Exam 2 - Emergency Contraception and Medication Abortion Flashcards
What is emergency contraception?
drug or device used to prevent pregnancy after unprotected sexual intercourse, not intended to be used as an ongoing method of contraception
Why is EC controversial?
- form of abortion?
- exact mechanism of action has not been communicated to the public
What was the original “morning after pill”?
combined progestogen and estrogen, called the Yuzpe regimen (was associated with nausea and vomiting)
What are the new “morning after pills” and why are they better options?
progestogen only, specifically levonorgestrel (LNG-EC)
Plan B: two 0.75 mg doses 12 hours apart
Plan B one-step: one 1.5 mg dose
both are better tolerated because they don’t contain estrogen
According to directions, EC can be taken up to —- after unprotected sex
3 days, 72 hours
Describe the effectiveness of Plan B (including timing)
87% effective when used as directed (7/8 did not become pregnant)
61-95% effective
24 hours: 95% effective
48-72 hours: 61%
What were the assumptions made by most prior studies about timing of LNG-EC, ovulation, and unprotected intercourse?
females accurately report first day of menstrual cycle, females always ovulate on day 14, ovulation occurs exactly 14 days before menses (luteal phase is always 14 days)
What was the purpose of the Noe 2011 study?
determining the mechanism of LNG-EC based on its effectiveness when administered at times relative to unprotected sexual intercourse and ovulation
How can blood tests and vaginal ultrasound be used to determine day of ovulation?
blood tests:
LH, estradiol, and progesterone are high and low at different points in the cycle
ultrasound:
size of follicles (average rupture at 20 mm), endometrial appearance
What is the probability of conception at different points in the menstrual cycle?
conception only occurred during a 6 day period, ending on the day of ovulation
greatest (about 30%) on day -2 and -1
How is conception rate data collected and analyzed?
females wanting to become pregnant underwent urine testing to determine their ovulation dates, they reported when they had sexual intercourse, and pregnancies were tracked
How did the Noe 2011 study use conception data to estimate the number of expected pregnancies?
number of patients that had intercourse that day of their cycle * conception rate for that day of the cycle = expected pregnancies for the patients that had intercourse on that day
do this for each day (-6 through 0) and add together to get expected pregnancies for all patients combined
How did the Noe 2011 study use the observed number of pregnancies to conclude things about the mechanism of LNG-EC action?
for LNG-EC administration pre-ovulation:
16 expected, 0 observed
for LNG-EC administration post-ovulation:
8.7 expected, 8 observed
role in pre-fertilization events, no role in post-fertilization events
What are potential mechanisms of action of LNG-EC?
- prevent follicle maturation or ovulation if taken at least one day before ovulation by suppressing LH, FSH, or LH surge
- single dose of LNG only affects cervical mucous and sperm motility for 24 hours
How can IUDs be used as EC?
can be inserted up to 5 days after unprotected sexual intercourse
in mid to late follicular: immobilize sperm or prevent migration to the oviduct for fertilization
in luteal phase:
creates inflammatory reaction in endometrium and copper is embryotoxic
