Every month from the moment menstruation starts until a woman reaches menopause one, or occasionally more, eggs are released from her ovaries. This egg, called an ovum, moves down the fallopian tube where it may come into contact with sperm and be fertilised. Men can produce more than 300 million sperm in one ejaculation and these sperm are capable of moving through the woman’s cervical mucus, up through the cervix into her uterus and on into the fallopian tube.
Around 85% of couples will become pregnant within the first year of ‘trying’. Half of the remaining couples will get pregnant within two years and half of these remaining couples will get pregnant within three years of trying. The chances of getting pregnant decreases as women get older. Around ten years prior to the onset of menopause women start to get low on healthy eggs. This means a woman’s fertility drops fairly significantly around 38 to 40 years of age. This decline, however, can happen anywhere from 35 to 45 years of age. At the same time the rate of miscarriage increases with advancing age. In your early 20’s around 13% of pregnancies may end in miscarriage. In your early 30’s around 16% of pregnancies may end in miscarriage and by your early 40s almost 50% of pregnancies can end in miscarriage.
Men with normal sperm counts seem to remain capable of fertilisation at any age. There is, however, increasing evidence that their fertility also declines with age.
Infertility is generally defined as a situation where pregnancy is not achieved despite a year of unprotected sexual intercourse where a couple is trying to achieve a pregnancy. The incidence of infertility is estimated to be around 10-15% of all couples. The incidence is increasing due to the trend for women to leave motherhood until later on in life. Other factors such as busy couples having intercourse less frequently, declining sperm counts, sexually transmitted diseases and other harmful environmental factors play a part as well. Some specialists would argue that infertility is in fact nature’s way of spacing pregnancies in a highly evolved species such as ours.
Infertility is divided into primary infertility and secondary infertility. Primary infertility occurs where there has been no previous pregnancy whereas secondary infertility occurs where there has been a previous pregnancy. Many of the causes of these two types of infertility are, however, similar.
Causes of infertility
Infertility has many causes. Approximately one third of the cases of infertility are due to male factors, one third is due to female factors and one third is due to a combination of male and female factors. The main causes can be grouped into the following categories:
- Ovulation problems
- Structural problems (such as blocked fallopian tubes)
- Sperm problems (abnormal sperm, low sperm count, absent sperm) Hormonal or other rare problems
- A mixture of male and female problems
Causes of infertility can be further categorised into male and female factors. Both male and female factors can be involved, making the problem even more complex. What can be a minor infertility problem in a woman and a minor infertility problem in a man when taken together can be a major infertility problem.
It is a misconception that male factors play a minor role in infertility. Male factors account for up to 40% of the cases of infertility. There are controversial theories about whether sperm counts are actually dropping in many Western countries and whether lifestyle factors may be a factor in this. Men may have sperm that are immobile, abnormal, absent or low in number. While only one sperm is needed for fertilisation, you need many to travel up through the cervix into the uterus and then into the fallopian tube in order for that one successful sperm to fertilise the waiting ovum. If the sperm can’t move well or are an abnormal shape and unable to penetrate the ovum then fertilisation cannot occur. There are few medical treatments that can effectively improve fertility in men with these problems. There are, however, lifestyle factors that may help improve sperm counts.
Infertility factors in women are generally due to absent or reduced ovulation, blockage to the fallopian tubes or other structural abnormalities that don’t allow implantation or growth of the baby in the uterus.
Before couples rush off to doctors for investigations they should look at the various lifestyle factors that may be contributing to their problems conceiving:
- Many couples lead busy and often stressful lives. Stress can be a cause of reduced fertility by interfering with ovulation if severe enough, but more significantly it can interfere with the frequency of sexual intercourse.
- Less frequent intercourse will reduce your chance of getting pregnant. Remember at the very most you have twelve chances in a year to get pregnant.
- Being very overweight, very underweight or undertaking excessive exercise can also contribute towards reduced fertility.
- Smoking and excessive drinking in both men and women can reduce fertility. Smoking in women leads to nicotine substances being secreted into the cervix and fallopian tubes and can have a toxic effect on sperm and potential embryos. Smoking and drinking in men reduces sperm count. High caffeine intake can also reduce sperm count in men
- Certain occupations can reduce fertility such as working with certain chemicals. Men who sit down a lot in their job generate increased heat, which can reduce their sperm count.
- Tight clothing for men can also reduce sperm count due to increased temperature. Replacing close fitting underwear with boxer shorts or tight jeans with lose pants may help
Other causes of infertility
Factors other than lifestyle that can cause infertility are:
- Endometriosis, which manifests as painful periods and spotting before a period (this may occur in around 90% of endometriosis).
- Irregular periods mean ovulation will be irregular and of uncertain quality. Seek advice early from your doctor if this is the case with you. Don’t panic! Stress can also cause this
- Infections like pelvic inflammatory disease and blocked fallopian tubes can also cause infertility.
- Having babies late in life is significant as fertility in women declines sharply after the age of thirty-five.