Re: Women, Pregnancy and Estrogen...Some Facts:)
Thought I'd chime in with some science while we're on topic here:
After menstruation, the follicles surrounding the developing egg (primary oocyte) are stimulated by a pituitary gland hormone (FSH) to develop and mature. Once mature these now called granulosa cells begin to secrete estrogen and its levels get so high that another pituitary hormone (LH) causes the follicle in the ovary to release the almost developed egg into the peritoneal cavity; the fimbrae (brush-like extentions of fallopian tubes) bring the egg into fallopian tube and the egg undergoes secondary meiosis to be completely matured.
Now to the interesting part of this lecture, lol: Since estrogen is the primary hormone responsible for female sex drive its maximal secretion from the follicular cells resulted in its release from the ovary and it is at this same time that females get the 'urge' for intercourse. So you see, the urge corresponds to egg release and if the female goes ahead with the action (hopefully with her husband) there is every chance of pregnancy. The egg can only be fertilized in the first day after ovulation (i.e. release from ovary).
So how amazing is that: females' sex drive is heightened at a time when she is very vulnrable to pregnancy.