Contraception Flashcards
What are the Canadian rates of birth in 2023?
10.1 births per 1000
-SK: 11.9 births per 1000 (2022)
What is the average maternal age at first birth?
~30 years
What is the percentage of pregnancies that are unplanned?
40-60%
->180,700 per year
-~50% of unintended pregnancies end in abortion
-approximately 1/3 of individuals have had at least one induced abortion
What are the 5 hormones involved in the menstrual cycle?
GnRH (gonadotropin releasing hormone)
FSH (follicle stimulating hormone)
estrogen (predominantly estradiol)
LH (luteinizing hormone)
progesterone
What is the role of GnRH in the menstrual cycle?
stimulates pituitary to release FSH and LH
What is the role of FSH in the menstrual cycle?
stimulates maturation of follicles in ovaries
What is the role of estrogen in the menstrual cycle?
stimulates thickening of endometrium (uterine lining)
suppresses FSH (negative feedback)
signals LH
What is the role of LH in the menstrual cycle?
triggers ovulation
What is the role of progesterone in the menstrual cycle?
produced by the corpus luteum (mass of cells resulting from the ruptured follicle when the ovum is released)
makes the endometrium favourable for implantation
signals the hypothalamus and pituitary to stop FSH and LH production (negative feedback)
What is the average cycle length?
average is 28 days (range 21-40 days)
What is day 1 of the cycle?
first day of period (menses)
Describe the follicular phase.
day 1:
-first day of period
days 1-4:
-increases in FSH (follicle grows/develops)
days 5-7:
-one follicle becomes dominant
-starts producing estrogen (estradiol)
–>stops menstrual flow
–>stimulates thickening of endometrial lining
–>increased production of thin, watery cervical mucus
What does consistently high estrogen levels cause?
stimulates the pituitary to release a mid-cycle surge of LH
LH=follicle maturation and triggers ovulation
When does ovulation occur?
~28-32 hours after LH surge
typically around day 14 of a regular cycle
Describe the luteal phase.
14 days long
released ovum travels through fallopian tubes to the uterus
if no implantation:
-corpus luteum deteriorates and stops producing progesterone
if implantation occurs:
-corpus luteum continues to produce progesterone but that function is ultimately taken over by the placenta
What is the corpus luteum?
“left over” follicle
produces androgens, estrogen, and progesterone
progesterone provides negative feedback to stop FSH and LH production
maintains endometrial lining
Describe the transition back from the luteal phase to the follicular phase.
as progesterone levels decrease
-endometrial lining is shed (menstruation)
-low progesterone and estrogen levels stimulate release of GnRH
What are the four methods of contraception?
hormonal
barrier
permanent
natural family planning
What are the two components of hormonal contraceptives?
estrogen
progestins
What are the two forms of estrogen that can be in hormonal contraceptives?
ethinyl estradiol (EE)
-synthetic form of estradiol
-most common form
estetrol
-plant source
What are progestins structurally similar to?
testosterone
-androgenic effects (acne, oily skin, hirsutism)
Which progestins are anti-androgenic?
cyproterone acetate (Diane-35)
drosperinone
What is the MOA of hormonal contraceptives?
estrogen and progestin provide negative feedback which inhibits ovulation
estrogen:
-suppresses release of FSH
progestin:
-suppresses release of LH and FSH
-thickens cervical mucus (impedes sperm transport)
-changes endometrial lining (not hospitable for implantation)
What are the routes of administration for hormonal contraception?
oral (the Pill)
injectable
transdermal
intravaginal
intrauterine (hormonal and non-hormonal options)
implantable
List the routes of administration available for the following categories of hormonal contraception.
-combined
-progestin only
-long acting reversible contraception (LARC)
combined:
-pill
-patch
-ring
progestin-only:
-pill
-injection
long-acting reversible contraception (LARC)
-IUS/IUD
-implant
True or false: the types/doses of estrogen and progestin are identical in between products
false
it varies
Describe cyclic dosing of COC.
COC originally developed to mimic 28-day cycle
21 days of API + 7 days placebo
24 days of API + 4 days HFI
24 days of API + 2 days EE + 2 days HFI
monophasic, biphasic, or triphasic
What are the 3 phasic formulations for COC dosing?
monophasic: fixed levels of EE and progestin
biphasic: fixed EE levels; increased progestin in 2nd phase
triphasic: fixed or variable EE levels; increased progestin in all 3 phases
different colours of pills for different strengths
What is the idea of multiphasic products?
attempt to imitate the normal menstrual cycle-higher proportion of progestin to EE in second half of cycle
no difference in efficacy, bleeding patterns, or adverse effects
What is extended dosing of COC?
> 1 “cycle” of active pills then HFI
84 days of API + 7 days EE (10mcg) or HFI
What is continuous dosing of COC?
can use any product (<50mcg EE) for continuous dosing (oral, transdermal, vaginal)
-even multiphasic products
True or false: there is no difference in efficacy or short-term adverse effects between cyclic and extended/continuous dosing
true
When is it most effective to start the pill?
most effective if started on day 1 (first day of period) and taken daily at the same time daily
What should be done if someone did not start the pill on day 1?
use back-up birth control method for first 7 days
takes 7 days of continuous pill to use to suppress ovulation
Describe the efficacy of COC.
perfect use: <0.3% failure rate
-one pill OD exactly 24hrs apart
typical use: 3-8% failure rate
-forgetting to take pill or taking it late (>24hrs apart)
-starting pack late
What are the adverse effects that are common in first 3 months of starting the pill?
breakthrough bleeding:
-check adherence
-if lasts >6months look for other causes (STIs)
breast tenderness:
-if lasts longer than first 3 months, look for other causes
nausea
What are some possible remedies for breakthrough bleeding, breast tenderness, and nausea from COC?
