Fertility Flashcards
What are obesity and chronic stress linked to?
Obesity and chronic stress are linked to dysregulation of the hypothalamus-pituitary and ovaries axis.
What is obesity linked to?
Obesity is linked to:
* Impairment of ovarian follicle development
* Defects of oocyte maturation
* Altered fertilisation
* Disrupted meiosis and mitochondrial dynamics derangements leading to abnormal embryo preimplantation
What did Rich-Edwards et al. (2002) find about BMI and fertility?
Rich-Edwards et.al (2002) found that there was an association between infertility and BMI below 20kg/m2 and above 20kg/m2.
What is anovulation?
Anovulation:
* when an egg (ovum) doesn’t release from the ovary during the menstrual cycle
What did the Health Survey for England (2019) find in regards to obesity and fertility?
The Health Survey for England (2019) found that obesity is associated with:
* Increased prevalence of miscarriage
* Chronic anovulation (no ovulation, egg isn’t released from the ovary during the menstrual cycle)
How much greater is the risk for infertility in obese women in comparison to non-obese women?
Infertility risk is 3 times greater in obese women than in non-obese women.
What is obesity a major risk determinant for?
Obesity is a major risk determinant for polycystic ovary syndrome.
Obesity and fertility
- Obesity: High BMI above 24 kg/m2 increased risk of ovulatory infertility.
- Impairment of ovarian follicle development
- Defects of oocyte maturation
- Altered fertilisation
- Disrupted meiosis and mitochondrial dynamics derangements leading to abnormal embryo preimplantation
- Increased prevalence of miscarriage
- Chronic anovulation
- Associated with amenorrhoea, the absence of menstrual periods.
- Leptin secreted from adipose tissue. Leptin concentrations are higher in obese but leptin plays a role in fertility regardless of this as concentrations change depending on point in cycle.
- High leptin concentrations in obesity inhibits action of leptin and stops it from stimulating the hypothalamus-pituitary-ovary access and leads to the problems with fertility.
- Risk of infertility is x3> in obese than in non-obese women
- Overweight and obesity associated with negative outcomes for patients undergoing IVF
- Poor oocyte quality, lower preimplantation rate and uterine receptivity
Body fat and fertility
Body fat and fertility
* Being undernourished/underweight can affect fertility
* High intensity sport/dance linked to delayed menarche with an increased risk of amenorrhoea/anovulation
* 22% minimum fat needed for stable menstrual cycle
* 17% minimum body fat needed to trigger menarche
* Excess body fat can also affect fertility
* Fatness gives an indication of whether a women’s body could support a pregnancy as well as breast feed.
Underweight and fertility
Underweight and fertility
* Increased risk of infertility if BMI < 20kg/m2
* Associated with amenorrhoea, the absence of menstrual periods.
* 10-15% of weight loss for height is also associated with menstrual cycle issues.
* 22% body fat is minimum amount stable reproductive cycling.
* But 17% is required for menarche.
* Fatness gives an indication of whether a women’s body could support a pregnancy as well as breast feed.
Male fertility
Male fertility
* Unhealthy dietary patterns, alcohol, zinc deficiency, oxidative stress and obesity connected to infertlity
* Male obesity and overweight associated with reduced sperm quality and quantity
Low plasma testosterone → impaired spermatogenesis
* Heavy alcohol consumption
Linked with reducedtestosteroneproduction and impotence and decreased spermatogenesis
* Zinc deficiency impairs sperm production
Supplementation increases sperm count in sub-fertile men but rarely to the extent required to be classified normal (>20 million cells/ml)
* Sperm highly sensitive to oxidative stress
Mixed results of antioxidant supplementation – mostly trials have shown limited or negative results
Folic acid supplementation
Folic acid supplementation:
* all women planning a pregnancy to take a daily supplement of folic acid 400micrograms (0.4mg).
* from the time contraception stops, or as soon as they find out they are pregnant, until week 12 of pregnancy.
* this is to prevent neural tube defects
Polycystic ovary syndrome
Polycystic ovary syndrome:
* Linked to infertility: anovulatory, infrequent periods, oligorrhoea
* High luteinizing hormone
* Symptoms: hirsutism, infertility, head hair loss, acne
* Linked to obesity and family history
* Abdominal fat deposition linked to insulin resistance
* Insulin resistance inhibits synthesis of sex hormone binding globulin in liver, deficiency of SHBG increases androgens
* 50% of sufferers are obese
* Obesity increases androgens
* L-carnitine and co-enzyme Q may help infertility
* Treatment: physical activity, weight loss, dietary change + metformin.
