The 99.9996% of Times You Have Sex

Pregnancy is caused by conception, the coming together of one sperm and one ovum, whereas contraception is keeping sperm and ova apart.

If you want to get pregnant, then engage in as much consensual penile-vaginal intercourse as you can while being postpubescent and premenopausal.

If you do this, there is an 85% chance you will get pregnant within one year.

For the other 99.9996% of times you are engaged in penile-vaginal intercourse; that is, the times you do not want to get pregnant, you will want to know about contraceptives. Of which apparently, a lot of people do not know about, since nearly 50% of pregnancies are unplanned.

A contraceptive’s effectiveness is measured by the chances of pregnancy within one year.

The near perfect contraceptive is not engaging in penile-vaginal intercourse. There is a 0% chance of getting pregnant when using this contraceptive, unless you are engaging in forms of sex other than penile-vaginal intercourse, like oral sex, anal sex, or mutual masturbation; or you are a gall wasp; or you believe in human parthenogenesis.

The “best contraceptives” are the intra uterine device (often simply called IUD), the Depo-Provera shot, an implant, a vasectomy, and tubal ligation. When using any of these contraceptives, you can expect between a .8% and 3% chance of getting pregnant.

“Very good contraceptives” are the Evra Patch, the pill, and NuvaRing. When using any of these contraceptives, you can expect about an 8% chance of getting pregnant.

“Good contraceptives” are the diaphragm (with spermicide), male condom, and female condom. When using any of these contraceptives, you can expect between a 15% and 21% chance of getting pregnant.

“Fair to mediocre contraceptives” are spermicides, cervical cap, the sponge, withdrawal (also called, the pull-out method or coitus interruptus), and fertility awareness (also called, natural family planning or the rhythm method). When using any of these contraceptives, you can expect between a 25% and 32% chance of getting pregnant.

In consultation with your gynecologist or urologist, choosing your contraceptive should be based on you being aware of the contraceptive’s effective rate and whether the contraceptive matches your personality. For example, if you are a forgetful person, then you probably should not be using the birth control pill which requires you to remember taking it every day.

Choosing your contraceptive should also be based on you knowing at least three physiological facts associated with human reproduction:

(1) Because an ovum can live within the uterus for as long as two days and sperm can live within the vagina or uterus for as long as seven days, the timing of conception does not necessarily coincide with the timing of sexual intercourse.

(2) When a man ejaculates, his ejaculate typically contains about 300 million sperm cells, but before he ejaculates, and without any awareness or feeling, a man often releases a preseminal fluid that contains as many as 100 thousand sperm cells.

(3) Most women’s menstruation cycles vary from month to month and less than 15 percent of women have a 28-day cycle.

So, there it is.

You officially know a variety of contraceptive methods, and you know some basic reproduction physiology.

Now, it is up to you to choose your current contraceptive or change to something new.

Whatever you choose, remember two things:

Remember numbers do not lie, especially when they are effective and failure rates for contraceptives.

And remember the answer to this riddle, “What do you call people who have penile-vaginal intercourse while using spermicides, a cervical cap, the sponge, the withdrawal method, or fertility awareness as their only contraceptive?”

Answer: Future Parents.


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Dr. Don Lucas, Ph.D. is a Professor of Psychology and head of the Psychology Department at Northwest Vista College in San Antonio Texas. He loves psychology, teaching, and research.

If you like this paper, check out Don’s YouTube channel, 5MIweekly:, like his Facebook page:, and check out his Medium site:

I am a Professor of Psychology at Northwest Vista College in San Antonio Texas. My research focus is human sexuality. I also host a YouTube channel, 5MIweekly.

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