When food is scarce, however, fetal 
growth is retarded. For example, in 
1945 during the famine imposed by 
the Nazis in Holland, birth weight 
dropped significantly. Today in sev- 
eral rural Guatemalan villages aver- 
age birth weights are noticeably low 
and studies have shown that they can 
be made to rise significantly by in- 
creasing the amount of food available 
to pregnant women. 
Data such as these have led to a 
reevaluation of feeding practices dur- 
ing pregnancy and a series of rec- 
ommendations that are quite different 
from those of only ten years ago. Doc- 
tors now advise that a woman consume 
enough calories to gain at least twenty- 
five pounds during the course of preg- 
nancy. This can be determined by 
studying pregnant women who are nei- 
ther urged to eat nor discouraged from 
eating and totaling the average weight 
gained as a result of the various ma- 
ternal adaptations to pregnancy and 
the average weight of the fetal com- 
ponents and the placenta. More pre- 
cisely, the uterus and breast tissue 
increase about one and a half pounds 
each; the increased maternal blood 
volume accounts for more than one 
pound; and the mother deposits ten 
to twelve pounds of fat. Thus the ma- 
ternal adaptation accounts for about 
fourteen to sixteen pounds. The fetus 
weighs seven to eight pounds; the pla- 
centa, one to two pounds; and the 
amniotic fluid, which bathes the fetus, 
about one pound. The fetal compart- 
ment therefore represents nine to elev- 
en pounds, making a total weight gain 
of twenty-five pounds. 
Left to their own devices, most 
women do gain about twenty-five 
pounds during pregnancy, and statis- 
tics show that a normally nourished 
woman with a weight gain of twenty- 
five pounds can expect to produce an 
infant of about eight pounds. It should 
be noted that women who are under- 
weight prior to pregnancy need to gain 
more than twenty-five pounds to pro- 
duce an infant of comparable size, 
whereas women who are overweight 
prior to pregnancy, although able to 
gain somewhat less weight, must still 
gain a minimum of about fifteen 
pounds. The crucial element involved 
in this weight gain is calories. If the 
number of calories consumed daily is 
increased by 300 to 500, a twenty- 
five pound weight gain will result. 
Why are we so concerned with ade- 
quate fetal size? Statistically, an in- 
fant has a better chance to survive 
and develop normally after birth if 
its birth weight is not low. Some sta- 
tistics in the United States illustrate 
this point dramatically. The United 
States has only the eighteenth lowest 
rate of infant mortality in the world. 
In other words, an infant born in sev- 
enteen other countries (including Ja- 
pan, Australia, and the German Dem- 
ocratic Republic) has a better chance 
to survive than one born in the United 
States — not a record to be proud of. 
Most of the high rates of infant 
mortality are found in the poorer seg- 
ments of the U.S. population, particu- 
larly among blacks. In some groups, 
infant mortality may be two to three 
times as high as among middle-class 
populations. But pound for pound, the 
poor baby does as well as the rich 
baby; black babies do as well as white 
babies. The difference in mortality can 
be entirely explained by the fact that 
babies from these disadvantaged 
groups weigh on the average half a 
pound less at birth than middle-class 
babies. Theoretically at least, if we 
could raise the average birth weight in 
this portion of the population by a half 
pound, we could erase the difference 
and significantly reduce our overall in- 
fant mortality. Poor maternal nutrition 
is certainly one of the many factors con- 
tributing to this low birth weight. 
Thus the first and most important 
dietary recommendation for pregnant 
women is to increase their food intake 
so that the number of calories they 
consume daily increases by 300 to 500. 
From the standpoint of fetal growth, 
the source of these calories is not im- 
portant. For example, in the study in 
Guatemala previously mentioned, 
when 20,000 extra calories were sup- 
plied throughout the course of the 
pregnancy, birth weight increased by 
nearly one pound. Whether the source 
of those calories was primarily protein 
or carbohydrate made no difference — 
a surprising finding since protein is 
essential to enable an infant to build 
new tissues. Recent experiments with 
animals may provide an explanation. 
Rats fed a restricted diet have 
smaller pups at birth, and supplemen- 
tation with either protein or carbo- 
hydrate returns pup size to normal. 
The composition of the mother’s body 
changes markedly, however, depend- 
ing on which type of supplement is 
used. If protein is supplied, the com- 
position of the mother’s body remains 
essentially normal for pregnancy. If 
carbohydrate is the sole source of the 
extra calories, however, maternal mus- 
cle tissue breaks down to supply the 
amino acids that would have been sup- 
plied by the dietary protein. In other 
words, a sufficient number of calories 
from any source will allow the mother 
to make the adaptations necessary to 
support the fetus, but unless protein 
is supplied, the fetus will derive amino 
acids from the mother’s body. In this 
situation the fetus does become a para- 
site. For that reason it is indeed im- 
portant for a pregnant woman to in- 
clude a significant amount of protein 
in the foods with which she supple- 
ments her normal diet. 
The present recommendation is that 
a pregnant woman increase her daily 
intake of protein by thirty grams. If 
the mother is on a reasonably balanced 
diet, this can be accomplished by sim- 
ply increasing the amount of food she 
consumes. Certain specific nutrients 
are required in particularly large 
amounts in pregnancy, however, be- 
cause of the special demands of the 
mother, the fetus, or both. These are 
the minerals iron and calcium and cer- 
tain vitamins such as folic acid and 
vitamin B 6 . 
Iron is an integral part of the he- 
moglobin molecule and is therefore 
an essential component of blood. With 
the expansion in the volume of ma- 
ternal blood, more iron is needed by 
the mother. Moreover, the fetus must 
manufacture its own blood supply — a 
supply that increases with fetal 
growth; hence large amounts of iron 
are needed by the fetus as well. Iron 
is normally present in only marginal 
amounts, however, and although iron 
is absorbed much more efficiently dur- 
ing pregnancy, in the past when the 
mother’s intake of food was limited, 
iron intake had to be supplemented 
to prevent deficiency. Even now that 
the mother’s food intake is being in- 
creased, supplementation during preg- 
nancy is advisable unless special care 
is taken to consume iron-rich foods 
(for example, red meats, fortified 
grain products, beans, and dried fruit). 
Calcium is necessary for proper de- 
velopment of the fetal skeleton and 
therefore is required in increased 
amounts during pregnancy. Supple- 
mentation is not usually necessary, 
however, since the mother’s absorption 
of calcium from foods is markedly 
increased. (But because dairy prod- 
ucts are an important source of cal- 
cium, a woman following a strict vege- 
tarian regime during pregnancy may 
wish to take both calcium and iron 
supplements.) On the other hand, cal- 
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