Lec5 Fertility Control Flashcards
What is progesterone’s role in pregnancy?
Progesterone supports potential pregnancy
What happens when progesterone drops?
Labour is induced
How is temporary, reversible infertility brought about?
Need to stop/prevent ovulation
Suppression of LH surge - to prevent ovulation by giving progesterone - this works by negative feedback
How do female contraceptives work?
Prevent ovulation
Thicken cervical mucus
Hostile endometrium
What effect does progesterone have on the LH surge?
Prevents the LH surge - so ovulation cannot happen
What effect does progesterone have on cervical mucus?
Thickens cervical mucus so that sperm cannot get in
When are progestogens given?
They are given at the start of the menstrual cycle so that the endometrium stays thin - it’s a hostile environment and will not support a fertilised ovum
What does giving oestrogen do?
Suppresses FSH - so the ovum doesn’t develop
What is the combined oral contraceptive pill?
It is oestrogen and progesterone given together
What effect does the combined oral contraceptive pill have?
It reliably suppresses ovulation, thickens cervical mucus and thins endometrium to make it hostile
What is the pregnancy rate of progesterone only pill?
5% out of 100 women having regular unprotected sex for a year
What is the pregnancy rate of combined contraceptive oral pill?
3 in 10,000 women in a year
In Brighton why is it 5 pregnancies per 100 in a year?
Because they don’t take it properly
How many days do you take the tablets for and how many non tablet days are there with the oral combined contraceptive pill?
21 days tablets
7 days no tablet
What happens during the 7 day tablet free period?
Withdrawal bleed
What are the fears about the endometrium?
Fears that if you don’t get rid of the endometrial lining regularly, it can increase the chances of endometrial thickening and endometrial cancers
What happens if a woman has diarrhoea or vomiting?
They may not have absorbed the pill and should take an additional pill
Contraindications of the combined oral contraceptive pill?
Antibiotics wipe out the gut bacteria
Some minor evidence that taking antibiotics and taking the pill increases the chances of pregnancy
What happens when people take the pills in the wrong order - up and down rather than left to right?
Dramatically increased failure rate of the pill
What happens if you miss a pill every three days with the COCP?
Nothing really happens - won’t make much difference
What happens if you miss days at the start of the menstrual cycle?
It renders it ineffective - extends the number of drug free days and increases chances of pregnancy
If you have 9-10 drug free days, what is likely to happen?
An ovum will develop and there is a risk of ovulation
Give an example of the progesterone only contraceptive pill and describe how it works.
Levonorgestrel
Progesterone suppresses the LH surge - preventing ovulation
Thickens cervical mucus
Renders endometrium ‘hostile’
What is the standard dose of the progesterone only contraceptive pill?
350mcg 1 tablet daily
What are the adverse effects of the progesterone only pill?
Menstrual irregularity Nausea Vomiting Headache Breast discomfort Weight changes Changes in libido
How long does this pill use contraception for and how late can you be in taking it?
22 hours/day
Can be late by 12 hours in taking it but no more than that
What is the combined oral contraceptive pill and how does it work?
Combination of oestrogen - usually ethinyloestrodiol and progesterone - norethisterone
The progesterone inhibits LH surge - so prevents ovulation and thickens cervical mucus
Oestrogen inhibits FSH release and therefore development of the ovum
What is the standard dose of the COCP?
1 tablet for 21 days - oestrogen 20-35mcg ethinyloestrodiol & 500-1000mcg norethisterone
7 days drug free
What are the adverse effects of the COCP?
Nausea, vomiting, abdominal cramps, fluid retention, changes in body weight, hepatic impairment, cardiovascular changes including DVT, breast tenderness, cervical erosion
Exacerbation of migraine
Chloamsa
Mood changes
What other forms of female contraception are there?
Intrauterine
Implants
Vaginal
What other symptoms are contraceptives used to treat?
Painful periods - dysmenorrhoea
Heavy menstrual bleeding (HMB)
The progesterone thins the endometrium - so reduces bleeding and reduces pain
What are IUDs and how do they work?
Solid plastic rod inserted into the uterus
Causes a local sterile inflammatory response
No infection
A fertilised ovum can’t implant into the uterus
Why are IUDs recommendable?
Because IUDs are the most effective form of contraception
What is an IUS?
IntraUterine System - an IUD that releases low dose of progestogen - this suppresses ovulation
What are implants and how do they work?
Solid ring subdermally inserted Releases progesterone over 3 years Constant release- no drug free period Total lack of withdrawal bleed Very reliable Some women report irregular bleeding - appears that the endometrium is thin but breaks down suddenly even with the implant in place
How do vaginal contraceptives work?
Progesterone is inserted vaginally by a silicone ring - effective absorption by the vaginal mucosa
Name two drugs used for emergency contraception “morning after pill”.
Levonorgestrel
Ulipristal
How effective are these emergency contraceptives?
Levo-norgestrel - 70-80%
Ulipristal is more effective than levonorgestrel
How does ulipristal work?
It is a progesterone analogue - partial agonist
Blocks the progesterone receptor - progesterone can’t bind - endometrium collapses/ won’t support the pregnancy/implantation
Why can’t ulipristal be used long term?
Not as effective as the oral contraceptive pills
What can go wrong with ulipristal use?
If ovulation has already occurred then it is too late for it to work but ulipristal may disrupt implantation
What drug is used for induced abortion and how does it work?
Mifepristone - a progesteron antagonist
Progesterone supports pregnancy
Progesterone antagonist causes progesterone to be unable to bind- drop in progesterone - endometrium lining to collapse
Induces abortion and terminates a pregnancy
How do male contraceptives work?
By blocking sperm production
FSH causes sperm production so by blocking FSH
Why not give oestrogen/progesterone to men, seeing as it blocks LH (so blocks secretion of testosterone) and FSH (blocks sperm production)?
Because it takes 3 months to make sperm
Very slow onset of action b
But also by giving progesterone and blocking endogenous testosterone, they were losing male secondary characteristics
What is a better option to block sperm production?
Giving testosterone - blocks endogenous testosterone production but continue giving testosterone so they still have secondary male characteristics
How effective are male contraceptives?
They are just as effective as female contraceptives in clinical trials
Why haven’t male contraceptives taken off?
Because of the market
Women are the ones that get pregnant
Who would trust a man that said he was on a contraceptive to take it properly etc
Why is testosterone not given orally?
Because it would cause hepatotoxicity
What is menopause caused by?
It is a hypothalamic event - not caused by eggs running out
