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The real deal with sex and the period

  1. Apr 3, 2004 #1
    Guys and gals,

    What is the real deal with safe sex and timing it so there is the least chance of pregnancy?

    I've asked so many people.. So many different ideas. The most common one, that my physiology teacher agrees with, is that one week after the girls period ends is the most dangerous time (highest chance of pregnancy.) They say to leave a 1 or 2 day window on either side of that 7th day to be extra safe.

    By period ending, I mean the bleeding ceases.

    What do you know?
  2. jcsd
  3. Apr 3, 2004 #2


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    It depends on the cycle. Some women have 21 day cycles and will actually ovulate during their period, then the above method is bad. Remember, the basal body temperature does go up just before the luteal phase (when ovulation starts) and alot of women who are trying to get pregnant monitor for this so they can increase their chances of conceiving. Interestingly, they see this spike at different times of their cycle certain months (not exactly at 14 days in a 28 day cycle)..... sometimes they see the spike close to their period etc. , (the assumption is they ovulated) so there are variations in ovulation within the same individual from month to month. So just timing sex based on when your period is will still put you in danger. Measuring basal body temps every day may be a better way...though it is still fraught with unpredictability (some women's cycle flucuate between 21 day cycles, 28, 30 days etc.).
    Last edited: Apr 3, 2004
  4. Apr 3, 2004 #3


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    The real deal? Okay, the best way to time sex so there's the least chance of pregnancy is to have sex beginning no sooner than two months after the woman starts taking birth control pills (and remains on them). Wearing a condom improves the odds, as does combining use of a condom with use of a spermicidal jelly (highly preferable over use of a condom alone as condoms do sometimes break). Note that spermicide needs some time to coat the cervix prior to intercourse, so read the package directions carefully about when and how to apply it (those are directions best read well before the "heat of the moment").

    The most consistent thing in a woman's menstrual cycle is the duration of time from ovulation to the beginning of the NEXT menstrual period (first day of bleeding). Unfortunately, that's not a terribly good predictor since it happens AFTER ovulation. But, the time of ovulation itself can be varied by many things. The number of days of the menstrual period can vary from woman to woman as well...some women can bleed as few as 3 days, others as long as 7 days. On average, the time of ovulation can easily vary by a week in either direction...21 day or 35 day cycles are not at all uncommon. Sperm can live in the female reproductive tract for 2 to 3 days (viability begins to decrease, but all it takes is one survivor), and the egg is most viable for fertilization within the first two days after being ovulated, so this gives about a 5 day window of fertility IF you could predict the precise day of ovulation.

    So, bottom line...the safest time to have sex is when you are prepared to become a parent should pregnancy occur. Even when using birth control, mishaps can happen.
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