Download Iron intake and risk of ovulatory infertility: a journal report

IRON INTAKE AND RISK OF
OVULATORY INFERTILITY:
A JOURNAL REPORT
Clerk Maria Karla L. Guinto
Infertility

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Results in important emotional distress among those
affected
Identification of modifiable risk factors could lead
to effective interventions for prevention
Iron deficiency and infertility
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Women with iron and other micronutrient deficiency
have delayed menarche, early menopause and
infertility of unknown cause
Resumption of fertility in women with low body iron
stores receiving iron supplements
Iron-containing supplement given to women who had
unsuccessfully tried to be pregnant documented a
higher pregnancy rate
General objective
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To evaluate whether iron supplement use or greater
intake of total, heme, and nonheme iron is
associated with lower risk of ovulatory infertility
Methodology
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Duration of the study: 8 years
Inclusion criteria:
 Female,
24 to 42 years old
 Married
 With
available dietary information
 Without a history of infertility
 Tried to become pregnant or became pregnant
between 1991 and 1999
 Nondiabetic
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Dietary information was collected in 1991 and
1995 using a semiquantitative food frequency
questionnaire
 How
often they consumed each of the foods and
beverages included in the questionnaire
 Use of multivitamins and other nutrient supplements
 Daily dose of iron intake
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18,555 subjects
Divided into users and nonusers of iron supplements
Users further divided into:
Using a supplement with low iron content (<51 mg/d
for 1991 questionnaire, <41 mg/d for 1995)
 With high iron content (≥51 mg/d for 1991, ≥41
mg/d for 1995)
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Relative risk of ovulatory infertility according to
categories of iron intake and iron supplement use
was estimated
Potential confounders: BMI, parity, smoking history,
physical activity, history of contraceptive use,
dietary factors, intakes of alcohol, coffee,
multivitamins, retinol, a-carotene, vitamin C
Results
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Use of iron supplements was associated with
approximately one half the risk of developing
ovulatory infertility compared with non-use of these
supplements
Women consuming iron supplements with low iron
content had similar risk of ovulatory infertility as
nonusers
Consumption of supplements with high iron content
was associated with a 70% lower risk of ovulatory
infertility (95% confidence interval)
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Heme iron intake was associated with an increased
risk of ovulatory infertility
Total and nonheme iron intakes were inversely
related
Women with highest intake of heme iron has a 31%
greater risk of ovulatory infertility (95% CI)
Those with the highest category of nonheme intake
had 40% lower risk of ovulatory infertility when
compared with those in the lowest category
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No evidence of interaction of Vitamin C intake with
iron supplement use, heme iron intake or nonheme
iron intake
No interactions between intake of these kinds of
iron and menstrual cycle length or history of
contraceptive use
Not associated with age, BMI or parity
Discussion
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Iron deficiency is the most prevalent nutritional
deficiency worldwide.
Women of child bearing age are at increased risk
of this condition.
Iron supplements have been associated with lower
prevalence of iron deficiency among women of
reproductive age.
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Granulosa cells can synthesize transferrin, which
may be translocated to the oocytes
Transferrin and its receptor may be redundant in
the ovary or do not play an important role in local
iron metabolism. However, these proteins are
essential for ovum development and are required to
support the increasing iron demand of the
developing follicle.
Limitations of the study
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Not a cohort of women known to be planning a
pregnancy
Included only married women whose pregnancies
are more likely to be intentional than those of
umarried women
Conclusion
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Use of iron supplements with high iron content was
associated with a reduced risk of ovulatory
infertility
Inverse relationship between nonheme iron intake
and risk of ovulatory infertility due to the use of
supplements containing iron
Women planning to be pregnant should consider
using iron supplements because these may help
them prevent iron deficiency and improve fertility
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