which in effect result in routine treatment of all patients as though they potentially might develop toxemia. In these clinics routine management often includes salt restriction, activity restric- tion, and the liberal use of diuretics, particularly for patients who show any suggestive increase in rate of gain in weight. Such management makes it difficult to even approximate the true incidence of toxemia. Present evidence does not support the routine restriction of sodium in management of normal pregnancy.
41 1 Prevention of Pregnancy Toxemia:. Most obstetricians believe that eclampsia can be almost totally prevented and that the incidence of pre-eclampsia can be materially reduced. Tompkins and associates (31), under carefully controlled circumstances, found that in clinic patients receiving adequate protein and vitamin supplementation the incidence of diagnosable toxemia could be reduced to 0.6 per cent in contrast to an incidence of 4.7 per cent in a non-supplemented control group. All of these patients were seen at regular intervals, by the same obstetricians in the research clinic. Because of the many variables in the management of toxemic patients, including support and activity restrictions, it is-nearly impossible to disentangle the precise role of a nutrient or of nutrition from other important therapeutic measures employed. Nevertheless, nutritional manipulation did differentiate the groups in Tompkin's studies, indicating that the incidence of toxemia in a population may be sharply reduced by these means. The studies of others, Ebbs, Tisdall, and Scott, 1941, 1942, (8) Burke and Kirkwood, 1950,(6) Hamlin, 1952, (13) and Corkill, 1961, (7) lend support to Tompkin's observations. Corkill (7) in commenting on the reasons for the striking improvements in toxemia control in Australia and New
42 Zealand cited in particular the closer attention given to early signs of edema as an important advance. In commenting on the role of nutrition, he statest In fact, instead of searching for the cause of toxemia in nutrient deficiencies or excesses we were beginning to understand the nutritional needs of pregnancy more clearly and were coming to appreciate the fact that the true place of dietary factors in relation to the toxemias was in the maintenance of physiological efficiency. Nutritional Components in the Treatment of Established Toxemia: The treatment of established toxemia will vary depending on the degree of proteinuria and hypertension and the presence or absence of other symptoms. If the disease is severe or the fetus is believed to be mature enough to be delivered safely, the best treatment may be termination of the pregnancy. Tf the disease is relatively mild and the duration of pregnancy is less than 35 weeks, the patient can be treated, with the hope that the pregnancy may be carried to near term. It is in this latter situation that nutrition service is important. The basic dietary principles employed in pre- vention apply here and consist of a nutritionally adequate diet including a high level of protein (100 g), avoidance of excessive salt, and sufficient calories to meet energy require- ments. It should be emphasized that toxemic women may require more food than they have been eating. However, they are often
43 treated -with sharp restrictions in their caloric intakes as though excess caloric intake is the only cause of the excessive gain in weight. In fact, a careful dietary history and appraisal of nutritional status are likely to disclose a generalized state of poor nutrition. Further study is neces- sary to determine if there is a need for salt restriction once the desired intake of nutrients has been achieved. Muscle Cramps Muscle cramps, caused by sustained involuntary and painful muscle contractions, while not peculiar to pregnancy, are a common complaint during pregnancy. Usually a single muscle group is involved and the calf muscles are mainly affected during pregnancy. These spasms commonly occur at night although they may follow unusual muscular activity. Muscle cramps have been attributed to sodium depletion, peripheral vascular insufficiency, or lowered serum calcium levels, (18) but available evidence is insufficient to permit any firm conclusion about either etiology or treatment. (11) There is no evidence that a. restricted miJLk intake favorably affects the incidence of leg cramps. Calcium lactate (18) and thiamine sources (16, 32) have been administered to relieve this condition. Vitamin and Mineral Supplementation The ideal source of vitamins and minerals is the foods
44 that make up a diet adequate in essential nutrients. These needed foods are available in nearly all market-places. Amounts of nutrients greater than the NRG Recommended Dietary Allowances provide no further protective benefits in pregnancy, as shown by the Vanderbilt study. (20) However, some expectant mothers, especially those who entered pregnancy in poor nutritive status, or are still growing, or are unable to obtain or toler- ate all foods recommended may require additional nutrients beyond those normally furnished by the diet. In such cases, the physician may find it necessary to prescribe supplementary or therapeutic amounts"~df minerals and/or vitamins. The relation of newborn rickets to maternal deficiency of calcium and vitamin D is well known. In the United States rickets is virtually unknown today largely because of vitamin D supplementation of milk. Vitamin D in excess has been implicated recently in causing congenital malformations and mental retardation. (see Chapter II, page 23) The syndrome of hemorrhagic disease of the newborn is not clearly defined clinical entity, but the prolonged prothrombin time demonstrable in such newborns has been ascribed to a vitamin K deficiency. It is common medical practice to administer a vitamin K prepara- tion to the woman in labor or to the neonate. There is no established evidence that diets of pregnant women require "routine" vitamin supplementation, particularly
