Puberty, menarche, menstrual cycle and menopause

Question 1

What is puberty?

Answer 1

Onset of sexual maturity, marked by the development of secondary (adult) sexual characteristics

Question 2

What is the order of puberty in women?

Answer 2

Breast buds; growth of pubic hair; axillary hair; menses begin (menarche)
Growth spurt may then follow (due to increased hormonal release)

Question 3

When does menarche begin and has this rate remained constant over time?

Answer 3

Can occur from around 10y onwards, with an average age of 13y, but can be earlier if:

• Low birth weight
• African
• Short and overweight in childhood
• Urban environment
• Socio-familial pheromone activity (anti-inbreeding mechanisms??)

Question 4

What is the menarche?

Answer 4

The onset of menstruation, normally the final stage of puberty. Can be thought as the hypothalamic-pituitary axis ‘waking’ and ‘waking up’ ovaries

Question 5

How does the hypothalamic-pituitary axis ‘wake up’ in puberty?

Answer 5

After 8y, hypothalamic GnRH pulses increase in amplitude and frequency, such that gonadotrophin like FSH and then LH release increases
These stimulate oestrogen release from the ovary, as well as progesterone
Ovarian hormones then modulate the gonadotrophin release by acting in a negative feedback loop on the hypothalamus

Question 6

What does oestrogen do during puberty?

Answer 6

Responsible for generating secondary sexual characteristics:
-Thelarche, development of breast buds (9-11y)
-Adrenarche, growth of pubic hair (11-12y, dependent on adrenal activity)
-Menarche (13y, but reducing): pregnancy now possible
By 16, most growth has finished and epiphyses fused.

Question 7

Broadly, what occurs during the menstrual cycle?

Answer 7

Hormonal changes cause ovulation and induce changes in endometrium to prepare it for implantation should fertilisation occur.
Menses may start irregular; once oestrogen secretion rises, it becomes more regular

Question 8

What are the stages of the menstrual cycle?

Answer 8

Days 1-4: Menstruation
Days 5-13: Proliferative phase
Days 14-28: Luteal/secretory phase

Question 9

What occurs during the menstruation phase of the cycle?

Answer 9

Start of the cycle (1st day menstruation)
Endometrium shed as hormonal support is withdrawn
Myometrial contraction (which can be painful) also occurs

Question 10

What occurs during the proliferative phase of the cycle?

Answer 10

Pulses of GnRH from hypothalamus stimulate LH and FSH release, inducing follicular growth (negative feedback loop as follicles produce oestradiol and inhibin). This ensures that normally only 1 follicle and 1 oocyte mature
As oestradiol levels rise and reach their maximum, positive feedback on HPA causes LH levels to rise sharply - ovulation follows 36hrs after LH surge
Oestradiol causes endometrium to reform and become proliferative (thickens as stromal cells proliferate and glands elongate)

Question 11

What occurs during the luteal/secretory phase of the cycle?

Answer 11

Follicle that oocyte released from becomes corpus luteum, producing oestradiol but relatively more progesterone
Induces ‘secretory’ change in endometrium (stromal cells enlarge, glands swell, blood supply increases)
At end of luteal phase, corpus luteum starts to fail if egg unfertilised, causing progesterone an oestrogen levels to fall.
Once hormonal support withdrawn, endometrium breaks down, menstruation follows and cycle restarts (constriction of spiral arteries in endometrium allows sloughing of excess tissue)

Question 12

How can menstruation be delayed?

Answer 12

Continuous administration of exogenous progesterones

Question 13

How long can menstrual phases last?

Answer 13

3-8d

Question 14

How long does a typical cycle last?

Answer 14

Classically 28d, but cycles vary greatly (esp in adolescence, where can be 20-45d)

Question 15

Are cycles regular?

Answer 15

Once settled, cycles should be relatively regular

Menarche and peri-menopause can be very irregular

Question 16

When are levels of the following high

a) FSH
b) LH
c) Oestrogen
d) Progesterone

Answer 16

a) Small bursts from 5-14d (peak at 14d)
b) Large peak at 14d
c) Rises at 12-13d, then gradually declines, with second peak at 18-20d
d) Gradual rise until around 18-19d, then slow return to normal at 1d (produced by corpus luteum)

Question 17

What are the stages of follicle development?

Answer 17

Day 1-5: Several antral follicles
Day 5-13 (proliferative phase): 1 mature follicle
Day 14: ovulation
Day 15-28: corpus luteum
Day 28: collapsed corpus luteum

Question 18

What happens at the cervix when oestrogen levels rise?

Answer 18

Increased thinning of cervical mucus to make it more receptive to sperm (clear and stringy)

Question 19

What is menstruation (period)?

Answer 19

Loss of blood and uterine epithelial slough
Lasts 2-7d usually, heavier at start
Normal loss 20-80ml (but hard to quantify)

Question 20

What is the menopause?

Answer 20

When ovaries fail to develop follicles
Without hormonal feedback from ovary, gonadotrophin levels rise
Periods cease (actual menopause), typically around 50y

Question 21

What medication can be used to postpone menstruation?

Answer 21

Typically used e.g. when on holiday
Norethisterone 5mg/8hr PO from 3d before period due until bleeding acceptable or 2 packs COCP consecutively without break
Norethisterone is a progestogen, a progesterone analogue