Week%203 - PowerPoint PPT Presentation

View by Category
About This Presentation
Title:

Week%203

Description:

by learning how to practice evidence-based medicine ourselves. ... Faroe Islands: high birthweights. longer gestations. diet high in marine oils ... – PowerPoint PPT presentation

Number of Views:32
Avg rating:3.0/5.0
Slides: 105
Provided by: donnabj
Category:

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: Week%203


1
10/18/2002
2
  • Carbohydrate
  • Protein
  • Lipids
  • Vitamins and Minerals
  • General
  • Vitamins
  • Iron
  • Zinc
  • Calcium
  • Magnesium

3
What evidence-based medicine is
  • The practice of EBM requires the integration of
  • individual clinical expertise
  • with the
  • best available external clinical evidence from
    systematic research.

4
Three solutions
  • Clinical performance can keep up to date
  • by learning how to practice evidence-based
    medicine ourselves.
  • by seeking and applying evidence-based medical
    summaries generated by others.
  • by accepting evidence-based practice protocols
    developed by our colleagues.

5
The Five Strengths of Evidence
  • Strong Evidence from at least one systematic
    review of multiple well-designed RCT
  • Strong evidence of at least one well designed RCT
    of appropriate size
  • Evidence from well designed trials without
    randomization, single group pre-post, cohort,
    time series or matched case control
  • Evidence from well designed non-experimental
    studies from more than one research group
  • Opinions of respected authorities based on
    clinical evidence, descriptive studies or reports
    of expert committees

6
2002 DRI for Carbohydrate
  • In general all DRIs for carbohydrate based on
    brain glucose utilization.
  • DRI for adults and children 130 g/day
  • Median intake
  • Men 200-330 g/day
  • Women 180-230 g/day

7
2002 DRI for Carbohydrate in Pregnancy
  • Fetal brain needs a minimum of 33 g/day
  • EAR for pregnancy (all ages) 135 g/day
  • RDA for pregnancy (all ages) 175 g/day
  • CV is 15 based on variations in brain glucose
    utilization
  • RDA EAR plus twice CV

CV coefficient of variation (used when
insufficient data to determine standard deviation)
EAR Estimated Average Requirement
8
2002 DRI for Fiber in Pregnancy
  • There is no evidence to suggest the beneficial
    effects of fiber in reducing risk of CHD is
    different from non-pregnant adolescent girls and
    women.
  • AI28 g/day (14 g/1,000 kcal x median kcal intake
    for group)
  • AI for non-pregnant women is 25 g/day

9
Protein - old RDAs
  • 1980 an additional 30 g for pregnancy
  • 1989
  • Protein RDA is 0.8 per kg for non-pregnant woman
  • Additional 10 g for pregnancy

10
Protein - 1989 RDA
11
2002 RDA
12
EAR for Protein in Pregnancy
  • EAR 21 g/day above protein needs at
    prepregnancy weight
  • EAR Per kg
  • Increased amount on a per kg basis is 0.22
    g/protein/kg/day
  • EAR for non-pregnant 0.66 g protein/kg per day
  • EAR per kg0.88 g/kg/day

13
RDA for Protein for Pregnancy
  • 1.1 g/kg/day or 25 g/day additional protein
  • RDA for women aged 19-50 is 0.80 or 46 g/day
  • RDA is 71g protein per day

Reference woman is 57 kg
14
RDA to Diet
  • RDAs calculated using high quality reference
    proteins like egg, meat, milk or fish
  • However, even with adjustments for lower quality
    proteins most women in the US who are meeting
    energy needs with reasonable food choices, will
    meet protein needs.

