Natural fertility

Birth control

Natural fertility is a concept developed by the French historical demographer Louis Henry to refer to the level of fertility that would prevail in a population that makes no conscious effort to limit, regulate, or control fertility, so that fertility depends only on physiological factors affecting fecundity. In contrast, populations that practice birth control will have lower fertility levels as a result of delaying first births (a lengthened interval between menarche and first pregnancy), spacing out the intervals between births, or stopping child-bearing at a certain age. Such control does not assume the use of artificial means of fertility regulation or modern contraceptive methods but can result from the use of traditional means of contraception or pregnancy prevention (e.g., coitus interruptus), or from social norms or practices regarding celibacy, the age at marriage and the timing and frequency of sexual intercourse, including periods of prescribed sexual abstinence Ansley Coale and other demographers have developed several methods for measuring the extent of such fertility control, in which the idea of a natural level of fertility is an essential component.

Proximate determinants

Proximate determinants describe variables that affect a female's fertility. There are seven proximate determinants of natural fertility, four of which affect the inter-birth interval:

Populations

Reasons for practice

Common reasons communities or individuals will practice natural fertility include concerns about developing medical conditions (including future infertility), pre-existing health conditions (including PCOS), cost of birth control, religious prohibition, lack of availability of birth control, and lack of information about birth control methods. Location also tends to be a factor in regards to the availability of both contraceptives and education on sexual practice. For example, less developed areas, including, but not limited to those extending throughout inland Africa lack access to the drugs necessary to control fertility or informative lessons describing their correct usage.

Fertile window

The number of children born to one woman can vary dependent on her window from menarche to menopause. Taking into consideration lactational infecundability and the period between conception and birth, the average woman is capable of experiencing around 20 births. However, if the duration of lactation is cut short due to use of a formula substitute or the woman has multiple births, the number of offspring could exceed 20.

Male contribution

Natural Fertility is not only influenced by women and their conscious decisions, but also their male counterparts. Even if a woman is unexposed to contraceptives, lacks knowledge of family planning, or purposly refrains from practicing regulated fertility, she could still struggle to conceive. Over the past half century, there has been an increase in scientific data supporting the decline in male sperm count. The decrease is attributed to various environmental toxins that are accumulating as the planet continues to industrialize. As long as sperm count remains above 60 million per ejaculate, fertility remains normal. Although, more and more males are approaching the 60 million boundary in correlation with the increase of atmospheric toxins. At such low levels, the sperm often are incapable of successfully fertilizing the egg. In result, women tend to run into more difficulties when trying to conceive, even if they are attempting to do so naturally.