* Weight loss linked to: reduced hirsutism, partial menstrual cycle restoration, reduced insulin concentrations, reduced testosterone concentrations.
Dietary patterns and fertility
Dietary patterns and fertility:
* High consumption of whole grains, monounsaturated or polyunsaturated oils, vegetables, fruits, and fish has been associated with improved fertility in women and higher semen quality in men
* Mediterranean diet linked with:
1. higher fertility and live birth among non-obese
2. improved measures of semen quality
3. improved chances of pregnancy
Nutritional components linked to optimal male fertility
Nutritional components linked to optimal male fertility:
* Omega 3 fatty acids: protective against sperm DNA fragmentation, testosterone and testicular volume
* Low glycaemic load and high whole grain content might promote fertility
* Antioxidant supplementation may improve sperm quality
* Vitamin D: may increase sperm quality and motility
* Vitamin B12: may increase sperm count, motility and minimize sperm DNA damage
* Zinc supplementation: may increase sperm quality in infertile males
Which 3 nutrients may help infertility in PCOS?
L-carnitine, vitamin D and co-enzyme Q may help infertility in PCOS
What are good sources of folic acid?
Good sources of folic acid:
* Leafy greens: spinach, kale, brussel sprouts (100ug), cabbage,
* Broccoli
* Beans and legumes
* Beef extracts and yeast
* Oranges (54ug medium) and orange juice
* Wheat bran and other wholegrain foods
* Poultry
* Pork
* Shellfish
* Liver
* Fortified foods
* 4g of marmite= 100ug
* 1 cup of horlicks= 60ug
If there is a family history of neural tube defects, the mother has diabetes or her BMI is >30, what is the advised amount for folic acid supplementation?
If there is a family history of neural tube defects, the mother has diabetes or her BMI is >30: 5milligrams (5000ug) of folic acid should be taken per day.
Describe the importance of increasing folic acid intake to reduce the risk of embryonic malformation
Describe the importance of increasing folic acid intake to reduce the risk of embryonic malformation:
- Low intakes of folic acid are linked to neural tube intakes.
- Folates may be related to NTD risk through their roles in nucleotide synthesis.
- Examples: spina bifida and anencephaly, developed during embryonic development.
- Neural tube defects can be caused by genetic and environmental factors.
- It is difficult for women to get the recommended amount of 400ug/day from foods that aren’t fortified with folic acid
- Studies have shown that high folic acid intakes reduce neural tube defect incidences.
- Prior to the implementation of 400ug being advised by the DoH there were more incidences of neural tube defects
- Folic acid intake is reported in only 28% of women in England, below desired amount.
- 2021: Mandatory fortification of non-wholemeal wheat flour in the UK
When are women advised to take folate supplements (400micrograms or 5000micrograms)?
- all women planning a pregnancy to take a daily supplement of folic acid 400micrograms (0.4mg) (5000micrograms if >30 kg/m2, have family history or diabetes).
- from the time contraception stops, or as soon as they find out they are pregnant, until week 12 of pregnancy.
- this is to prevent neural tube defects
Which lifestyle factors can affect fertility?
Lifestyle factors that can affect fertility:
* Caffeine consumption: infertility in animal studies. >8 cups of coffee a day. Higher caffeine intakes associated with higher risk of spontaneous abortion
* Alcohol intake: associated with increased risk of ovulatory infertility and endometriosis. Alcohol crosses the placenta. Impairs antioxidant capacity, increases free radicals and ROS, increases apoptosis in brain tissue.
* Adiposity: underweight or overweight/obese: anovulation, dysregulation of the hypothalamus-pituitary-ovary axis,
* Stress
* Smoking: can cause miscarriage or stillbirth, increase risk of birth defects, delay conception, deplete ovarian follicles
* Environmental pollutants: phytodrugs, heavy metals can affect fertility
Which factors are associated with infertility in men?
Unhealthy dietary patterns, alcohol, zinc deficiency, oxidative stress and obesity connected to infertlity in men
Dietary factors associated with infertility in women
- Caffeine consumption: infertility in animal studies. >8 cups of coffee a day. Higher caffeine intakes associated with higher risk of spontaneous abortion
- Alcohol intake: associated with increased risk of ovulatory infertility and endometriosis. Alcohol crosses the placenta. Impairs antioxidant capacity, increases free radicals and ROS, increases apoptosis in brain tissue.
