Present stage of knowledge of reproductive biology concerning natural family planning
Freundl, G.
Genus 54(3-4): 57-74
1998
ISSN/ISBN: 0016-6987 PMID: 12290403 Document Number: 282338
"The common cycle length variation of the woman's cycle in a healthy population is five days.... We believe that the temperature shift in the middle of the cycle is caused by the peripheral effect of estradiol and progesterone on the peripheral circulation. The time from the beginning of the development of an individual spermatozoa to the appearance of a ripe spermatozoon in the ejaculate is about three months. The lifespan of the ripe oocyte is 18-24 hours. The duration of fertilizing capacity of sperm can be five days with decreasing probability; in very rare cases it can be seven days. The probability of conception in our very simple model was 33.3% at ovulation day (day 0)." (EXCERPT)