OP: rhythm method

The menstrual cycle is paced by two female hormones that are released into the bloodstream in varying combinations over the course of the month. At one mix, they start your period; at another mix they release an egg. The rest of the time they are moving back between those two events.

Let's follow a 28 day cycle - mine, perhaps. The first day of your flow is Day 1. At that time there is relatively more progestin and less estrogen. An egg has not attached to the wall of the uterus, so it sloughs off. That flow is the nutrients ready to help an embryo form if a fertilized egg arrives. If not, it is disposed of. For the first several days of the cycle, the flow continues. During this time there is a relatively low chance of pregnancy. As the flow ends, the two homones are reversing their mix gradually and after a fortnight, the estrogen peaks and the progestin bottoms out. That is the signal for the egg to leave the ovary and start its trip down the fallopian tubes. This is the time of greatest likelihood of becoming pregnant. It takes the egg a couple days to make it to the uterus. In the absence of sperm to fertilize it, the egg dies and passes on through. At the same time the two hormones begin reversing themselves, again, until at the end of the second fortnight, the flow begins again.

So the most likely time to become pregnant is half way between the two "first days" and the least likely is during the flow. The fertile period for the woman is about two days or a bit more; sperm may live up to two days in the uterus and fallopian tubes. So, at a minimum, you should abstain for about a week or one-quarter of your cycle.

The "rhythm method" is based upon the calendar, counting days. If 100 women use this as their only "protection," 40 + will become pregnant in a year. See the birth control section under natural methods. The basal temperature method involves taking your temperature every day and refining the calendar method by the body's temperature. It is a bit more effective but 20 of those women will still become pregnant. The most sophisticated of the natural techniques requires training, preferably including your partner, identifying the mucous plug that forms in the cervical os. It is rather involved and still not as reliable as most hormonal methods (pill, patch, implant) and not much better than barriers and spermicides, alone.

The natural methods are appropriate for stable relationships where pregnancy will be, perhaps, inconvenient but not a major upset. In the stable relationships, postponing sex for a week is no big deal. In most youthful romances, this is not likely.

Inspite of the above, women have become pregnant on every single day of a cycle, including during their periods. That is why I say the most likely time to become pregnant is when there is a bare penis in the vagina. In women whose period is erratic, so is ovulation. It is simply not adequately predictable for most young women to take a chance with unprotected sex.

Look at your calendar. Identify your last two "first days." Those are your least fertile days. Half way between them is your most fertile time.

Hope this helps.

Brandye

Posted: 26 Sep 23:50