15
Vegan Diet Protein Intake
16
Protein Intakes
  • Range in US is 75 to 110 g per day for women

17
Energy and Protein
  • If energy needs are not met by diet then protein
    will be used for energy
  • RDA calculations assume adequate energy intake

18
Protein Supplementation
  • In developing countries protein and energy
    supplements may improve pregnancy outcomes when
    women are undernourished
  • There is little evidence that protein
    supplementation affects outcome in developed
    countries

19
Adverse Effects of Protein Supplementation
  • Several human and animal studies of protein
    supplementation have found adverse effects
    including retarded fetal growth, increase in
    prematurity, and increased neonatal deaths..

20
Cochran Collection High protein supplementation
in pregnancy
  • Background and objectives To assess the effects
    of providing pregnant women with high-protein
    nutritional supplements on gestational weight
    gain and on the outcome of pregnancy, including
    fetal growth, gestational duration, and maternal
    and fetal/infant morbidity and mortality.

21
Cochran Collection High protein supplementation
in pregnancy
  • Selection criteria All acceptably controlled
    comparisons of protein/energy supplementation in
    which the protein content of the supplement
    provided gt25 of its total energy content.

22
Cochran Collection High protein supplementation
in pregnancy
  • Main results Two studies involving 1076 women
    were included. High protein supplementation was
    associated with a small, statistically
    nonsignificant increase in weekly maternal weight
    gain. The two available trials provide no
    evidence of benefit on fetal growth indeed, the
    adjusted mean difference in birth weight is -58.4
    g. One trial also reported a nonsignificantly
    increased risk of neonatal death with
    high-protein supplementation.

23
Cochrane Collection Isocaloric balanced protein
supplementation in pregnancy
  • Main results Three trials involving 966 women
    were included. The results suggest a decrease in
    maternal weight gain and mean birth weight and an
    increased risk of small-for-gestational-age (SGA)
    births with isocaloric protein supplementation,
    but no effect on mean gestational age or preterm
    birth. The data are insufficient to exclude
    potentially important effects on fetal or
    neonatal mortality, and maternal health outcomes
    have not been reported.

24
Cochrane Collection Isocaloric balanced protein
supplementation in pregnancy
  • Reviewers' conclusions Balanced protein
    supplementation alone (ie without energy
    supplementation) is unlikely to be of benefit to
    pregnant women or their infants.

25
Cochran Collection Balanced protein/energy
supplementation in pregnancy
  • Background and objectives To assess the effects
    of providing pregnant women with a 'balanced'
    protein/energy supplement (ie, a supplement in
    which the protein accounts for lt25 of the total
    energy content) on gestational weight gain, the
    outcome of pregnancy, and postnatal infant
    outcomes.
  • Studies were all in high risk women - mostly in
    developing countries

26
Cochran Collection Balanced protein/energy
supplementation in pregnancy
  • Main results Fourteen studies were included.
    Balanced protein/energy supplementation results
    in modest increases in maternal weight gain and
    fetal growth. These increases do not appear
    larger in under-nourished women, although larger
    effects were reported in a recent trial in
    under-nourished women from the Gambia that
    provided much higher energy supplements.
    Beneficial effects on fetal and neonatal
    mortality have also been demonstrated. The
    available evidence is inadequate to reach
    conclusions concerning effects on preterm birth
    or maternal health.

27
Cochran Collection Balanced protein/energy
supplementation in pregnancy
  • Reviewers' conclusions Balanced energy/protein
    supplementation appears to reduce the risk of
    both fetal death (stillbirth) and neonatal death.
    Such supplementation also improves fetal growth,
    but the improvement appears modest unless the
    supplement provides a very large net increase in
    energy intake. The effect on fetal growth does
    not appear to be associated with long-term
    benefit to the offspring, and no benefit has been
    demonstrated on maternal health.

