L18: contraception and birth control

What are the two key pituitary hormones regulating the female reproductive cycle?

FSH and LH.

What do FSH and LH regulate in females?

The release of oestrogen and progesterone.

What stimulates oestrogen release from ovarian follicles?

FSH and LH.

What happens to one ovarian follicle during the cycle?

It becomes the dominant follicle and secretes high levels of oestrogen.

What does high oestrogen from the dominant follicle cause?

Positive feedback causing an LH and FSH surge.

What triggers ovulation?

The LH surge.

What forms after ovulation?

The corpus luteum.

What does the corpus luteum secrete?

High levels of oestrogen and progesterone.

What effect do oestrogen and progesterone together have on FSH and LH?

Negative feedback lowers FSH and LH.

What happens if pregnancy does not occur?

The corpus luteum degenerates, oestrogen and progesterone fall, and FSH/LH begin to rise again.

What do oestrogen and progesterone do to the endometrium?

Stimulate thickening and development in preparation for pregnancy.

What causes menstruation?

Falling oestrogen and progesterone cause endometrial degeneration.

What is contraception?

The deliberate use of artificial methods or techniques to prevent pregnancy after sexual intercourse.

What are ideal features of contraception?

Highly effective, safe, affordable, simple, acceptable, and not harmful to future fertility.

What are the three broad categories of contraception?

Natural/mechanical/surgical, hormonal, and emergency hormonal contraception.

Name examples of natural/mechanical/surgical contraception.

Male/female condoms, caps, diaphragms, sterilisation, vasectomy, and natural family planning.

Name examples of hormonal contraception.

COC pill, POP, patch, implant, injection, IUD, IUS, and vaginal ring.

What does COC stand for?

Combined Oral Contraceptive.

What hormones are in the combined pill?

Oestrogen and progestogen.

Give an example of a combined pill formulation.

Ethinyloestradiol + levonorgestrel (e.g. Microgynon).

How is the combined pill usually taken?

Daily for 3 weeks followed by a 7-day break.

What is the contraceptive vaginal ring?

A soft plastic vaginal ring releasing oestrogen and progestogen.

How is the vaginal ring used?

Worn for 3 weeks, removed for 1 week, then replaced.

What is the contraceptive patch?

A skin patch releasing oestrogen and progestogen.

How is the contraceptive patch used?

Changed weekly for 3 weeks, followed by 1 week off.

What is the main mechanism of combined hormonal contraception?

It inhibits ovulation.

How does combined hormonal contraception inhibit ovulation?

Oestrogen and progestogen suppress LH and FSH via the hypothalamo-pituitary axis.

What happens when LH and FSH are suppressed?

There is no surge to trigger ovulation.

What other effects does COC have besides suppressing ovulation?

It alters cervical mucus and the endometrium.

What health benefits can COC provide?

Reduced ovarian/endometrial/colorectal cancer risk, more predictable bleeding, less dysmenorrhoea/menorrhagia, acne improvement, and PCOS/endometriosis symptom control.

What is the most common adverse effect of COC?

Breakthrough bleeding.

What are other common COC adverse effects?

Nausea, headache, abdominal cramps, breast tenderness, vaginal discharge changes, and reduced libido.

What does POP stand for?

Progestogen-Only Pill.

What is another name for POP?

The mini pill.

How is POP taken?

Daily without a break.

What are advantages of POP?

Does not interrupt sex, can be used in breastfeeding, and useful when oestrogen is unsuitable.

What is the implant?

A matchstick-sized rod in the upper arm releasing progestogen.

How long does the implant last?

3 years.

What is the contraceptive injection?

A progestogen injection given every 8–13 weeks.

How does POP work?

It thickens cervical mucus, delays ovum transport, inhibits ovulation, and makes the endometrium hostile to implantation.

What are common POP adverse effects?

Irregular bleeding, acne, breast tenderness, libido change, mood change, headache, and nausea.

What is IUS?

A hormone-releasing intrauterine system containing progestogen.

How long does IUS last?

3–5 years.

What is Cu-IUD?

A copper intrauterine device that does not release hormones.

How does Cu-IUD work?

It releases copper to prevent fertilisation/implantation.

How long does Cu-IUD last?

5–10 years.

Which contraceptive methods also protect against STIs?

Barrier methods (male and female condoms).

What is EHC?

Emergency Hormonal Contraception.

What oral EHC options are available?

Levonorgestrel 1.5 mg and ulipristal 30 mg.

How does oral EHC work?

It delays or suppresses ovulation via progesterone receptor effects.

Is levonorgestrel effective after implantation has begun?

No.

When is EHC indicated?

Unprotected sex or suspected contraceptive failure.

What should happen if vomiting occurs within 2 hours of EHC?

Another dose should be taken.