periods of activities. These two aspects may account for 90 percent or more of the total energy expenditure.

TABLE 4-1 Cumulative Energy Cost of Pregnancy Computed from the Energy Equivalents of Protein and Fat Increments and the Energy Cost of Maintaining the Fetus and Added Maternal Tissues

 

Equivalent (kcal/day)a at the Following Weeks of Pregnancy

Cumulative Total

 

0–10

10–20

20–30

30–40

(kcal)

Protein

3.6

10.3

26.7

34.2

5,186

Fat

55.6

235.6

207.6

31.3

36,329

Oxygen consumption

44.8

99.0

148.2

227.2

35,717

Total net energy

104

344.9

382.5

292.7

77,234

Metabolizableb

114

379

421

322

84,957

a Taken as 5.6 kcal/g for protein and 9.5 kcal/g for fat.

b Metabolizable energy = total net energy + 10%.

NOTE. For the first 10-week; period, the total increment is divided by 56 because pregnancy is dated from the last menstrual period.

SOURCE: From Hytten, 1980 (with permission).

Measurements of energy expenditure for metabolism (i.e., basal (BMR) or resting (RMR) metabolic rate) from several groups of pregnant women are given in Table 4-2 (Blackburn and Calloway, 1976; Durnin et al., 1985; Forsum et al., 1985; Lawrence et al., 1984, Nagy and King, 1983). For comparison, the estimated RMR during pregnancy and its total energy cost (Hytten, 1980a) are also presented. The additional amount of energy used for RMR should be comparable with the estimated need for metabolism, that is, 36,000 kcal/pregnancy (Hytten, 1980a). Resting energy metabolism increased in all the groups of women studied, but the incremental increase varied greatly among the groups. The biggest net change in resting metabolism was seen in Swedish women (46,500 kcal), whereas the unsupplemented women in The Gambia (see Chapter 3) had the lowest change (1,000 kcal).

Studies from The Gambia suggest that maternal nutritional status influences the level of change in resting metabolism during gestation. The unsupplemented women, who consumed only 1,500 kcal/day, had lower RMRs in the second and third trimesters than did the women who received supplements and consumed about 1,950 kcal/day (Lawrence et al., 1984; Prentice et al., 1983). The supplemented women required an additional 13,000 kcal for resting metabolism; only 1,000 kcal were required by the unsupplemented women (Table 4-1).



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