Definition of Fertility

Conception Slideshow

Fertility: The ability to conceive and have children, the ability to become pregnant through normal sexual activity. Infertility is defined as the failure to conceive after a year of regular intercourse without contraception.

Infertility is on the rise in many countries. The proportion of women in the US having their first baby at or after age 30 has quadrupled since the mid-70s. This is important because the probability of having a baby decreases by 3 to 5% a year after age 30 and even faster after age 40. The switch from condoms and diaphragms to nonbarrier methods of contraception has also raised the risk that an STD (sexually transmitted disease) will compromise the ability to conceive and bear a child.

Fertility depends on many factors including the production of a sufficient number of healthy sperm by the male, delivery of the sperm into the vagina, passage of the sperm through the uterus up into the fallopian tubes, and penetration of a normal ovum (egg) by one of the sperm. A successful pregnancy also requires that the fertilized ovum become implanted in the lining of the uterus.

To conceive a child, a woman must ovulate -- she must release a mature egg from one of her ovaries --and her male partner must ejaculate tens of millions of mature, motile sperm. While sperm form throughout a man's reproductive life, a woman is born with all the eggs she will ever have. Over the years, her supply is depleted (of about 7 million eggs present at birth, only 400 make it to ovulation) and the remaining eggs age, diminishing their reproductive capacity.

A sperm must be reach and penetrate the egg as it travels from the ovary to the uterus. The fertilized egg must then be able to divide many times, implant in the uterus, and form the placenta that is its lifeline until birth. If the fallopian tubes have been damaged by pelvic infection, or there is endometriosis (misplaced growth of the uterine lining), fertilization or implantation may not be possible.

A normal menstrual cycle involves the release of an egg once a month. That egg can survive up to 24 hours. The easiest way to know the fertile time is to chart the menstrual cycle on a calendar. A woman is most likely to be fertile 10 to 14 days after the start of menstruation.

A woman can better detect ovulation by recording her basal body temperature, using a special thermometer (available at pharmacies) to take her temperature each morning after waking, before doing anything else (including going to the bathroom) and record the reading on a chart that comes with the thermometer. When a woman ovulates, her basal body temperature rises about one degree and remains elevated until her next period.

Ovulation predictor kits (sold in pharmacies) depend on sampling the cervical mucus (which thins at ovulation to aid in transporting sperm) and measuring hormonal changes in urine (estrogen levels rise at the start of a woman's most fertile period and a rise in LH (luteinizing hormone) indicates that ovulation is likely to occur within 24 to 36 hours.

Sperm can be examined if a semen sample is given to a laboratory or fertility specialist within two hours of ejaculation. A common problem is a varicocele, or varicose vein in the testicles, that interferes with sperm development. Surgery can correct this problem in more than half of cases.

It is usually recommended that for women under 35, the use of ovulation-timing methods should be limited to a year, and women over 35 should not wait over 6 months before consulting a doctor who is expert in infertility.