A young fertile couple's chance of conceiving in
the first month they try is 25%-30%. By the end of the first year, about
85% of couples achieve a success; the remaining 15% are diagnosed with
infertility.
Infertility has many known causes (eg, ovulatory
defect, tubal occlusion, low sperm counts), and many factors lower the chance
of pregnancy (eg, older age, lower ovarian reserve, endometriosis). There are
modifiable and nonmodifiable risk factors for infertility or reduced fertility.
Although some factors can't be altered (eg, age and ovarian reserve), others,
such as body weight and lifestyle habits, are modifiable.
Patients frequently ask providers to offer them
guidance on the ideal diet to improve their chances of conceiving and carrying
a pregnancy to term. A recent review by Chiu and colleagues summarizes the
available epidemiologic literature on the reproductive benefits of diets and
dietary supplements.
Nutrition and Fertility: Review Findings
This article reviews the potential benefits of
consumption of certain micronutrients, macronutrients, and dietary patterns.
The following conclusions are drawn from this review:
Folic acid. Folic acid is
important for germ cell production and pregnancy. The recommended daily dose to
prevent neural tube defects is 400-800 µg. Women who take folic acid-containing
multivitamins are less likely to be anovulatory, and the time to achieve a pregnancy
is reduced. Those who consume more than 800 µg of folic acid daily are more
likely to conceive with assisted reproductive technology (ART) than those whose
daily intake is less than 400 µg.
Vitamin D. Vitamin D may affect
fertility through receptors found in the ovaries and endometrium. An extremely
low vitamin D level (< 20 ng/mL) is associated with higher risk for
spontaneous miscarriage risk. Some reports suggest that women with adequate
vitamin D levels (> 30 ng/mL) are more likely to conceive after ART when
compared with those whose vitamin D levels are insufficient (20-30 ng/mL), or
deficient (< 20 ng/mL). These findings, however, are inconclusive.
Carbohydrates. Dietary
carbohydrates affect glucose homeostasis and insulin sensitivity, and by these
mechanisms can affect reproduction. The impact is most pronounced among women
with polycystic ovary syndrome (PCOS). In women with PCOS, a reduction in
glycemic load improves insulin sensitivity as well as ovulatory function. Whole
grains have antioxidant effects and also improve insulin sensitivity, thereby
positively influencing reproduction.
Omega-3 supplements. Omega-3
polyunsaturated fatty acids lower the risk for endometriosis. Increased levels
of omega-3 polyunsaturated fatty acids are associated with higher clinical
pregnancy and live birth rates.
Protein and dairy. Some reports suggest
that dairy protein intake lowers ovarian reserve. Other reports suggest improved
ART outcomes with increased dairy intake. Meat, fish, and dairy products,
however, can also serve as vehicles for environmental contamination that may
adversely affect the embryo. Fish, on the other hand, has been shown to exert
positive effects on fertility.
Dietary approach. In general, a
Mediterranean diet is favored (high intake of fruits, vegetables, fish,
chicken, and olive oil) among women diagnosed with infertility.
Viewpoint
A well-balanced diet, rich in vegetables and
fruits, is preferred for infertile women and should provide the required micro-
and macronutrients. It remains common for patients consume a wide variety of
vitamin, mineral, and micronutrient supplements daily. Supplements should
not replace food sources of vitamins and trace elements because of differences
in bioavailability (natural versus synthetic), and inaccuracy of label
declarations may result in suboptimal intake of important nutrients. Furthermore,
naturally occurring vitamins and micronutrients are more efficiently absorbed.
With respect to overall diet, women are advised to
follow a caloric intake that won't contribute to being overweight or obese.
Obesity is on the rise among younger people, including children. Obese women
have a lower chance of conceiving and are less likely to have an uncomplicated
pregnancy. Proper weight can be maintained with an appropriate diet and regular
exercise.
Finally, women must abstain from substances that
are potentially harmful to pregnancy (eg, smoking, alcohol, recreational drugs,
high caffeine intake).
References
1. Zinaman MJ, Clegg ED,
Brown CC, O'Connor J, Selevan SG. Estimates of human fertility and pregnancy
loss. Fertil Steril. 1996;65:503-509. Abstract
2. Practice Committee of
American Society for Reproductive Medicine. Definitions of infertility and
recurrent pregnancy loss: a committee opinion. Fertil Steril. 2013;99:63. Abstract
3. Chiu YH, Chavarro JE,
Souter I. Diet and female fertility: doctor, what should I eat? Fertil Steril.
2018;110:560-569. Abstract
4. Kantor ED, Rehm CD,
Du M, White E, Giovannucci EL. Trends in dietary supplement use among US adults
from 1999-2012. JAMA. 2016;316:1464-1474. Abstract
5. Carr AC, Vissers MC.
Synthetic or food-derived vitamin C—are they equally bioavailable? Nutrients.
2013;5:4284-4304. Abstract
6. Yetley EA. Multivitamin
and multimineral dietary supplements: definitions, characterization,
bioavailability, and drug interactions. Am J Clin Nutr. 2007;85:269S-276S. Abstract
7. Practice Committee of
American Society for Reproductive Medicine. Obesity and reproduction: an
educational bulletin. Fertil Steril. 2008;90(5 Suppl):S21-S29. Abstract
Medscape
Peter Kovacs, MD, PhD.
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