Learning Fertility Basics
Fertility is the natural capability to give life. "To understand fertility, one must first understand the reproductive cycle," says Dr. Alan Gibstein. He is an assistant professor of obstetrics and gynecology at NYU College of Medicine and a women’s heath expert on JustAnswer.com.
The female reproductive system is incredibly sophisticated yet surprisingly simple. Charting fertility — as unromantic and unspontaneous as it may sound — is a helpful tool for women trying to conceive.
Your menstrual cycle
Until you understand your menstrual cycle, you can’t chart your fertility. From puberty to menopause, most women experience a regular monthly period. One woman’s cycle may differ from another’s, but the general pattern is consistent.
The first part of the cycle goes from menstruation to ovulation (exact timing varies):
Day 1 — Bleeding begins and lasts an average three to five days.
- Day 7 — Hormones cause eggs in the ovaries to ripen.
- Day 11 — The lining of the uterus thickens.
- Days 13 to 20 — Additional hormones cause the most ripened egg to be released.
Some women find that this first part of their cycle changes from month to month. Illness, stress, physical activity and even weather can affect the pattern.
In part two of the cycle, the egg travels down the fallopian tube to the uterus. If the egg is fertilized by sperm, it may attach to the lining of the uterus. This is the beginning of pregnancy. If there is no fertilization, the egg cell breaks apart. Between days 25 and 28, hormone levels drop and cause the lining of the uterus to break down. Bleeding occurs, and another cycle begins.
When charting fertility, you must understand that, while the first part of a cycle varies, the second does not. "One thing is constant in all women in the prime reproductive years," says Gibstein. "It is always 14 days from ovulation to the next menstrual period."
Basal body temperature
"A second constant is that progesterone [the hormone that causes the egg to be released] is thermogenic and raises the body's temperature about one-half degree," explains Gibstein.
Basal body temperature (BBT) is the temperature of your resting body, which goes up when you ovulate. By charting your temperature at the same time every day, you’ll see a pattern emerge, and you’ll know the best time each month to try to conceive.
"Only progesterone causes BBT to rise and stay elevated for several days," says Gibstein. "If a woman’s BBT stays up continuously for more than 12 days, then she is pregnant."
If conception does not occur, the absence of pregnancy hormone HCG signals the progesterone secretion to stop, and the lining sheds itself for the next five to seven days.
A woman is fertile for almost one week before ovulation, and examining cervical fluid is another way to know where you are in your cycle.
Several days before ovulation, estrogen levels rise and create a white, sticky cervical fluid. As you get nearer ovulation, the fluid becomes wet, stretchy and clear. "This watery, slippery, highly nutritious substance will support the life and vigor of sperm for five to seven days," says Gibstein. The best time to try to get pregnant is the few days during which this fluid is present.
"It’s not necessary to know exactly when ovulation occurs in order to conceive," says Gibstein. "Healthy sperm need a supply of calories and protein to live, and the cervical mucus provides this." After ovulation, the fluid becomes thinner and/or dries up completely.
Make a calendar available for the sole purpose of charting your fertility. Track when menstruation starts and stops, what your temperature is each day, and how your cervical fluid changes. Transfer these records onto graph paper, and within months a pattern should emerge. You’ll soon be able to tell from your chart when you are about to ovulate.
Remember: Timing is everything.