recommended for each food group can be compared to that recorded by a pregnant woman and the results used to iden-tify the general quality of the diet. Table 4.32 shows how closely the example of a day’s diet based on MyPyramid recommendations matches recommended levels of nutri-ent intake for pregnancy. With the exception of vitamin E and iron (which are supplied in rather low amounts by the example diet), nutrient levels correspond to recommended intakes for pregnancy.
Computerized analysis, given accurate records and entry of dietary intake and a high-quality nutrient data-base, provides results useful for estimating the quantity of calories and nutrients consumed. Detailed knowledge of dietary intake is particularly useful for women at risk of nutrient inadequacies or excesses, and for women with conditions such as gestational diabetes, food intolerances, and multifetal pregnancy.
Nutrition Biomarker Assessment
Nutrition assessment of pregnant women usually includes laboratory tests of iron status, and will include tests to de-termine the status of other nutrients as indicated. Due to the normal physiological changes occurring during preg-nancy, such as hemodilution, that affect blood nutrient concentrations, assessment of nutrition biomarkers should
employ standards developed for pregnancy.202 Blood nu-trient concentrations change with time during pregnancy, so no one value per nutrient for all of pregnancy accu-rately reflects status.
Studies reporting reference values for nutrition biomar-kers during pregnancy are beginning to appear in the scien-tific literature. These values are shown in Table 4.33. The concentrations listed by week of gestation consists of values from the 2.5 percentile to the 97.5 percentile of the distri-bution of values within a sample of well-nourished women with healthy, uncomplicated pregnancies. These values are assumed to reflect normal ranges of nutrition biomarker concentrations during pregnancy. They are intended to assist clinicians in distinguishing between physiological changes and pathological states during pregnancy.202
Dietary Supplements
herbal supplements on their own.203 Clinicians in gen-eral support the use of certain dietary supplements. Of 900 doctors and 277 nurses included in a recent survey, 73 to 89% personally used supplements, and 79 to 82%
recommended that their patients use them.204 There is
little evidence supporting the safety and effectiveness of many of the dietary sup-plements available on the market and used by pregnant women, however.
Multivitamin and Mineral Prenatal Supplements
With the exception of iron, nutrient needs during pregnancy should be met by the consumption of a well-balanced and adequate diet.97 This approach to meet-ing nutrient needs should be considered first because foods provide antioxidants, fiber, and other beneficial bioactive substances. Healthy diets also provide adequate amounts of protein, health-promoting sources of dietary fat, and nutrient-rich sources of carbohydrates.97
Multivitamin and mineral prenatal supplements may benefit women who:
● Do not ordinarily consume an adequate diet
● Have multifetal pregnancy
● Smoke, drink, or use drugs
● Are vegans
● Have iron deficiency anemia
● Have a diagnosed nutrient deficiency34, 206, 205
Standard prenatal multivitamin and min-eral supplements taken before and during pregnancy appear to benefit women in need of them. Prenatal vitamin and min-eral supplement use by low-income preg-nant women has been found to decrease the risk of preterm, low birth weight, and certain congenital malformations.208,209
About 95% of all pregnant women and 75% of women in WIC take a vita-min and vita-mineral supplement regularly during pregnancy.45,210 Hundreds of types of prenatal supplements are available by prescription (those that contain over 1 mg folic acid), over the counter, or on the In-ternet. They contain an amazing array of nutrients, from vitamins and minerals to seaweed, borage, and don guai. Some of the prenatal supplements sold over the In-ternet contain ingredients that are not considered safe for use in pregnancy, and others provide unreasonably high levels of vitamins or minerals. Table 4.34 summarizes the range in nutrient amounts found in 12 examples of prenatal supplements and compares the amounts to mean nutrient Table 4.33 Reference values for nutrition biomarkers during normal
pregnancy in healthy womena, 158,178,179,202
Nutrient Weeks Gestation Reference Values
Calcium, mmol/L 7–17 2.18–2.53
24–28 2.04–2.40
34–38 2.04–2.41
Chloride, mmol/L 7–17 100–107
24–28 99–108
34–38 97–109
Ferritin, mg/L 7–17 7.1–106.4
24–28 3.8–49.8
34–38 4.8–43.5
Hemoglobin, g/dL 0–14 .11.0
14–26 .10.5
26–40 .110.0
Hematocrit, % 0–14 .33.0
14–26 .32.0
26–40 .33.0
Iodin, urinary, mg/L 0–40 150–249
Iron, mmol/L 7–17 8.7–37.0
24–28 8.0–50.0
34–38 7.6–34.5
Magnesium, mmol/L 7–17 0.70–0.96
24–28 0.63–0.91
34–38 0.57–0.87
Potassium, mmol/L 7–17 3.24–4.86
24–28 3.27–4.62
34–38 3.32–5.09
Sodium, mmol/L 7–17 133.2–140.5
24–28 129.2–139.3
34–38 127.0–140.2
Transferrin, g/L 7–17 1.92–3.85
24–28 2.72–4.36
34–38 2.88–5.12
Triglycerides, mmol/L 7–17 0.55–3.08
24–28 1.09–3.63
34–38 1.62–5.12
Vitamin D, nmol/L 0–40 $80 (optimum)
(25-hydroxyvitamin D) ,35 (deficient)
a See Appendix B for a table of factors used to convert SI Units to conventional units. Nutrition biomarkers considered to be in the normal range vary based on percentile cut-points used. The 5th to 95th percentiles are sometimes used and not the 2.5 to 97.5 percentiles reported in this table. Reference values and blood nutrient concentrations considered “normal” or “abnormal”
during pregnancy change based on advances in knowledge. The symbol “mg” means “micro-grams,” sometimes abbreviated as mcg.
