L2 Nutrition Prior to Pregnancy Flashcards
What organ releases GnRH?
hypothalamus (released in both men and women).
What 2 hormones related to reproduction are released from the pituitary gland?
FSH (follicle stimulating hormone)
Luteinizing hormone (LH)
Both are found in men and women.
Estrogen and progesterone are released from what organs?
Ovaries and placenta and small amounts from the adrenal glands, and adipocytes.
Testosterone is released from what 2 organs?
Testes primarily and adrenal glands.
What mineral has the most impact on the female reproductive system?
Iron
What are the 2 steps of the follicular phase?
1) hypothalamus releases GnRH and stimulates FSH and LH release. FSH and LH stimulate follicular development and egg maturation.
2) At the end of the phase there is a surge in LH which releases the egg. There is also a surge in estrogen which stimulates growth of uterine lining.
What are the 4 steps of the luteal phase?
1) FSH and LH decline
2) egg begins to grow and forms the corpus luteum after ovulation.
3) Ovulation occurs and corpus luteum is implanted in the endometrium.
3) Follicle releases progesterone mainly and some estrogen which maintains the endometrium.
4) Without fertilization the corpus luteum is lost and progesterone and estrogen decrease and endometrium is lost.
In the male reproductive system, which hormones affect the release of testosterone from the testes?
GnRH fluctuate and LH and FSH are released which stimulate the release of testosterone.
Which hormones stimulate the maturation of sperm and how long does it take?
Testosterone and other androgens.
70 -80 days
Where is mature sperm stored?
epididymis
What is hypothalamic amenorrhea?
When menstruation stops due to a problem involving the hypothalamus. Occurs in undernourished women and the hypothalamus no longer responds to low amounts of hormones.
How does undernourishment (negative energy balance, wieght loss, low body fat, or intense physical activity) effect male fertility?
Impaired number of sperm, viability and motility and a decreased sex drive. Is related to low amounts of testosterone.
Which antioxidants protect the ovum/corpus luteum, and sperm from reactive oxygen molecules?
Which ones in specific for men?
Vit. C, vit. E, beta-carotene, and selenium.
zinc in testosterone synthesis and sperm maturation
What are the classifications of BMI and how do they correlate with infertility?
underweight = <18.5 = increased risk normal = 18.5 - 24.9 = least overweight = 25 - 29.9 = increased obese I = 30 -34.9 = high obese II = 35 - 39.9 = very high obese III = >40 = extremely high
With an increase in obesity there is also an increase in these hormones that cause menstrual irregularities. What are these hormones?
Androgens (testosterone)
Leptin from adipocytes
Estrogen is continuous and inhibits GnRH
The risk of developing PCOS increases with obesity. What are some of the side effects?
Hyperandrogenism, impaired ovarian folliculagenesis due to hyperinsulinemia.
Is associated with android fat distribution.
Ovaries become hardened and disrupts the release of the egg. If egg is released it is still possible the egg is still immature.
The development of PCOS increases the risk of developing dyslipidemia, CVD, and diabetes. Both are associated with ___ and ____ but it is unclear which comes first.
Insulin resistance and hyperandrogenemia.
How does obesity effect the male reproductive system and why?
decreases the sperm count and motility, as well as increases the risk of erectile dysfunction.
Testosterone is decreased, leptin and estrogen is increased, and thought to be because of a higher scrotal temperature.
What are 3 other factors associated with infertility in women?
Vegetarian/ vegan - primarily due to malnutrition
Iron status - high iron can be related to oxidative stress.
Alcohol - very high intake
What are 3 other factors associated with infertility in males?
Vitamin D, alcohol (affects sperm production), heavy metal and chemicals.
What are the 3 critical periods of fetal development?
Hyperplasia - increased cell multiplication, the building of new organs and tissues, damage in this time is irreversible.
Hyperplasia and hypertrophy - cell multiplication and growth
Hypertrophy - protein accumulation, cell growth. Usually, the damage is reversible (ie. low birth weight baby).
In fetal development, when is the main embryonic period, and the fetal period?
0 -8 weeks
9 - 38 weeks
In what weeks of pregnancy is there the most risk for NTD’s?
0 - 16 weeks
In what weeks of pregnancy is there the most risk for low-set malformed ears and deafness?
4.5 - about 30
In what weeks of pregnancy is there the most risk for development of microphthalmia, cataracts, and glaucoma?
4.5 - 7.5 weeks
Why is nutritional status prior to pregnancy important?
some critical periods of fetal development occur before women know they are pregnant. If the nutrients are not available in this critical time then the effects are irreversible. Iron is almost impossible to catch up with bc needs are so high.
Teratogens (substances that can harm the eggs) need time to clear the system.
In what weeks of pregnancy is it critical for development of the heart?
3.5 - 6.5 weeks
What is the cause of a neural tube defect and when does is occur?
Failure of closure of the neural tube during week 3 or 4. Various degrees of severity.
What is the most common congenital anomaly in the US and Canada?
NTD’s - many suspected to be miscarried.
What is anencephaly?
A NTD that is an incomplete brain formation, and absence of forebrain and skull. Second most common NTD.
What is encephala?
Very rare NTD that is a protrusion of brain and membranes trough the skull.
What is spina bifida?
A NTD that is an incomplete spinal cord formation. A “lump” may form on the spinal column and will effect body function.
Control of muscles below the defect affect the lower limbs and bladder. If defect is high on spinal cord then death may occur.
What is the evidence that suggests the link of folate and NTD’s (3)?
