Preconception Flashcards
Fertility
the actual production of children
Fecundity
the biological capacity to bear children
Infertility
lack of conception after 1 year of unprotected intercourse
Subfertility
reduced level of fertility characterized by unusually long time for conception such as having multiple miscarriages, sperm abnormalities, or infrequent ovulation
Gonadatropin Releasing Hormone (GnRH)
Stimulates pituitary to release FSH and LH
Follicle Stimulating Hormone (FSH)
Stimulates maturation of ovum & sperm
Luteinizing Hormone (LH)
Stimulates secretion of estrogen, progesterone & testosterone
Estrogen
Stimulates release of GnRH in follicular phase
Stimulates vascularity & storage of glycogen & other nutrients within uterus
Progesterone
Prepares uterus for fertilized ovum
Increases vascularity of endometrium
Stimulates cell division of fertilized ova
Follicular Phase
First half of cycle
Follicle growth & maturation
Main hormones: GnRH, FSH, estrogen, & progesterone
Luteal Phase
Second half of cycle, after ovulation
Formation of corpus luteum (hormone secreting cyst)
Decrease in estrogen & progesterone stimulate menstrual flow
Prostaglandins & cramps
Testosterone and androgens
stimulate the maturation and release of sperm from the testes (spermatogenesis)
Physiological factors contributing to normal fertility
Normal menstrual cycle (Production of ova)
Sperm maturation, production and storage
Sperm motility
Nutrition related disruptors in fertility
Under nutrition Weight loss Obesity High exercise levels Intake of specific foods & food components
Undernutrition
Chronic
- Small impact on fertility and fecundity
- Higher likelihood of small frail infants and infant death
Acute
- Results in dramatic decline in fertility but is recovered with recovered food intake
- Reduces reproductive capacity by modifying hormonal signals that regulate -ovulation and menstrual cycles in females
- Also impairs sperm maturation in male
Adipokines
Cell signaling proteins secreted by adipose tissue important to many metabolic processes (estrogen, androgen, leptin specifically for preconception)
Body fat and fertility
Excessive and inadequate body fat levels will alter the hormone balance and affect the reproductive cycle
Adipose tissue converts androgens to estrogen by aromatization
Body fat is thus a significant extragonadal source of estrogen
Obese men have significantly lower circulating levels of testosterone
Adiposity influences the direction of estrogen metabolism to more potent or less potent forms
Low body fat can lead to…
Delayed onset of menstruation
Amenorrhea
Lowered libido
Reduced sperm production
High body fat can lead to…
Increased leptin and insulin levels and a preferential increase in LH, but not FSH, levels.
High insulin levels increases ovarian testosterone production/action.
The net effect of these changes is to stimulate the partial development of follicles that secrete supranormal levels of testosterone, but which rarely ovulate (hence low progesterone).
Exercise and fertility
Exercise is associated with positive fertility outcomes
Mechanism: Exercise increases insulin sensitivity, which is related to ovarian function
Moderate-intensity exercise is more beneficial that high-intensity exercise
Oxidative stress and fertility
Free radicals can harm:
- Sperm motility and ability to fuse with egg
- DNA within the sperm cell
- Egg and follicular development
- Implantation of egg in uterine wall
Free radicals
reactive oxygen species formed during regular metabolic processes containing extra valence electrons and therefore making them more prone to react with other molecules and cause damage (oxidative stress)
Antioxidants
neutralize free radicals by donating extra valence electrons
Caffeine and fertility
High intakes are linked to reduced fertility (definition of high intake is not clear <200-300mg/day)
Adenosine receptor antagonist that may influence fertility in women but not men
Alcohol and fertility
Alcohol intake alters the hormonal milieu
- Decreases estrogen and testosterone levels
- Disrupts menstrual cycle
- Disrupts testicular function
How much? Not entirely clear.
1-5 drinks/week = ~40% decreased chance of conception
Over 10 drinks/week = ~66% decreased chance of conception
Folic Acid
Neural Tube Defects (NTD) such as Spina Bifida and Anencephaly are a very common birth defect due to the neural tube developing and closing at 4 weeks
Folic acid functions as a coenzyme during the synthesis of nucleic acids and therefore is required for cell division and formation of the neural tube
All processed grain products were mandated to be fortified with folate beginning in 1998
Iron
Many women have low iron stores due to menstruation or low iron intakes
Improvements in iron status associated with improved fecundity.
Possible role in oocyte development?
Calcium
Associations between dairy intake and fecundability were generally small and inconsistent across cohorts, maintain RDA
Vitamin A
Retinoic acid is used in dermatology to cure acne and psoriasis
Should not be prescribed during pregnancy or in women planning to become pregnant
Teratogenicity
the ability to cause defects in a developing fetus
Vitamin D
Supplementation associated with
- Increased endometrial thickness
- Improved serum lipids
- Decreased risk of endometriosis
Important to correct insufficiency and deficiency
Conditions impacting conception
Premenstrual syndrome (PMS)
Obesity Underweight Female athletic triad Eating disorders Diabetes Polycystic ovary syndrome Phenylketonuria, Celiac disease