28
Lipids
  • General
  • maternal
  • fetal
  • LCPUFA
  • Trans FA

29
Lipids Maternal
  • Metabolism changes to
  • meet increased maternal needs for energy and
    hormones precursors
  • to insure adequate fetal accretion
  • Serum cholesterol rises 25-40
  • Triglycerides rise 200-400

30
Lipids Maternal Recommendations
  • 30 of kcals from fat is a reasonable goal in
    pregnancy.
  • There is no need to try to affect the
    physiological rise in blood lipids

31
Essential Fatty Acids in Pregnancy
  • FAO recommends 4.5 of daily energy as EFA
    (essential fatty acids) in pregnancy and 6 in
    lactation
  • If kcals are inadequate energy based
    recommendations may be misleading

32
2002 DRI for n-6 Fatty Acids in Pregnancy
  • AI 13 g/day linoleic acid
  • Based on median linoleic acid intake of pregnant
    women in US where deficiency is basically
    non-existent.
  • AI for non-pregnant women 12 g/day

33
2002 DRI for N-3 Fatty Acids in Pregnancy
  • Demand driven by
  • fetus
  • placental tissue
  • secretion during lactation
  • AI 1.3 g/day of a-linolenic acid
  • Based on median a-linolenic acid intake of
    pregnant women in US where deficiency is
    basically non-existent.
  • non-pregnant AI1.1 g/day a-linolenic acid
  • DHA and EPA can contribute toward total n-3

34
Lipids Fetal
  • Human brain is lipid based 60 of dry weight
  • 30 of fetal CNS tissue is LCPUFA with n-3 to n-6
    ratio of 21
  • Fetal brain development starts early
    experiences growth spurt during last trimester
    and 1st 6 months of life
  • In 3rd trimester, storage of LCPUFA in fetal
    adipose tissue if adequate maternal sources

35
LCPUFA in Pregnancy
  • Eicosanoids derived from LCPUFA (prostaglandins,
    thromboxanes, prostacylcins, leukotrienes) play
    vital roles in pregnancy
  • Dietary sources of EFA - both n-3 and n-6 are
    important
  • The ideal ratio of n-3 to n-6 remains unknown

36
Are n-3 fatty acids essential nutrients for fetal
and infant development? (Nettleton, JADA 1993)
  • Fetal and infant nutrition may be enhanced by
    encouraging pregnancy and lactating women to
    consume seafood regularly (2-3 meals per week)
  • Poultry and plant sources of n-3 may be useful if
    seafood is impossible
  • Avoid extreme dietary rations of n-6 to n-3 by
    using olive and canola in addition to corn and
    safflower oil.

37
PIH and n-3 Fatty Acids
  • Possible biological pathway
  • Vasoconstriction and epithelial damage of PIH is
    associated with imbalance of TXA2
    (vasoconstrictor) and PGI2 (vasodilator)
  • If increased dietary intake of n-3
  • EPA competes with Arachadonic Acid for enzymes so
    may have lower production of TXA2 and higher
    production of PGI3 (vasodilator)

38
PIH and n-3 Fatty Acids
  • Epidemiological Studies
  • women with PIH may have lower levels of n-3
  • lower incidence of PIH in fish eating populations
  • Evidence is not strong and EBM reviews only
    mention that more work needs to be done in this
    area

39
N-3 and Prolonged Gestation
  • Faroe Islands
  • high birthweights
  • longer gestations
  • diet high in marine oils
  • Theory n-3 interference with uterine
    prostaglandin production

40
N-3 and Prolonged Gestation
  • Supplementation study
  • increased gestational length by 4 days
  • prolonged bleeding times increased blood loss
    at delivery

41
Essential Fatty Acids in Mothers and Their
Neonates (Hornstra, AJCN, 2000)
  • Maternal essential fatty acid status declines
    during pregnancy (absolute plasma levels
    in-crease, but non-essential increase more).
  • Pregnancy may cause maternal DHA
    depletion/mobilization from maternal stores.
    (Implications for close pregnancy spacing)

42
  • Essential PUFA status of newborns is restricted
    by that of the mother and may not be optimal.
  • Maternal PUFA supplementation affects neonatal
    PUFAQ status.
  • Maternal linoleate intake during pregnancy is
    negatively related to neonatal head
    circumference.
  • In preterm infants positive relationship between
    DHA in umbilical artery and birth weight. Length,
    and OFC.

