Contraception- King Flashcards
What does GnRH do in the menstrual cycle?
What do FSH and LH in the menstrual cycle?
GnRH is pulsed every 60-90 minutes to cause release of FSH and LH
FSH stimulates the granulosa cells of the follicle to produce estrogen; LH promotes theca cells to produce androgens
What determines which follicle becomes dominant?
What happens to hormone regulation in the follicle when estradiol levels are high?
The follicle which expresses the most FSH receptors and produces the most estradiol ends up becoming the dominant receptor.
LH becomes a positive feedback system and LH levels increase over FSH levels.
What happens because of the LH surge?
What happens because of progesterone?
LH surge
- Meiosis of the oocyte in the dominant follicle
- Granulosa cells become corpus luteum
- Follicle ruptures about 10-12 hours post surge
Progesterone
- Suppresses additional follicle development
- Increased endometrium bulk
How long is the oocyte viable after ovulation?
How long is sperm viable?
12-24 hours
up to 5 days
What are the three strategies surrounding contraception?
What methods of birth control fall under each strategy?
- Prevent Ovulation
- Combined hormonal implants, injections, pills
- Prevent Fertilization
- Abstinence
- Fertility Awareness
- IUD
- Progestin only pill
- Barrier
- Sterilization
- Spermicide
- Prevent Implantation
- possibly secondary IUD mechanism
How do combined hormonal methods of birth control work?
What is the role of each hormone?
- Prevents ovulation
- Thickens cervical mucus
Progestin- dampens GnRH pulses, inhibits LH surge
Estrogen- suppreses FSH selection of a dominant follicle
Which two hormones are used in current combined contraceptive pills?
What benefits are there from the formulation?
Ethinyl estradiol and Progesterone
Drospirenone prevents the bloating that usualy accompanies the high estrogen in the pills.
What are some contraindications for combined hormonal contraceptives?
- Increased levels of factors 2,7,8,10, and fibrinogen
- Decreased protein S, anti-thrombin, and TF-inhibitor
- Postpartum or pregnant
- Hx of MI, CAD, or stroke
- Cigarette smokers >35 yo
- Complicated diabetes w/ vascular disease
- BP >160/100
- Migraines w/ aura
- Liver disease
- Hx of breast, endometrial cancer
What is the mechanism of progestin only pills?
What is their dosing?
Thickens cervical mucus to prevent fertilization and slow ovum transport. Thins endometrium to prevent implantation.
Pill must be taken at the same hour every day; this is especially important.
What is DMPA (aka depovera)?
What are some unique side effects of this drug?
IM or SQ injection given every 3 months
- 7-10 months before fertility returns after stopping
- Reversible decrease in bone density
- unaffected by hepatic enzymes
- Decreases sickle cell crises, seizures
What hepatic enzyme is responsible for metabolizing hormonal birth control?
What medications should be watched for interactions with hormonal birth control?
Hepatic cytochrome p450 3A4
- Rifampin
- Griseofulvin
- St. John’s Wort
- Modafinil
- HIV protease inhibitors
- Phenytoin
- Carbamazepine
- Phenobarbital
What two varieties of IUDs are available?
What are their mechanisms of actions?
Hormonal IUD- thickens cervical mucus and creates inflammatory environment which blocks sperm
Copper IUD- Copper ions blow holes in sperm and oocytes (also prevents implantation: effective as emergency contraception)
How effective are IUDs at preventing pregnancy?
What are some contraindications for IUDs?
Slight less effective than sterilization (1.4% vs 1.3%)
- Pregnancy
- Pelvic Inflammatory Disease
- Sepsis or Infection
- Malignancies of genital tract
- Wilson’s disease (copper IUD)
What are barrier methods of birth control?
How effective are they?
- Male Condom
- Female Condom
- Cervical Cap
- Diaphragm
- Sponges
Much less effective than hormonal methods; even male condoms have a first year failure rate of 18%.
What are some methods of fertility awareness?
Standard days method- track your cycle and guess
Cervical mucus method- check to see if mucus is clear, stretchy
Sympto-thermal method- basal temp rises during ovulation, used with mucus checking
Sympto-hormonal method- urine LH spikes are tracked, used with mucus checking
