-
Reproductive aging
- • Males can produce viable spermthroughout their adult life, although itdiminishes with age, however, thereare cases of men fathering children well into their 90s
- • Females typically go through menopause around age 50 years andno longer have viable follicles and cannot reproduce
-
Paternal age and fertility
- • At age 24, the probability of aman to produce a pregnancywithin a year of frequent (≥ 3times/week), unprotected coitusis about 92%
- • This probability decreases about3% for every subsequent year
-
Paternal age & chromosomalabnormalities
- • Aneuploidy and other chromosomalabnormalities occur during meiosis inthe testes and these abnormalitiesincrease with paternal age
- • Likely that these abnormal sperm havea reduced ability to fertilize an egg
- • Increase rates of miscarriages inpregnancies from fertilization by spermfrom older men
- • Decreased IQ and cognitive abilities inoffspring of older fathers
- • Increase rates of autism in offspring ofolder fathers
-
Andropause: hormonal changes
• Andropause symptoms emergegradually over decades typicallystarting in late 40s andextending until 70 (compared towomen whose menopause iscomplete within a few months oryears)
- • Gradual decline in testosterone at a rate of 1%per year after age 40 in men
- • During this time the number of Leydig cellsreduces in the testes
- • Appears to be a reduction in the testes ability torespond to gonadotropins
- • Blood supply to testes is also reduced
- • Seminiferous tubules show damage in some oldermen
- • Semen volume, sperm motility and viability alldecrease with age
- • Blood levels of estrogen may rise in older men
-
Andropause signs & symptoms
- • Erections may require more foreplaystimulation
- • Voice may rise a pitch
- • Facial hair growth may decrease
- • Scrotum & penis may reduce in size
- • Seminal vesicles and other accessorystructures may reduce in size (however,prostate can enlarge and develop benignprostatic
- hyperplasia)
- • Decreased muscle mass and strength
- • Osteoporosis may develop
-
Menopause
• Menopause is the permanent end ofmenstrual cycling and menstruationassociated with dramatic reduction orloss of ovarian follicular activity
- • Ovaries go through an abrupt decline,resulting in degeneration of theirfunction
- • Menopause occurs between 45-55years with average age of 52 years inUSA
- • Clinical diagnosis of menopause isdefined when a woman in this agerange has had no menstrual cyclesfor at least one full year
- • Possible for women to ovulate for up to oneyear after menopause has occurred
- • Women can still have eggs and folliclesafter going into menopause, however, thefunction of the follicles and the number ofeggs are both dramatically diminished
- • As women age and go though menopause,there is a dramatic reduction in both thenumber and average quality of eggs
- • As follicles deteriorate, the egg supply isdiminished, which leads to infertility
-
Female reproductive stages (Table 7-1)
- • Prereproductive
- • Early reproductive:
- menstrual cyclesvariable to regular; FSH normal
- • Peak reproductive:
- menstrual cyclesregular; FSH normal
- • Late reproductive:
- menstrual cyclesregular; FSH elevated
-
• Low estradiol → lack of negative feedbackon GnRH → increased FSH & LH levels
• Decline in inhibin also results in ↑FSH
• In women in menopause, the FSH is 10times and the LH is 4 times higher than inyounger women
• Decrease in GnRH pulse frequency in menopause
|
|