43
Hornstra - Implications
  • Hunter-gatherer diet more rich in LCPUFA.
  • Humans evolved with limited ability to elongate
    and desaturate EFA?
  • Limitations require special consideration during
    increased requirements of fetal development,
    lactation, and neonatal development.

44
Trans Fatty Acids
  • Side product of catalytic hydrogenation of
    vegetable oils and biohydrogenation in the rumen
    of animals
  • Animal studies show discrimination against
    transport of trans FA across the placenta, but
    some are transported.
  • Trans FA inhibit elongation of EFA
  • Trans FA in plasma of human preterm infants was
    found to be inversely associated with LCPUFA

45
Trans Fatty Acids
  • Infant formula has few trans FA, breastmilk
    content reflects maternal diet.
  • What to recommend?

46
Trans Fatty Acids
  • It may be prudent to reduce maternal intake of
    trans fatty acids as much as possible, even if
    negative effects of trans fatty acids on fetal
    development cannot yet be ascertained.
  • Carlson et at. AJCN, 1997

47
Vitamins and Minerals
  • Increased needs in pregnancy associated with
  • DNA/RNA synthesis
  • Increased blood volume
  • bone mineralization structure
  • Increased energy needs

48
Vitamins and Minerals
  • Some nutrients of special concern due to low
    dietary levels in the population (from IOM
    report)
  • Vitamins B6, D, E
  • iron
  • calcium
  • zinc
  • magnesium

49
Vitamins and Minerals
  • Risks for low vitamin and mineral status include
  • low income
  • restricted energy intake
  • adolescence
  • vegan (Ca, B12, D, zinc)
  • Non white status (Ca)

50
Vitamins and Minerals
  • Vitamin and mineral needs are increased by
  • alcohol consumption
  • tobacco use
  • multiple fetuses
  • history of oral contraceptive use

51
Fat Soluble Vitamins
  • Placental transport is by simple diffusion, so
    fetus is not protected against high maternal
    intakes
  • Vitamin A is associated with multiple congenital
    anomalies
  • concerns appear to start at 8,000 IU
  • ACOG and AAP define excessive as gt 1,600 RE
    (twice the RDA)
  • 1 IU 0.3 RE all trans retinol

52
High levels of retinol intake during the first
trimester of pregnancy result from use of
over-the-counter vitamin/mineral supplements
(Voyles et al. JADA, Sept., 2000)
  • N64 women recruited at initial prenatal visit to
    obstetrics office in university town.
  • Household income and educational levels were
    higher than national averages.
  • Women completed questionnaires and three day food
    records.
  • 2 physicians in office prescribed routine
    prenatal vitamins, the third did not.

53
Voyles, cont. - Adherence
  • 23 who were prescribed vitamins did not take
    them.
  • 26 who were prescribed vitamins took OTC
    supplements instead.
  • 58 of those who were not prescribed took over
    the counter supplements.
  • 9 of 10 women who had excessive intakes took OTC
    supplements

54
Voyles, Retinol Intakes (n64)
  • 20 had intakes lt 800 RE
  • 34 had intakes between 800 and 1,600 RE
  • 10 had intakes gt 1,600 RE
  • Mean intake of vitamin A from food sources alone
    was 159 of the RDA

55
Voyles, Applications
  • Most women can meet vitamin A needs with food
    alone.
  • Supplements need to be carefully considered
  • many women taking OTC supps before pregnancy
  • IOM recommendation is to avoid supps with vitamin
    A in first trimester

56
Fat Soluble Vitamins, cont.
  • Vitamin D
  • toxic levels 2000 IUs (50 micrograms) per day
  • Associated with fetal hypercalcemia, aortic
    stenosis, abnormal skull development/premature
    closure of fontanel