- High fat dairy products might increase risk of infertility
Acute undernutrition and fertility
- Acute under-nutrition decreases fertility
- (via modifying hormonal signals that regulate ovulation/menstrual cycle
- impair sperm maturation impairment in males)
- acute, severe food shortages during World War II -reduction in birth rate
- 1942 in Russia during Leningrad siege - acute food shortages - high rates of amenorrhea
Chronic undernutrition and fertility
Chronic undernutrition and fertility
* Chronic under-nutrition does not have a big impact on fertility
* in developing countries with insufficient dietary nutrients and energy/malnutrition: high birth rate but high infant mortality
* During World War II, Japanese occupation of Singapore, severe prolonged food shortages - fertility not impaired
Explain the role of undernutrition on female fertility (acute/chronic)
Acute undernutrition:
* decreases fertility via impairment of sperm maturation in males and modifying hormonal signals that regulate ovulation/menstrual cycle
* during World War II severe food shortages led to lower birth rates
* in Russia during Leningrad siege - acute food shortages - high rates of amenorrhea
Chronic undernutrition:
* Doesn’t affect fertility but it does increase infant mortality rates
* In developing countries with insufficient dietary nutrients and energy/malnutrition: high birth rate but high infant mortality
* During World War II, Japanese occupation of Singapore, severe prolonged food shortages - fertility not impaired
Discuss the impact of obesity and underweight on female fertility
Obesity and female fertility:
* Risk of infertility is x3> in obese than in non-obese women
* High BMI above 24 kg/m2 associated with increased risk of ovulatory infertility.
* Impairment of ovarian follicle development
* Defects of oocyte maturation
* Altered fertilisation
* Disrupted meiosis and mitochondrial dynamics derangements leading to abnormal embryo preimplantation
* High leptin concentrations in obesity inhibits action of leptin and stops it from stimulating the hypothalamus-pituitary-ovary access and leads to the problems with fertility.
* Overweight and obesity associated with negative outcomes for patients undergoing IVF: Poor oocyte quality, lower preimplantation rate and uterine receptivity
Underweight and female fertility:
* Increased risk of infertility with BMI < 20 kg/m2
* Associated with amenorrhoea, the absence of menstrual periods.
* 10-15% of weight loss for height is also associated with menstrual cycle issues.
* 22% body fat is minimum amount stable reproductive cycling.
* But 17% is required for menarche.
* Fatness gives an indication of whether a women’s body could support a pregnancy as well as breast feed.
Definition of fertility
Fertility is the ability to conceive a child
Appraise the evidence regarding dietary patterns and common agents (e.g., alcohol and caffeine) on female fertility
Appraise the evidence regarding dietary patterns and common agents (e.g., alcohol and caffeine) on female fertility
* Caffeine:
* Evidence is inconclusive.
* High intakes >8 cups associated with infertility
* Most studies associated with animals
* A study showed high caffeine intakes associated with miscarriage.
* Advised to limit to 200mg per day
* Alcohol:
* Associated with increased risk of ovulatory infertility and endometriosis that is associated with infertility
* Effects might be confounded by other factors
* Can be harmful to the foetus
* ‘Women who are pregnant or planning a pregnancy are advised to stop drinking alcohol altogether’
* Promote fertility
* Diet can have a positive effect on fertility: dietary fibre rich, omega 3FAs, vegetable protein, vitamins and minerals (Skoracka et al, 2021)
* NHS advise to follow general healthy eating advice
* Zinc and folic acid might reduce risk of ovulatory infertility
* Zinc and selenium supplements might reduce time to pregnancy and risk of subfertility
Describe the impact of dietary components and overweight on male infertility
Describe the impact of dietary components and overweight on male infertility
* Overweight:
* associated with reduced sperm quality and quantity due to low plasma testosterone → impaired spermatogenesis.
* Zinc:
* Zinc deficiency impairs sperm production
* Supplementation increases sperm count in sub-fertile men but rarely to the extent required to be classified normal (>20 million cells/ml)
* ** Alcohol:**
* Heavy alcohol consumption linked with reducedtestosteroneproduction and impotence and decreased spermatogenesis
*
- To promote:
- Fruit and vegetable intake important for sperm health
- Healthy eating patterns associated with good semen quality and fecundity
- Vitamin B12 might increase sperm count, motility and minimize sperm DNA damage
- Omega 3 fatty acids might be supportive
- Low glycaemic load and high whole grains might be protective
- Antioxidant supplementation improves semen quality and may increase clinical pregnancy probability and live birth
Alcohol consumption and impact on foetus
Alcohol consumption and impact on foetus
* Alcohol crosses placenta
* Foetus exposed to higher concentrations due to accumulation in the amniotic fluid and reduced foetal metabolic enzyme activity
* Impaired antioxidant capacity
* ↑ free radicals and reactive oxygen species (ROS)
* ↑ apoptosis in brain tissue
