A Diet for a Healthy Pregnancy - Nutritional Influences on Illness

Townsend Letter for Doctors and Patients,  Jan, 2002  by Melvyn R. Werbach

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All pregnant women should be on a nutritious, well-balanced diet which includes between 70 and 90 gm of protein and between 2,300 and 2,800 kcal per day. Too high a carbohydrate intake in early pregnancy, especially if combined with a low dairy protein intake in late pregnancy, appears to suppress placental growth and results in low birth weight infants. (1)

Dietary Fiber

A high intake of dietary fiber has been correlated with a reduced risk of toxemia in several studies. (2) Also, vegetable fibers with a high viscosity are known to reduce the levels of basal and postprandial glycemia in both normal and diabetic subjects. When 34 pregnant women received either glucomannan or guar supplements, all demonstrated reductions in basal glucose levels as well as levels following an oral glucose tolerance test, suggesting that the supplement may reduce the risk of gestational diabetes. (3)

Dietary Fats

To investigate why women with gestational diabetes mellitus in one pregnancy have a recurrence rate of only 30 to 50% in their subsequent pregnancy, the dietary fat intake for women with a recurrence of gestational diabetes mellitus was compared to that for women with no recurrence of the disease. The women with the recurrence were found to consume a significantly higher percentage of their total energy intake as fats. Given the known relationship between saturated fat intake and insulin resistance, this suggests that the reduction of dietary fats before and during pregnancy may reduce the recurrence rate of gestational diabetes. (4)

Trans Fatty Acids

When plasma trans fatty acid levels of women who delivered pre-term infants were compared to those of women who delivered at term, an inverse correlation was found both with gestational age and birth weight, suggesting that trans isomers of unsaturated fatty acids may impair intrauterine growth. (5) 'Moreover, a study of premature infants at day 4 of life found an inverse correlation between the infants' plasma trans fatty acid levels and birth weight. (6)

Since trans fatty acids inhibit the activity of the enzyme delta-6desaturase, more studies are needed to ascertain whether maternal trans fatty acid intake inhibits essential fatty acid metabolism in the infant and interferes with fetal growth and development. (7) Furthermore, mothers with high intakes of trans fatty acids may have an increased risk of preeclampsia. (8)

Sugar

In a study of almost 500 nondiabetic, pregnant adolescents, the adjusted odds ratio for the delivery of a small-for-gestational age infant of those in the top 10th percentile of total dietary sugar was double that of the remainder of the group, regardless of their ethnicity. (9)

Alcohol

Alcohol is prohibited during pregnancy as it increases the risk of a wide variety of birth abnormalities (10) as well as the risk of spontaneous abortion. (11) The hallmarks of fetal alcohol syndrome are pre- and postnatal growth retardation, central nervous system dysfunction, and characteristic facial dysmorphology.

Caffeine

Caffeine intake should be totally avoided. Numerous studies have found direct correlations between caffeine intake and spontaneous abortion (12) and fetal loss, (13) intrauterine growth retardation, (14) premature membrane rupture, (15) low-birth-weight infants, (12) and sudden infant death syndrome (SIDS). (16) There is even an association between the average annual national coffee consumption and the age-standardized incidence of insulin-dependent diabetes in the zero to 14-year-old age group. (17) Some of these correlations start to be seen with intakes as low as 150 mg day (about one cup of coffee daily) and are notable at 600 mg daily.

Moreover, all of a group of 16 women who ingested more than 500 mg daily of caffeine delivered babies with tremors, and one-quarter of the babies had cardiac rhythm disturbances, suggesting that the infants were suffering from symptoms of caffeine withdrawal. (18)

Milk

Excessive phosphate absorption promotes the development of leg cramps of pregnancy. Milk and dairy products appear to cause a fall in diffusible calcium and a rise in inorganic phosphorus in the blood, probably due to an increased efficiency in the intestinal absorption of phosphates, with a resultant depression of ionized blood calcium. Also, a shift in the acid-base balance to the alkaline side may be contributory. If a pregnant woman with leg cramps is drinking more than 3 pints a day of milk, a reduction of milk intake to less than one pint a day may be adequate to treat the symptom. (19)

References

(1.) Godfrey K et at. Maternal nutrition in early and late pregnancy in relation to placental and fetal growth. BMJ 312:410-5, 1996

(2.) Hipsley EH. Dietary 'fibre' and pregnancy toxaemia. BMJ ii:420-2, 1953

(3.) Cesa F et al. [The use of vegetable fibers in the treatment of pregnancy diabetes and/or excessive weight gain during pregnancy]. Minerva Ginecol 42(6):271-4, 1990

(4.) Moses RG et al. The recurrence of gestational diabetes: could dietary differences in fat intake be an explanation? Diabetes Care 20(11):1647-50, 1997