12. Contraception and infertility Flashcards
What is contraception?
Any method to prevent pregnancy
What are 3 mechanisms that contraception
- Blocking transport of sperm to avoid fertilisation of oocyte
- Disrupting the HPG axis to interfere with ovulation
- Inhibiting implantation of the conceptus into endometrium
What are the 6 broad categories of contraceptions?
- Natural
- Barrier
- Hormonal Control
- Prevention of implantation
- Sterilisation
- Emergency contraception
What is the only category of contraceptions that protects against STIs?
Barrier
What are 4 types of natural contraceptions?
- abstinence
- withdrawal
- fertility awareness methods
- Lactational amenorrhoea method
What are the advantages and disadvantages of abstinence?
Advantages: 100% effective
Disadvantages:
• Not an option for most.
• Unprepared if/when sexually active
what is withdrawal?
Aka. Coitus Interruptus
= Withdrawal before ejaculation
What are the advantages and disadvantages of withdrawal?
Advantages: no devices or hormones Disadvantages: • Unreliable • Some sperm in pre-ejaculate • No STI protection
What is the fertility awareness method?
Use of fertility indicators to identify fertile and infertile points of the menstrual cycle
What fertility indicators can be used in fertility awareness method?
- Cervical secretions + Changes in Cervix
- Basal body temperatures
- Length of menstrual cycle
What are the advantages and disadvantages of the fertility awareness method?
Advantages
• No hormones/contraindications
Disadvantages
• Time-consuming, Unreliable, no STI protection
• Not suitable for all - not everyone has regular periods
What is lactational amenorrhoea method and how does it work?
Lactation delays the onset of ovulation, as the hypothalamus is ‘switched off’ because the suckling response lowers the release of GnRH to high levels of prolactin
How long after giving birth does lactational amenorrhoea methodq work?
Can be used effective for up to 6 months postnatally provided:
• Exclusive breastfeeding
• Complete amenorrhoea
What are the advantages and disadvantages of lactational amenorrhoea method?
Advantages: No hormonal/contraindications
Disadvantages: Unreliable after 6 months, no STI protection, Not suitable for all
What are the different types of barrier contraceptives and how do they work?
Provide physical +/– chemical barrier to sperm entering the cervix e.g.
• Male/Female condoms ‘Femidom®’
• Diaphragms/Cervical Caps
• Spermicides
What are the advantages of barrier contraceptives?
- Reliable - 98% effective (if used correctly)
- Protection from STIs
- Male condom is widely available
What are the disadvantages of barrier contraceptives?
- Disrupts intercourse, Risk of Dislodging
* Allergy/sensitivity to latex
How does hormonal control act as a contraceptive?
o interrupt HPG axis, and prevent ovulation. May have effects on endometrial lining.
Short-Acting or Long-Acting Reversible Contraception (LARC)
What are the different types of hormonal contraceptives?
- Combined Oestrogen and Progestogen – COCP, Patch, Ring
- Progestogen-only Pill (POP)
- LARC – Progestogen Depot and Implant
Describe the action of progesterone in high and low doese
- HIGH Levels of Progesterone enhances the negative feedback of oestrogen, hence:
- Pre-ovulation – Reduces FSH and LH secretion
- Inhibits positive feedback of high oestrogen → × LH surge → × ovulation
- LOWER Levels of Progesterone
- Does NOT inhibit LH surge → can still ovulate
- Will thicken cervical mucus
What is the COCP?
Pill containing combination of synthetic oestrogen and progestogen
How often should the COCP be taken?
Usually taken for 21 days with a 7 day break OR 21 days + 7 placebo pills
What are the actions of the COCP?
Principal action:
•Prevents ovulation - by negative feedback of oestrogen and progesterone on HPG axis reducing H surge
Secondary action:
•Reduces endometrial receptivity to inhibit implantation
•Thickens cervical mucus to inhibit penetration of sperm
What are the advantages of COCP?
• Reliable (if used correctly) up to 99% • Can relieve menstrual disorders • reduced risk of ovarian and endometrial cancer • reduced Acne severity in some
What are the disadvantages of COCP?
- User dependant
- No STI protection
- Medication interaction
- Contraindications – raised BMI, migraine + aura, breast cancer
- Side effects – menstrual irregularities, breast tenderness, mood disturbance
- reduced risk of CV disease, Stroke, VTE, Breast cancer, cervical cancer
What dose does the progesterone only pill contain?
low dies progestogen
What are the actions of POP
Main action: Thicken cervical mucus.
Other action: reduced cilia activity in fallopian tubes
Ovulation NOT prevented.
How often should the POP be taken?
Taken daily with no breaks.
What are the advantages of POP?
- Reliable (if used correctly) up to 99%
* Can be used if COCP contraindicated