45 if the woman is eating a well balanced diet. It is, however, customary practice to prescribe vitamin supplements for those women whose diets are or have been substandard, and for those women with chronic gastrointestinal disorders for whom absorp- tion of vitamins may be impaired. When prescribing vitamin and mineral supplements it is essential to guard against the possibility that some women because of their expenditures for supplements, raay be forced to deprive themselves of the other essential nutrients found only in foods. Anemia in Pregnancy Iron deficiency anemia is considered to be the most common complication of pregnancy in American women. Folic acid deficiency, chronic infection, and hemoglobinopathies are only rarely responsible. The prevalence of anemia in pregnancy in the United States varies widely in different groups of women and according to the criteria utilized for diagnosis. Rates of from 15 to 58 per cent are reported (1, 14, 19, 25). The menstruating woman has a larger requirement for iron than the adult male or post-menopausal female. Although menstrual losses discontinue during pregnancy, additional iron is required to meet the increasing needs of fetus and placenta and for replacement of blood loss during delivery. The net iron loss
46 during a pregnancy is approximately 300-400 mg. In normal pregnancy there is a decreased concentration of blood hemoglobin and of serum iron and an increase in unbound iron binding capacity. The total circulating hemoglobin and serum iron may be little changed, however, because of the physiologic increase in total blood volume which accompanies pregnancy. Relatively little information is available concerning the changes which occur in iron stores in bone marrow. Consideration of all of these factors makes it exceed- ingly difficult to assess the true incidence of iron deficiency anemia in pregnancy. Nevertheless, it cannot be denied that large demands are made on the iron stores of a pregnant woman, emu if Lntjyt; t> Lores are low as a woman enters pregnancy, iron deficiency is likely to result. Provision of supplemental iron has been found to increase blood hemoglobin and serum iron levels of normal pregnant women. The recommended dietary allowance for iron in pregnancy is 20 mg daily. This quantity may not be readily consumed in a daily diet with usual American food patterns. Careful planning of iron intake is therefore needed. Moreover, the allowance itself may provide but a small margin of safety, particularly for the pregnant adolescent who may still be grow- ing or for a woman with previously reduced iron stores resulting
47 from menorrhagia or repeated pregnancies. Therefore, provision of supplemental iron should be considered for all pregnant women. An iron supplement affording 100 to 150 mgs daily of elemental iron may be recommended, with the iron provided in the ferrous form and in divided doses three to four times a day. Hyperemesis Nausea and to a lesser extent vomiting occur frequently in association with pregnancy. Probably 50 per cent of all pregnant women experience some degree of nausea and minimal vomiting. The cause is unknown, but physiological and psycholo- gical factors are thought to play a part. Hyperemesis gravidarum or pernicious vomiting is uncommon, occuring in 1 in 300 pregnancies and is usually confined to the first trimester. Pernicious vomiting occurs infrequently among patients in lower socio-economic groups. For most patients the nausea and vomiting usually does not interfere with their nutritional status. Mild sedation or phenothiazine usually keep symptoms at a minimum. Specific treatment with vitamin preparations (vitamin B complex and ascorbic acid, separate or in combination) has been advocated. These medications along with hormones, Lugol's solution, and other drugs, are probably effective by virtue of their psycholo- gical impact.
48 Dietary adjustments commonly used to relieve nausea include feeding small amounts of "dry foods every two hours" or an alternate "dry and liquid" feeding pattern. (4) If these dietary adjustments are not effective in relieving the nausea, the patient may discover by trial and error those foods which are tolerated and those which are not. Simple measures such as these along with continued reassurance by the physician will usually control the nausea of early pregnancy. As a word of caution, it is not uncommon for women experiencing the nausea of early pregnancy to lose weight. Weight recorded during this period of fluctuation is apt to be misleading and may result in the design of a weight control program which seriously underestimates the total desirable gain in weight during.pregnancy. Therefore, when designing a weight control program, the patient's prepregnant and/or desirable weight should be used, rather than weight recorded during the period of nausea. Pernicious vomiting on the other hand may produce starvation and may require hospitalization. Disturbances of body fluids and electrolytes may result and large losses in weight take place. Correction of dehydration and electrolyte imbalance by intravenous feedings, sedation, and emotional reinforcement help to relieve symptoms and restore normal
49 eating habits. It is customary to add vitamin B complex and vitamin C to the intravenous solutions. Because the syndrome is usually limited, the over-all effect on nutrition in pregnancy may be minimal.