You are born with the number of eggs you are going to have throughout your life. Unlike male sperm, which is created anew after every ejaculation, the female eggs are created in utero and stop when you are born. So, the egg that you ovulate at age 40 is now 40 years old and that DNA has the potential to undergo degeneration, and it is this degeneration that is the chromosomal abnormaility.
Although it is possible for men to father children into old age, the genetic quality of sperm, as well as its volume and motility, all typically decrease with age. In other words, older sperm are less likely to result in a successful pregnancy and, moreover, the cumulative fragmentation of sperm DNA over time increases the likelihood that a small fraction of men will pass on achondroplasia and transmit multiple genetic and chromosomal defects. For example, the percentage of sperm with highly damaged DNA, comet extent, DNA break number, and other comet measures has been found to be significantly higher in men aged 36–57 years than in those aged 20–35 years. Advancing paternal age has been implicated in a number of possible health effects. One particularly well-studied connection is the link between advancing age and autism. For example, one study of 943,664 children less than 10 years old, found that, with confounding variables controlled, the risk of autism increased with increasing paternal age. No age related effects on sperm were noted in separate control groups recruited in different geographical locations, indicating that dietary habits, lifestyle or ethnicity could play a part in the quality of sperm.
2. Lucy had both her left ovary and her right uterine tube removed surgically at age 17 because of a cyst and a tumor in those organs. Now, at 32, she remains healthy and is expecting her second child. How could Lucy conceive a child with just one ovary and one uterine tube, widely separated on opposite sides of the pelvis like this? (Note: She did not have artificial insemination or in vitro fertilization.)
See this:
https://biology-forums.com/index.php?topic=15426.0The surgeon must have been incompetent, failing to seal off either the uterus where the right uterine tube had been, or the end of the left uterine tube where the ovary had been. Conception can be explained, but this would result in an ectopic pregnancy that would most likely be surgically removed and not lead to a child!
Anyway, the ovary releases an egg monthly. It goes into the abdominal cavity. Sperm swim toward the egg wherever it is (through whichever of the openings that the inept surgeon failed to seal). Fertilization occurs. It's an ectopic pregnancy. The mother is taken to the hospital, and the embryo is removed and an attempt to implant it into the uterus is made.
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