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intakes of women in the Untied States, recommended intake levels during pregnancy, and the Tolerable Upper Intake Levels (ULs) of nutrients for pregnancy.
Supplements provided to pregnant women should contain the essential nutrients most likely to be lacking in their diets. These nutrients include vitamin B6, folic acid, vitamin D, iron, iodine, and EPA1DHA.206 Nutrient amounts should approximate recom mended intake levels and not exceed Tolerable Upper Intake Levels for preg-nant women. Supplement use should be accompanied by nutritional counseling that helps women select and con-sume foods that add up to a healthful diet.
Herbal Remedies and Pregnancy
Herbs are generally regarded by the public and by some health professionals as helpful, safe, and gentle. It is esti-mated that in the eastern United States, 45% of pregnant women use herbal products during pregnancy. Women may not report use of herbs to their health care provider based on concerns about the provider’s knowledge about herbs or a bias against them.203
The active ingredients of herbal products are often similar to those in medications that may not be approved for use in pregnancy.58 About one-third of commonly used herbal supplements have been deemed unsafe for use by pregnant women.207 Table 4.35 lists some of these herbs. Women who use herbs should be provided respect-ful counseling about effectiveness and safety, and directed toward reliable sources of information about them.203
Advice to use herbal remedies during pregnancy appears to be based primarily on their traditional use in different societies. This strategy for assessing the safety of herbs doesn’t always work. Some herbs considered safe based on traditional use have been found to produce malformations in animal studies.211 Others, such as blue cohosh, which was previously thought to safely induce uterine contractions, may increase the risk of heart fail-ure in the baby.212 Ginseng, the most commonly used herb in the world, has been found to cause malformations in rat embryos, 211 and ginkgo may promote excessive bleed-ing.213 Peppermint tea and ginger root, taken for nausea, appear to be safe.211
Table 4.34 Range of daily dose levels of nutrients in 12 prenatal supplements and comparison with recommended intake levels during pregnancy and mean intakes of nutrients for women age 20–29 yearsa
Nutrient
Range in
Amounts RDA
Mean Intake,
20–29-Year-Old Women UL
Vitamin A 3000–8000 IU 2564 IU 1572 IU 9990 IU
Vitamin E 4–60 IU 22 IU 9.7 IU 1490 IU
Vitamin B6 2.6–25 mg 1.9 mg 1.6 mg 100 mg
Folate 800–1000 mcg 600 mcg 474 mcg 1000 mcg
Vitamin B12 4–100 mcg 2.6 mcg 4.0 mcg —
Vitamin C 60–120 mg 85 mg 82 mg 2000 mg
Vitamin D 400–610 IU 200 IU — 2000 IU
Calcium 68–1300 mg 1000 mg 806 mg 2500 mg
Magnesium 20–200 mg 350 mg 242 mg 350 mg
Iron 21–51 mg 27 mg 13.8 mg 45 mg
Iodine 0–290 mcg 220 mcg 200 mcg 1100 mcg
Zinc 15–30 mg 11 mg 10.8 mg 40 mg
DHA/DHA1EPA 0–440 mg — 80 mg —
aPrenatal nutrient supplement content determined from company website information, 5/09. United States population-wide information on average nutrient intake of pregnant women is unavailable, so data for women age 20 to 29 are used.114 RDAs listed are for 19–30-year-old pregnant women, and Tolerable Upper Intake Levels (ULs) for pregnant women age 19–50 years. Table developed by Judith E. Brown, 7/09.
Table 4.35 Herbs to avoid in pregnancy211,212
Aloe vera Ergot
Anise Feverfew
Black cohosh Ginkgo
Black haw Ginseng
Blue cohosh Juniper
Borage Kava
Buckthorn Licorice
Comfrey Pennyroyal
Cotton root Raspberry leaf
Dandelion leaf Saw palmetto Ephedra, ma huang Senna
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Ginger, given in oral doses of 1 gram daily for 4 days, has been found to decrease the severity of nausea and vomiting during pregnancy in a majority of women.
Ginger use in this study involving 70 women was not re-lated to complications of pregnancy or poor pregnancy