Contraception

Question 1

Define Contraception

Answer 1

Prevention of pregnancy before foetal implantation.

Question 2

What is the aim of conraception?

Answer 2

• Abstinence – 100% reliable!
• Block access of sperm to egg.
• Disrupt female reproductive cycle

Question 3

Female Reproductive Cycle

Answer 3

Question 4

Female HPG Axis

Answer 4

Question 5

Hormonal Contraceptives

Answer 5

• Combined oral contraceptives
• Progesterone-only contraceptives
• ‘Morning after pill’

Question 6

Name an abortive agent

Answer 6

RU486 (mifepristone)

Question 7

The Combined Oral Contraceptives consists of which 2 hormones?

Answer 7

Oestrogen & Progesterone

Question 8

Maintaining sustained levels of Oestrogen & Progesterone mimics which reproductive event?

Answer 8

Pregnancy→HPG Axis

Question 9

Combined Oral Contraceptives mechaism of action

Answer 9

Inhibit GnRH release

Inhibit FSH & LH secretion

Inhibit follicle maturation Inhibit ovulation Inhibit Corpus luteum

Thicken cervical mucous→Modify tubule motility→Endometrial changes

Question 10

Combined Oral Contraceptives: Efficacy

Answer 10

• very low failure rate (0.05%)
• usually caused by missed doses, drug interactions
• (some antibiotics), diarrhoea & vomiting.

Question 11

Combined Oral Contraceptives: Side effects

Answer 11

• increased risk of CVD, breast cancer.
• minor effects include nausea, weight gain, depression

Question 12

Combined Oral Contraceptives: Health benefits

Answer 12

• decreased risk of ovarian & endometrial cancer.
• decreased incidence of PID & ovarian cysts.

Question 13

Progesterone Only Contraceptives

Answer 13

• Mini-pill
• Depo contraceptive injection
• Contraceptive implant

(slow release, higher dose)

All contain synthetic progestogens.

Question 14

Progesterone Only Mini-Pill

Answer 14

• Pituitary still responds to GnRH
• Inhibit FSH & LH secretion
• Can be ovulatory – depends on degree of HPG suppression
• Thicken cervical mucous→Modify tubule motility

→endometrial changes

Question 15

Depo (medroxyprogesterone acetate) Contraceptive Injections

Answer 15

• Inhibit GnRH release
• Inhibit FSH & LH secretion
• Inhibit follicle maturation→Inhibit ovulation

→Inhibit Corpus luteum

• Thicken cervical mucous→Modify tubule motility

→Endometrial changes

Question 16

Progesterone Only Contraceptives: Efficacy

Answer 16

• very low failure rate (<1%) if taken correctly.
• (mini-pill must be taken daily in very short time window).

Question 17

Progesterone Only Contraceptives: Side effects

Answer 17

• rare (acne, breast tenderness and breast enlargement,
• mood changes, headaches, nausea).
• Depo injections – can take up to 2 years to recover normal fertility.

Question 18

Morning After Pill

Answer 18

• Emergency contraception used within 72 hrs after unprotected sex.
• Progesterone only.
• Primary mechanism of action is to inhibit ovulation.
• Suppression of HPG – inhibit FSH and LH.
• Efficacy rates ~ 75-85%.

Question 19

RU486 (Mifepristone)

Answer 19

Progesterone ANTAGONIST

Licensed in the UK for termination of pregnancy NOT post-coital contraception.

Question 20

RU486 (Mifepristone) Mechanism of action depends on stage of cycle:

Answer 20

• Mid-cycle →disrupts ovulation
• Luteal phase →prevents implantation
• After implantation →causes loss of foetus

Question 21

Male Contraceptive Pill

Answer 21

Several under development with different modes of action:

• stop sperm production
• inhibit sperm motility
• inhibit testosterone production

Example: dimethandrolone undecanoate (DMAU) – androgen receptor agonist

Question 22

Concerns for Male Contraceptive Pill

Answer 22

Concerns over side-effects including sexual dysfunction & weight gain