. . . I was ready to get all medical on you about how there are only a few optimal days for getting pregnant in a woman's cycle. Perhaps my view has been slanted by working with a lot of fertility problems. Common knowledge has dictated that the most fertile time is days 10-17 of a woman's cycle. My response was predicated on this, the idea that this leaves 21 less fertile or infertile days.
However I seem to be wrong (get out the whipping post). Here is an interesting article about why:
Forget everything you have heard about when pregnancy occurs. According to researchers at the National Institute of Environmental Health Sciences, only about 30 percent of women actually have their fertile period between days 10 and 17 of their menstrual cycle. This adds validity to what many 'accidentally' pregnant women, including myself, have long suspected.
Researchers found that the potential for fertility exists on almost every day of a woman's menstrual cycle. Most women in the study were between the ages of 25 and 35--prime reproductive age and the age when menstrual cycles are most regular. The window of fertility was found to be even more unpredictable for teenagers and women approaching menopause.
Data on tests of 213 women during almost 700 menstrual cycles concluded that even women with normally regular menstrual cycles should be advised that their fertile window can be significantly unpredictable. The NIEHS' Allen J. Wilcox, M.D., Ph.D., statistician David Dunson, Ph.D., and epidemiologist Donna Day Baird, Ph.D., described the results of these tests of otherwise healthy North Carolina women in a recent report in the British Medical Journal.
Women who seek to use their cycles to avoid pregnancy may face poor odds, according to the new scientific report. Data from the study suggests that there are "few days of the menstrual cycle during which some women are not potentially capable of becoming pregnant-- including even the day on which they may expect their next menses to begin."
http://womenshealth.about.com/cs/pregnancy/a/whenpregoccur.htmThat said, when life begins is certainly something that remains up for ethical and moral debate. Personally I think that it occurs a lot earlier than pro-choice people think, and a lot later than anti-choice people think. But perhaps it does occur at conception. Unfortunately, I don't remember.