Infertility is the inability of a person, animal, or plant cannot reproduce by natural means. It is not the natural state of a healthy adult, except for certain types of species (mostly haplodiploid insects). It is a healthy state to be a child or young animal because they have not yet gone through puberty. This is the start of their reproductive capacity.

In people, infertility is when they are not able to have a baby after having sex for one year without using any contraception. There are many reasons why a person might not be able to have a baby. Some of these reasons can be treated by medical intervention. Male infertility is responsible for 20-30% of infertility cases, while 20-35% are due to female infertility. And 25% are due to problems in both parts. In about 20% of cases, no cause is found. The most common cause of female infertility is when a woman’s ovaries stop working. This means they do not have periods.

In theory, some types of infertility can be overcome by allowing a person to have children at an advanced age. This is because their bodies may have stopped aging as far as possible with regard to fertility. Another reason why infertility exists is that the body may perform a natural selection against those who are less fertile. This is especially true of females since they have a limited number of eggs that age as part of their reproductive system. In some cases, this means that it may become more difficult for them to become pregnant as they get older.

In a biological sense, infertility can be considered as an upgraded version of being infertile. The natural selection applied against those with less fertility is something that has been occurring for thousands of years. In some cases, the actual process of aging can cause infertility. But this is not true in most cases of male infertility today. This process is also known as subfertility.