- Women who give birth to babies with NTD’s have lower serum folate and dietary intake of folate.
- Epidemiological studies show that regions with higher dietary folate intake have lower rates of NTD’s.
- Women who take a folate supplement before and during pregnancy have a lower risk of having a baby with NTD’s.
What are the 3 forms of the B vitamin folate?
Folate - the biological form and has many glutamates
Folic Acid - the synthetic form and can be converted to folate. Is a monoglutamate which increases the absorption rate.
Tetrahydrofolate - the bioactive form
What is the likely mechanism that connects folate and NTD’s?
Methylation
What is methyleneTHF reductase (MTHFR)?
It is the rate limiting enzyme in the methyl cycle and is encoded by the MTHFR gene.
Explain the variant MTHFR gene associated with increases plasma homocysteine and risk of NTD.
The MTHFR CC normal genotype produces the variant with the highest enzymatic activity which results in a decrease in 5, 10 - methyleneTHF and 10-formyl THF and then higher 5-methylTHF available for adequate methylation (adequate turnover of methionine and homocysteine).
CT (heterozygous) produces slight increased risk in NTD’s.
TT variant genotype has the lowest MTHFR activity which leads to a higher increased risk of NTD’s.
Low 5-methyl THF and high 10-formyl THF, and 5,10-methylene THF means increase/decrease in methylation and an increase/decrease in DNA synthesis?
Decreased methylation and increased DNA synthesis (TT variant). A severe risk for NTD’s.
Lowest MTHFR activity = build up of homocystein, methionine in blood. SAM activity is not dysregulated and has overexpression of DNA synthesis, protein, and lipid function.
High 5-methyl THF and low 10-formyl, and 5,10-methylene THF means and increase/decrease in methylation and and increase/decrease in DNA synthesis?
Increased methylation and decreased DNA synthesis (CC normal gene). Least risk for NTD’s. Highest MTHFR activity.
What is folate’s role in the increased risk of NTD’s?
If dietary folate prior and during pregnancy is inadequate, and if there is a genetic mutation of folate metabolism there is an increased risk of NTD’s.
What are the dietary folate equivalents?
1 DFE
=1 microgram food folate
=0.6 microgram synthetic folic acid with food
=0.5 microgram synthetic folic acid from supplement on empty stomach
What is the RDA and the UL for folate?
RDA adult females = 400 ug/day
RDA pregnancy = 600 ug/day
UL (synthetic folic acid only) = 1000 ug/day
What are naturally occurring folate found in foods?
Vegetables = peas, beans, asparagus, dark leafy greens
Fruits = oranges, orange juice, pineapple juice
Fortified Foods = bread and grain products (150 ug folic acid/100g flour) (200 ug folic acid/100g pasta)
What are teratogens and give examples?
Substances that can produce or increase the incidence of an abnormality in embryonic of fetal development. Can be toxic or harmful to the fetus.
examples. drugs (alcohol), chemicals, infections, radiation, vitamin A, lead, mercury.
Vitamin A toxicity is not normally from food but results from what (x3)?
mega dose supplements, retinoid drugs (acne medication), or frequent liver consumption.
What do retinoid drugs like isotretinoin (accutane) do?
Is a teratogen - harm the fetus
Vitamin A toxicity
There is an increased risk of spontaneous abortion
- Birth defects: craniofacial defects, cleft palate, cardiovascular and CNS abnormalities
- neurophysoiological impairment later in life (improperly formed arms and legs).
What is the female RDA and UL for vitamin A?
Exceeding the UL during pregnancy with megadose supplements can cause what? What are the recommendations when taking retinoid drugs?
RDA: 700 ug/day
UL: 3000ug/day (preformed retinols only)
Megadose supplements can cause an increased rate of birth defects.
Recommend more than one form of birth control while taking retinoid drugs and stop use at least 6 months before pregnancy.
Methyl mercury is a teratogen. What is the main food source? What does a diet high in mercury before and during pregnancy do to a fetus?
Contaminated fish CNS defects (includes cerebral atrophy), seizures, mental impairment, blindness.
What fish have the highest levels of mercury?
tuna, shark, marlin, orange roughy, escolar, canned albacorer tuna
What is the recommended fish intake for pregnant women?
at least 150 g (about 2 servings in of M & Alt. in Canada food guide) of cooked, low mercury fish each week
Alcohol is a teratogen. What does it do during pregnancy to the fetus?
Crosses the placenta and fetal liver cannot metabolize the alcohol.
Affects the CNS mostly. Heavy alcohol intake increases risk of miscarriage, stillbirth, and infant mortality.
What is thought to be the most common cause of impaired mental functioning?
Alcohol consumption
What is FAS and what are the symptoms?
Fetal Alcohol Syndrome - growth impairment, neurological abnormalities, facial characteristics. Developmental delays, behavioural and learning disabilities. Facial characteristics are abnormal. Upper lip groove is less distinct meaning that something came in the way of development during that period of pregnancy. Symptoms vary depending on when alcohol was consumed and type of alcohol consumed.
What is FAE?
Fetal Alcohol Exposure - have some of the symptoms of FAS. Mostly behavioural issues
What is the recommendation for alcohol during pregnancy?
It is unknown is there is a safe level and varies between individuals so alcohol should be completely avoided during pregnancy.
During the embryonic phase, what are some of the physical developments that occur?
Brain and central nervous system, heart, eyes, arms and legs, muscle development, facial features, and sexual organs at the end of the period.
