09 Dec Let’s talk about contraception
Ask the Lady Doctor – Which contraceptive should I use?
Part 1: Natural Family Planning
Contraception is a delicate subject – but an important one. The best way to prevent unwanted pregnancies and abortions is prevention – and the best contraceptive method is the one that you are comfortable with and will use properly. As long as women are the ones who are getting pregnant, they must take the primary responsibility for contraception. It’s never as simple as Dear Ann Landers claimed–“just hold an aspirin firmly between your knees!”
A bonus with some forms of contraception is that not only do they prevent pregnancy, they also afford a certain amount of protection against sexually transmitted infections, (STI’s). The term venereal disease (VD) is no longer politically correct since sexual intercourse is not the only way to acquire these nasty bugs!
In this first of a 5 part series on the subject of contraception we will look at the fertility cycle and “Natural Family Planning” (also known as “the rhythm method”.) Subsequent blog articles will examine barrier methods, IUD’s, oral contraceptives and other methods of birth control.
Natural Family Planning (NFP) is a method of birth control that is acceptable to some women who are unable to use hormones or who find barrier methods objectionable based on personal and religious beliefs. Basically, this method requires that a woman get to know her body very well. The idea is that one abstains from sexual intercourse during the fertile phase of the menstrual cycle. Unfortunately, the rate of conception with this method is high, approximately 10-15 births per hundred woman years of “exposure”.
The principle is simple. The hormones estrogen and progesterone affect cervical mucus and basal body temperature during a woman’s cycle. It is possible to monitor the characteristics of the mucus and measure body temperature in order to predict ovulation.
Here are the facts:
* Ovulation occurs on only 1 day in each cycle
* the egg lives only 12-24 hours if not fertilized
* Sperm need mucus to survive (without mucus they die within hours)
* Fertility depends on ovulation and satisfactory mucus
Let’s examine the three phases of the fertility cycle.
Phase I–during this time a woman is relatively infertile. Phase I starts with the first day of your menstrual period and continues until a follicle (a spherical structure in the ovary which produces the egg) begins to develop. There can be much potential variation from cycle to cycle making phase I difficult to time.
Phase II–the fertile phase. This phase starts with the developing follicle and ends 48 hours after ovulation. The egg erupts from the ovarian follicle and is viable (i.e. can be fertilized) for 24 hrs. We allow 48 hrs for this phase knowing how imprecise the detection of ovulation can be. Sperm are able to fertilize an egg for 5 days (they just lie around and wait for the egg to show up). So, the combined fertility phase is said to be 6-8 days.
Phase III–absolutely infertile. This phase begins 48 hrs after ovulation and ends with the onset of menstruation.
The idea is to limit sexual intercourse to the absolutely infertile days. So, if we had a way to predict when ovulation occurs then we would have some control over fertility. How do we do that?
The first way is to examine cervical mucus. All women of childbearing age will notice a vaginal discharge called mucus. This discharge is perfectly normal. It is an indication of good health and tells a woman that this is the time when an act of intercourse may cause pregnancy. As stated earlier, cervical mucus changes throughout the menstrual cycle as it is influenced by estrogen. Immediately after menses, there will be little or no mucus. If there is any present it will be thick, tacky and opaque. It is not stretchy but sticky. Indeed, many women experience a dry sensation during this time.
As the follicles in the ovary develop they produce more and more estrogen. The cervix responds to this increase in estrogen by producing a more abundant, thin, stretchy mucus that is clear and watery–resembling raw egg white. There is frequently a sensation of wetness and slipperiness. These are the most fertile days. The peak cervical mucus secretion occurs at the height of estrogen production–this occurs 1-3 days prior to ovulation. However, this time is only identifiable in retrospect. The PEAK RULE states that from the fourth day past the peak, a state of infertility persists until the beginning of the following menstruation.
During ovulation, there is a sudden rise in progesterone which causes a rapid change in cervical mucus. The quantity decreases markedly and the mucus becomes thick, sticky and opaque once again.
If you do not wish to have a child:
* Avoid intercourse during menstruation;
* Avoid intercourse on days when the mucus is present and for at least three days afterwards;
* Avoid intercourse on days of slight bleeding and for at least three days afterwards, when bleeding occurs between one menstruation and the next;
The second way to predict ovulation is by measuring your basal temperature. Basal temperature means “baseline”–i.e. after sleeping, prior to rising or doing any activity. This is your “resting” temperature.
Progesterone has a thermogenic effect, that is to say, it raises our basal body temperature. However, this is a very subtle increase–0.4 to 1.0 degrees Fahrenheit (or 0.5 degrees Celsius)–so you must have a very accurate thermometer! This rise in temperature detects only the end of the fertile phase (our temperature remains elevated for 3 days after ovulation). Thus, if one limits intercourse to the period commencing 3 days AFTER the rise in temperature until the end of the cycle, it is possible to avoid pregnancy.
Today, there are testing kits available at your local pharmacy that can help you to predict when you ovulate as well as apps for your smart phone that can help you to regulate your cycle. Keep in mind that the pregnancy tests that are sold at all pharmacies are extremely accurate.
The information presented here is an overview only. It takes a great deal of determination and commitment to familiarize oneself with one’s monthly cycle and to feel comfortable and confident that you know when your infertile phase begins and ends. Your family doctor can help you with the specifics of learning how to use Natural Family Planning.*
Next topic: Barrier Methods of Contraception
More :
Part-2 : Barrier Methods of Contraception
Part-3 : Contraceptive – IUD
Part-4 : Oral Contraceptive Pill (OCP)
Part-5 : Which contraceptive should I choose?
*For further reading online: Billings Ovulation Method