57
Water Soluble Vitamins - C
  • Potential for dependency in the newborn (reported
    with vitamin C and B6)
  • Vitamin C is actively transported across placenta
    as well as simple diffusion so potential for high
    fetal levels exists
  • High maternal vitamin C levels associated with
    false positive tests for urinary glucose as well
    as cramps, nausea, and diarrhea

58
Water Soluble Vitamins - B6
  • Inconclusive studies have linked to
  • depression in pregnancy
  • decreased apgars with low maternal status
  • one study found good results for women with
    severe nausea who were treated with 25 mg each 8
    hours
  • toxicity reported at gt 200mg (neuropathy)

59
Folic Acid - NTD
  • NTD - 2,500 births per year in US.
  • 50-70 may be preventable with adequate maternal
    folic acid status.
  • Etiologies and pathways remain unknown.
  • Some population groups - Mexican Americans,
    Native Americans - at higher risk.

60
Folic Acid - Recommendations
  • 1992 - USPHSD women of childbearing age consume
    400 mcg folic acid per day.
  • 1998 - IOM women consume 400 mcg synthetic
    folic acid per day from supplements or fortified
    foods.
  • January 1998 - USFDA fortification of the food
    supply at 140 mcg/100 grams of flour.

61
Folic Acid Fortification
  • 0.14 mg per 100g cereal grain products
  • 0.035 mg per slice of bread
  • 0.10 mg per serving breakfast cereal
  • Low level consumers with intakes of 0.23-0.25 mg.
  • Women with low intake range of food guide pyramid
    will consume 0.5 mg per day total folate.

62
Folic Acid Supplements
  • Dietary folate is about half as absorbable as
    synthetic folic acid.
  • Public health recommendations have focused on
    message to all women of childbearing age to take
    a supplement of synthetic folic acid.

63
MMWR - Knowledge and use of folic acid,
1995-1997. Random digit dialing to 2000 women,
ages 18-45
64
Dietary Reference Intakes for Thiamin,
Riboflavin, Niacin, Vitamin B6, Folate, Vitamin
B12, Pantothenic Acid, Biotin, and Choline (1999)
65
Dietary Reference Intakes for Thiamin,
Riboflavin, Niacin, Vitamin B6, Folate, Vitamin
B12, Pantothenic Acid, Biotin, and Choline (1999)
66
Iron
  • Routine Supplementation
  • Screening
  • Treatment for Iron Deficiency Anemia

67
US Preventative Services Task Force
  • Prevalence Hgb lt 10 g/dl is present in 20-40
    of pregnant women, due largely to expansion of
    blood volume.
  • Burden observational data confirms modest
    associations between severe anemia and adverse
    maternal and infant outcomes.
  • Efficacy Trials find improved hematological
    indices not improved clinical outcomes

68
US Preventative Services Task Force Iron
Supplementation in Pregnancy
  • Safety Unintentional overdosing,
    hemochromatosis, GI symptoms
  • Compliance Prescribed Fe supps taken correctly
    by 70, not at all by 10
  • Recommendation Evidence is insufficient to
    recommend for or against routine iron
    supplementation during pregnancy.

69
IOM
  • Pregnancy requires an additional 6 mg Fe/day in
    T2 and T3
  • Fe deficiency is common in pregnancy
  • Fe supps maintain Hgb levels during pregnancy.
  • Percentage of iron absorbed declines as the
    amount given increases.
  • High does increase side effects and decrease
    compliance.
  • Recommendation Small dose (30mg) after 12 weeks
    for all pregnant women.

70
Cochrane Review of 20 Trials- 1999
  • Iron supplementation appears to prevent low
    haemoglobin at birth or at six weeks
    post-partum.
  • Iron supplementation had no detectable effect on
    any substantial measures of either maternal or
    fetal outcome.