BTB:
-change to pill with higher estrogen/progestin (depending when BTB occurs in cycle)
breast tenderness:
-change to pill with less estrogen
nausea:
-take HS or with food
-change to pill with less estrogen
What are other adverse effects of COC? (other than the ones that are common in the first 3 months)
weight gain
-some notice increased appetite in first month, but overall little or minimal weight gain
headache or migraine
-can be hormone-related (can either increase or decrease with use)
mood changes-depression?
-some evidence for an association
acne
-can worsen initially but usually improves with long-term use
-continued problem? change to pill with less androgenic activity
What are the potential benefits of COC?
simple and effective birth control
improves menstrual symptoms and regularity
-reduces dysmenorrhea and ovulation pain
-reduces PMS symptoms
decreases incidence of:
-endometriosis
-endometrial cancers
-ovarian cancer
-ovarian cysts
-osteoporosis (increased bone density)
-acne and hirsutism
What are the risks of COC?
contraceptive failure:
-especially if missed pills with <20mcg estrogen
VTE:
-risk is 2-3x higher than in non-users
-risk increases with age, smoking, higher estrogen doses
-controversy whether drospirenone increases risk
MI and stroke (arterial thrombosis):
-increased risk associated with estrogen >50mcg/d, age >35, smoking, HTN, CVD risk factors
breast cancer:
-suggested there is an increased risk of 1.3x
-risk may return to baseline within 10yrs of DC
cervical cancer:
-suggested increase risk of 1.5x with >5yrs use
What are the early danger signs of COC?
ACHES
-abdominal pain (severe)
-chest pain (severe) or SOB
-headaches (severe)
-eye problems (blurring, flashing, vision loss)
-severe leg pain (calf or thigh)
What are the 3 main types of potential drug interactions for COC?
drugs that reduce the enterohepatic circulation of oral contraceptives
drugs that induce the metabolism of oral contraceptives
drugs that have their metabolism altered by oral contraceptives
What are the drugs that reduce enterohepatic circulation of oral contraceptives?
antibiotics: ???s
-increased intestinal transport (diarrhea)
-decreased enterohepatic reabsorption of estrogen
-penicillins, cotrimoxazole, nitrofurantoin, metronidazole
What is the management of the antibiotic-COC drug interaction?
no interactions: no restrictions to use
except rifampin
What are the drugs that induce metabolism of COC?
CYP450 3A4 inducers
-anticonvulsants (carbamazepine, phenytoin)
-rifampin
-herbals (STJ wort)
What is the management of the interaction between COC and drugs that induce its metabolism?
use product with higher estrogen levels (>30ug EE)
use extended dosing (skip HFIs)
use alternative to interacting drug or other method of birth control
Which drugs have their metabolism altered by oral contraceptives?
lamotrigine
-significantly reduced levels by induction of lamotrigine glucuronidation
What is the management of the oral contraceptive-lamotrigine interaction?
use alternative to interacting drug or other method of birth control
What are the contraindications to COC?
thromboembolic disease (current or past VTE)
HTN (>160/100mmHg)
ischemic heart disease/stroke
known or suspected breast cancer
migraine with aura
severe/active liver disease
post-partum (wait 3-6wks post-partum bc increased risk of VTE)
smokers (>15cigs/d) over 35 years old
What is the dosing of the transdermal patch (Evra)?
0.6mg EE + 6mg norelgestromin
-average daily release of 35ug EE + 200ug norelgestromin
Describe the efficacy of the transdermal patch.
perfect use:
-failure rate=0.3-0.7%
typical use:
-failure use=8%
Describe administration options of the transdermal patch.
apply patch on day 1 (no back-up method needed)
apply first Sunday (back-up method x 7d)
How long should one transdermal patch be left on?
1 patch applied weekly x 3 weeks
then no patch for 1 week (HFI)
Where can the transdermal patch be applied?
upper arm
buttocks
lower abdomen
upper torso
good adhesive, <2% fall off
What are the adverse effects of the transdermal patch?
similar to oral contraceptives
local skin irritation (20%)
can have increased spotting in first 2 cycles
When would transdermal patches be less effective and have increased risk of clots?
weighing >90kg
What are the drug interactions for the transdermal patch?
similar to COC
What is the Nuvaring?
flexible, non-latex vaginal ring
EE 15ug + 120ug etonorgestrel released daily
Describe the efficacy of intravaginal contraception.
perfect use:
-failure rate=0.3-0.8%
typical use:
-failure rate=8%
Describe administration of the Nuvaring.
insert (anywhere in the vagina) between days 1-5
-backup birth control for 7 days if not day 1
leave in for 3 weeks, remove for 1 week (HFI)
When is expulsion a concern for the Nuvaring?
if out for >3hrs
expulsion rate is ~4%
What is something to always ask if someone missed a dose of a contraceptive?
unprotected sex in last 5 days?