Ready for Love

Thursday, March 24, 2005

Question

What are the safe and risky times of the menstrual cycle if you want to have sex, but avoid pregnancy? Send me a quick answer, please!

Answer

Monitoring your menstrual cycle and restricting intercourse to the "safe" days of the month is an ancient but unreliable form of birth control. The rhythm method or fertility awareness method (also called natural family planning or periodic abstinence) gets 25% of its average users pregnant. Below, I'm going to describe the hormonal changes that a woman's body goes through every month. But I don't want to give you a false sense of security. Visit a birth control clinic to learn about your other options, which can include birth control pills, an IUD (intrauterine device), Norplant, the birth control patch, or a diaphragm or cervical cap.

If you can't go to a clinic, there are still over-the-counter forms (OTC) of birth control that beat counting days till ovulation. You can use a condom in combination with spermicidal foams or gels and get almost the same safety that you'd get from a birth control pill. There's a great bonus in these OTC, no-prescription-necessary forms of birth control: a condom protects you against HIV, hepatitis, and other sexually-transmitted diseases (STDs). The birth control pill won't.

If your male partner doesn't want to use a condom, may I suggest that he's not mature enough to have sex? I don't care if he's fifty years old. A decent guy wants to make sure that his partner has the same good time that he has. Birth control is a sex technique that's as important to learn and become familiar with as foreplay or oral sex. The day after an erotic encounter, everybody involved should feel great, and in order to make the memory a happy one, nobody ought to worry about coming down with syphilis, gonorrhea, herpes, etc. — or an unwanted pregnancy. A guy who refuses to use a condom is not being realistic about the risks of having sex. Somebody who is willing to sacrifice your physical integrity for his own comfort is probably not going to stick around to help you deal with conception, much less child birth and raising a baby. Put your own needs first, just the way that he does, and insist that you have a right to complete protection.

That said, let's proceed to a grand tour of the "average" or 28-day female hormone cycle. Many women don't have a cycle of 28 days, and many others can't predict whether they will begin menstruation in 30 days, 26 days, or some other number. That's why this is a difficult way to accurately predict when you will be ovulating and thus susceptible to pregnancy. You will need to keep a chart of your menstrual cycle for at least two months before you can begin to use the periodic abstinence method of birth control.

Let's arbitrarily say that the cycle begins on the first day of a woman's menstruation or period, and that her period lasts six days. An average woman may see visible bleeding from her vagina for fewer days or more. This blood is being shed from the lining of the womb or uterus. The lining of the uterus had become thicker, in case extra blood circulation was needed to nourish a fertilized egg. But if pregnancy did not occur, that lining is no longer needed, so the body sloughs it off. This cycle is governed by complex interactions between the hypothalamus (a specific area of the brain), the pituitary gland, the ovarian follicle, and the endometrium or uterine lining.

The follicular phase of the menstrual cycle (7-14 days) begins on the last day of bleeding. The lining of the uterus will be very thin at this point. This endometrium will begin to thicken as the follicles in the ovaries secrete estrogen and start preparing to release the next egg or ova. The uterine lining will eventually be 2-5 millimeters thick. Most women have an ovary on either side. They are about the size of an almond. A woman has about 200,000 potential eggs in each ovary, each resting in its own follicle.

On days 15 to 28 (the luteal phase), ovulation occurs. A mature ovum is released on approximately the 14th day of the cycle. It's then referred to as the corpus luteum. Usually only one egg is released at a time. Follicle stimulating hormone (FSH) and luteinizing hormone (LH) are released in sequence by the pituitary gland, which makes about 20 follicles prepare eggs for release. But usually only one follicle matures each month, and when the hormonal cycle is at the appropriate point, it bursts. LH causes the corpus luteum to secrete progesterone. Progesterone plus estradiol causes the lining of the uterus to beef itself up.

The fallopian tubes are four inches long and trumpet-shaped. They arch out from the sides of the uterus. The fingerlike projections at the widest end of each trumpet wrap around the ovaries. They sense chemical messages from the ovary when a follicle bursts, and they sweep the mature egg into the passageway of the fallopian tube. The egg is moved down into the uterus by contractions of the fallopian tube and by hairlike, waving projections that line the tube. It takes about three days for the ova to make it into the uterus.

If the egg is going to be fertilized by contact with sperm, this usually happens in the widest end of the fallopian tube, when the egg is at its furthest point away from the uterus. After the first 12-24 hours of the egg being released by the ovary, fertilization is no longer possible.

If the ovum has not been fertilized, the lining of the womb will be shed again, resulting in another menstrual period. But if an implanted ovum does make contact with the lining of the womb, pregnancy begins. Human chorionic gonadotropin (HCG) is released by the implanted embryo, which sustains it and allows it to continue producing progesterone, thus maintaining the uterine lining and the pregnancy. Progesterone production will be taken over by the placenta in the second trimester of pregnancy.

Sometimes a fertilized egg is not able to implant itself, and it is shed along with the menstrual blood. You probably won't know this has happened because the tissue involved is very small, about the size of a dot on the letter i.

Fertility awareness birth control works much better if you know the length of your menstrual cycles for the previous year. If you have a speculum, a mirror, and a flashlight, you can monitor changes in your cervical mucus and record these on a chart. You also take your temperature each morning before you get out of bed. By charting these facts, you can approximate when you will be ovulating. A woman is able to get pregnant about 5 days a month. Ovulation occurs approximately 12 to 16 days before menstruation begins. So that would be on day 14 of a 28-day cycle. Your fertile days start 5 days before ovulation. Sperm can live for 3 to 5 days in the female reproductive tract. So it's possible to become pregnant if intercourse takes place several days before ovulation. To avoid pregnancy, you need to eschew intercourse or use a barrier 8 to 16 days of every cycle.

Buying a drugstore test to determine when you ovulate is more accurate than the calendar method or taking your own temperature and observing cervical mucus. But it's not a good way to avoid pregnancy. You need to avoid exposure to sperm before and after ovulation. So it's best to consult with a fertility expert, bring your partner along, and decide if you can keep track of all this information and make use of it consistently. There's more information at www.pamf.org/teen/healthinfo/.

By the way, the average age at which women in industrialized Western nations begin to have menstrual periods has declined steadily. It's now less than 12 years old, but 100 years ago, it was 16. Some women's health experts speculate that the presence of estrogen-like polluting chemicals in the environment is responsible for this as well as for lower sperm counts and delayed menopause. If we want to protect our children from unwanted pregnancy and STDs, we have to accept the fact that they need explicit information about anatomy and birth control before they enter puberty. It may sound outrageous to talk about sex education in elementary school or junior high, but these are the ages when our kids most need to know what to expect from their bodies when adult forms of desire begin to move them.