71
Recommendations for Routine Iron Supplementation
in Pregnancy
72
Iron US Preventative Health Services Task Force
(1997) Screening
  • Screening for iron deficiency anemia using
    hemoglobin or hematocrit is recommended for
    pregnant women and for high-risk infants
  • The exact prevalence of iron deficiency anemia
    among pregnant women is uncertain
  • lt2 of nonpregnant women aged 20-44 years may
    have iron deficiency anemia.
  • low-income, pregnant U.S. populations a low
    hemoglobin level and/or low hematocrit is present
    in 6 of white women and 17 of black women
    during the first trimester and in 25 of white
    women and 46 of black women during the third
    trimester.7

73
Iron US Preventative Health Services Task Force
(1997) Screening
  • The high rates of anemia in pregnant women may
    not be attributable to iron deficiency, however.
    In a large cohort of urban, low-income, mostly
    minority pregnant women, only 12.5 of anemic
    women were iron deficient
  • Screening criteria for pregnancy
  • WHO menstruating women, lt12 g/dL pregnant
    women, lt11 g/dL
  • CDC lt11 g/dL during the first and third
    trimesters and lt10.5 g/dL in the second trimester

74
Iron US Preventative Health Services Task Force
(1997) Screening
  • There is little evidence evaluating adverse
    effects from the mild degree of anemia that is
    most often detected by screening asymptomatic
    persons in developed countries.
  • In a Swedish cohort, anemic women (Hgb lt12 g/dL)
    reported no increase in reported infections,
    fatigue, or other symptoms, but they were
    significantly more likely to report low work
    productivity compared to nonanemic women.
  • In a small, randomized placebo-controlled trial
    of Welsh women with anemia (hemoglobin lt10.5
    g/dL) detected by population-based screening,
    iron therapy did not result in clinically or
    statistically significant improvements in
    psychomotor function tests, symptoms, or
    subjective well-being, despite increased
    hemoglobin concentrations.

75
Iron US Preventative Health Services Task
Force Screening
  • A hemoglobin analysis or hematocrit is
    recommended for pregnant women at their first
    prenatal visit
  • There is insufficient evidence to recommend for
    or against repeated prenatal testing for anemia
    in asymptomatic pregnant women lacking evidence
    of medical or obstetrical complications
  • Compared to other diagnostic tests, serum
    ferritin has the best sensitivity and specificity
    for detecting iron deficiency in patients found
    to be anemic.

76
Iron Deficiency Anemia Recommended Guidelines
for the Prevention, Detection, and Management
Among U.S. Children and Women of Childbearing Age
(1994) Institute of Medicine (IOM)
  • A. Screen for anemia at the first prenatal visit
    and treat as appropriate
  • 1. If T1, Hgb ferritin Future eval if Hgb lt
    9.0 g/dl or between 9.0 and 10.9 with ferritin gt
    30
  • 2. Do not treat with Fe when Hgb gt 11.0 g.dl and
    serum ferritin is gt 20 mcg/l
  • 3. 30 mg Fe supp. If Hgb between 9.0-10.9 and
    ferritin 12-20 or Hgb gt 11.0 and ferritin , 20 lt
    20

77
Iron Deficiency Anemia Recommended Guidelines
for the Prevention, Detection, and Management
Among U.S. Children and Women of Childbearing Age
(1994) Institute of Medicine (IOM)
  • 4. 60-120 mg Fe if Hgb 9.0-10.9 and ferritin is
    lt 12
  • 5. If no response to Fe supp. Refer for
    additional eval.
  • Note Blacks Hgb 0.80 less, also adjust for high
    altitude and cigarette smoking

78
Iron Deficiency Anemia Recommended Guidelines
for the Prevention, Detection, and Management
Among U.S. Children and Women of Childbearing Age
(1994) Institute of Medicine (IOM)
  • B. Screen for anemia at the second trimester
    visit and treat as appropriate
  • Recommendation for supplement and referral
    are similar to first trimester, but upper Hgb
    cutoffs are 10.4 for upper level of
    supplementation and 10.5 for lower

