Human fertility

Human fertility is defined as a person’s ability to procreate. This has allowed the survival of the species, for which it has, logically, been much appreciated by all cultures and civilizations throughout history as it provided the family with a workforce and thus a livelihood. This capacity to have children has been specially valued among women, with those who managed to have more children standing out socially and those who could not, being repudiated.

Hence there are measures such as the fertility rate, which would be the average number of children born to women who, in a particular society or group, have completed their reproductive cycle.

In fertility, many cultural and biological factors are involved, and often these are interrelated.

On the one hand, we have the cultural aspects such as the role in society of men and women, the division of labor, the type and time devoted to it, as well as the different expectations we have of it. On the other, we are up against the different concepts of sexuality, the age at which sexual intercourse is initiated, reproductive goals, number of children wanted, the age at which you want them, same-sex couples or people who choose to live alone.

We must also bear in mind the role different religions play and the different ethical standpoints of each society. In addition, biological factors such as age, constitute an important, if not decisive point in fertile potential, especially among women and are factors which on many occasions, we are not even aware of, including health professionals,. There is ample evidence that a woman’s childbearing capacity declines with age, reducing not only the ability to get pregnant but also increasing the possibility of having miscarriages or children with chromosomal problems.

This is a clear example of how a biological factor such as age can be related to cultural factors. We currently live in a society that has been postponing the age at which you decide to have children, thus compromising our fertile capacity. In Spain, for instance, the average age at which women have their first child is around the age of 32.

Among men, however, age does not seem to impact so clearly as in women since they are able to have children at older ages. Other factors that may not be as crucial but which are no less important are lifestyle habits. The negative correlation between the consumption of tobacco and fertility has been clearly demonstrated in both men and women, not to mention its negative effects on pregnancy, especially among newborns with low birth weight.

Drinking alcohol in excess can lead to diseases which compromise both sexual intercourse and reproductive capacity. Food habits must also be taken into account, although it is true that traditionally fertility has been associated with women with high weight. One example would be the Venus of Willendorf, but today it has been shown that extreme body mass indices correlate with alterations in reproductive capacity.

The beneficial effect of physical activity on health is generally known. However, excessive exercise (high intensity, over 5 hours per week) is associated with infertility in women with body mass index rates of below 25. It is also the case in women who do intense long duration exercise, who have worse rates in assisted reproduction. In contrast, obese women who do exercise improve their fertility.

Other aspects, such as the influence of previous contraceptive use on fertility, which has preoccupied women wanting to get pregnant, have shown that the rate of pregnancy in these women using anovulatories who had stopped taking them for one year equals that of the population who had never previously taken them. We can say, therefore, that in the final analysis, sterility is independent of prior hormonal contraceptive methods

Finally, STDs are not always related to infertility. It is true that some infections such as those caused by Chlamydia and / or gonorrhoea are also frequent and usually asymptomatic. These are important for their association with sterility and infertility, especially if the infection occurs in the fallopian tubes. Other infections such as syphilis, herpes simplex virus or human papillomavirus do not of themselves cause infertility.

Fertility, therefore, is the result of the interaction of biological, social, cultural and even religious factors. We, as reproductive health professionals should direct our activities and our efforts towards advising and informing both the general population as well as health professionals about the impact of age on fertility, and especially, on women.

Last Updated: November 2017