79
Iron Deficiency Anemia Recommended Guidelines
for the Prevention, Detection, and Management
Among U.S. Children and Women of Childbearing Age
(1994) Institute of Medicine (IOM)
  • C. Screen for anemia at the third trimester
    visit and treat as appropriate
  • D. Screen high-risk women for anemia at the 4-6
    week postpartum visit
  • E. Advise on diet at each prenatal visit
  • 1. Eat a varied diet of iron

80
Iron Deficiency Anemia Recommended Guidelines
for the Prevention, Detection, and Management
Among U.S. Children and Women of Childbearing Age
(1994) Institute of Medicine (IOM)
  • E. Advise on diet at each prenatal visit
  • 1. Eat a varied diet of iron rich foods
  • 2. Items that inhibit absorption of iron (tea,
    coffee, whole-grain cerealsparticularly bran,
    unleavened whole-grain breads and dried beans)
    should be consumer separately from iron rich
    foods.

81
Zinc - Adapted from Janet King 1999
  • Severe maternal zinc deficiency is teratogenic in
    rats
  • Zinc is available to the fetus from maternal
    tissues
  • Both survey and experimental research on zinc in
    human pregnancy have inconclusive results due to
    issues of study design

82
Zinc - cont.
  • Kirksey et al. AJCN, 1994
  • Low income Egyptian women
  • Only 2 mg zinc available when look at
    phytate-zinc molar ratio
  • 20 of variance of birthweight attributed to
    plasma Zn in second trimester
  • 39 of variance of birthweight attributed to
    maternal weight at 3 mos. gest.... and plasma Zn
    in second trimester

83
Zinc
  • Poor maternal zinc status
  • limits fetal growth
  • influences length of gestation
  • increases risk of maternal complications

84
Zinc Absorption in Pregnancy(Fung et al, AJCN,
1997)
85
Zinc Absorption
  • Reduced by
  • phytate
  • supplemental iron
  • GI diseases
  • Crohns
  • diarrhea disease
  • intestinal by-pass

86
Zinc metabolism
  • Needs increased by hepatic sequestering and
    increased urinary losses
  • trauma
  • infection
  • smoking
  • alcoholism
  • chronic strenuous exercise

87
Cochran Collection Zinc, May 1997
  • Background and objectives It has been suggested
    that low serum zinc levels may be associated with
    abnormalities of labor, although this has not yet
    been established. The objective of this review
    was to assess the effect of zinc supplementation
    in pregnancy on maternal and fetal mortality and
    morbidity.

88
Cochran Collection Zinc
  • Main results Five trials were included. Apart
    from possible reduction in induction of labor in
    the supplemented group, no differences were
    detected between routine supplementation of zinc
    and placebo or no zinc in pregnancy.

89
Cochran Collection Zinc
  • Reviewers' conclusions There is not enough
    evidence to evaluate the use of routine zinc
    supplementation in pregnancy

90
Calcium
  • Fetus requires 25 to 30 g calcium
  • Most fetal calcium accretion in third trimester
  • Maternal absorption, increases early in pregnancy
    and maternal Ca stores increases in preparation
    for third trimester demands
  • 1,25(OH)2D concentrations increase in pregnancy

91
Calcium Absorption
92
A longitudinal study of calcium homeostasis
during human pregnancy and lactation (Ritchie et
al, AJCN, 1998)
  • N14, white, middle-upper income well nourished
    women who consumed 1200 g Ca daily
  • Exams
  • prepregnancy
  • T1 (8-10 weeks of pregnancy
  • T2 (23-26 weeks)
  • T3 (34-36 weeks)
  • EL (6-10 weeks postpartum)
  • 5-2 months post menses

93
(No Transcript)
94
Dietary Reference Intakes for Calcium,
Phosphorus, Magnesium, Vitamin D, and Fluoride
(1999)Institute of Medicine (IOM
  • Dietary calcium intake does not appear to
    influence changes in maternal bone mass during
    pregnancy
  • There is a lack of a relationship between the
    number of previous pregnancies and BMD.
  • Some studies find a positive relationship between
    number of children born and radial BMD, total
    body calcium, and risk of hip fracture.

95
Dietary Reference Intakes for Calcium,
Phosphorus, Magnesium, Vitamin D, and Fluoride
(1999)Institute of Medicine (IOM
  • Adaptive maternal responses to fetal calcium
    needs include an enhanced efficiency of
    absorption, which is modulated through changes in
    calciotropic hormones. Thus, provided that
    dietary calcium intake is sufficient for
    maximizing bone accretion rates in the
    nonpregnant state, the AI does not have to be
    increased during pregnancy.

96
Dietary calcium and pregnancy-induced
hypertension is there a relation?
  • Ritchie LD, King, JC. Am J Clin Nutr.
    200071(suppl)1371S-4S

97
Effect of routine calcium supplementation during
pregnancy on relative risk (RR) of preeclampsia
Subgroup Typical RR (95 CI) Low-risk (n 6
trials) 0.79 (0.65, 0.94) High-risk2 (n 4
trials) 0.22 (0.11, 0.43) Adequate-calcium
diet 0.86 (0.71, 1.05) (900 mg/d)(n 4
trials) Low-calcium diet (lt900 mg/d) (n 6
trials) 0.32 (0.21, 0.49) Those at high
risk teenagers, had had preeclampsia previously,
had increased sensitivity to angiotension II, or
had preexisting hypertension.
98
Effect of routine calcium supplementation during
pregnancy on relative risk (RR) of high blood
pressure Subgroup Typical RR (95
CI) Low-risk (n 6 trials) 0.84 (0.76,
0.92) High-risk2 (n 3 trials) 0.35 (0.21,
0.57) Adequate-calcium diet (900 mg/d) (n 4
trials) 0.90 (0.81, 0.99) Low-calcium diet
0.49 (0.38, 0.62) (lt900 mg/d) (n 5
trials) .
99
Review Conclusions
  • Ca supplementation during pregnancy for women
    with deficient calcium intake is a promising
    preventive strategy for preeclampsia.

100
Dietary Reference Intakes for Calcium,
Phosphorus, Magnesium, Vitamin D, and Fluoride
(1999)Institute of Medicine (IOM)
101
Calcium IOM Recommendations
  • If intake is lt 600 mg
  • Encourage increased dietary sources
  • Consider supplemental calcium

102
Cochran Collection Magnesium
  • Background and objectives Many women, especially
    those from disadvantaged backgrounds, have
    intakes of magnesium below recommended levels.
    Magnesium supplementation during pregnancy may be
    able to reduce fetal growth retardation and
    pre-eclampsia, and increase birthweight. The
    objective of this review was to assess the
    effects of magnesium supplementation during
    pregnancy on maternal, neonatal and pediatric
    outcomes.

103
Cochran Collection Magnesium
  • Main results Six trials involving 2637 women
    were included. Only one of these trials was
    judged to be of high quality. Compared with
    placebo, oral magnesium treatment from before the
    25th week of gestation was associated with a
    lower incidence of preterm birth (odds ratio
    0.71, 95 confidence interval 0.52 to 0.95).
    There was also less maternal hospitalization
    during pregnancy, fewer cases of antepartum
    hemorrhage, a lower incidence of low birthweight
    and small for gestational age infants. Poor
    quality trials are likely to have resulted in a
    bias favoring magnesium supplementation.

104
Cochran Collection Magnesium
  • Reviewers' conclusions There is not enough high
    quality evidence to show that dietary magnesium
    supplementation during pregnancy is beneficial.
About PowerShow.com