Luna Memo: Definition

Couple fertility is the probability of pregnancy after one year of regular unprotected sex. Spontaneous couple fertility is around 20–25% each menstrual cycle.

If a woman wishes to become pregnant, 50% of her partners will become pregnant within the first six months of the attempt.

In the animal kingdom, the reproductive output of men and women is considered low.

Indeed, the female fertility period is only 5 days/menstrual cycle. In addition, there is a high rate of spontaneous miscarriage very early in the pregnancy, often without the woman being aware of it. This high rate of miscarriage is linked to numerous chromosome abnormalities that are quickly detected and result in the loss of the embryo.

Human fertility remains very complex, it is a succession of very precise events that can be disrupted for reasons internal to the embryo, and external to environmental factors.

Female fertility

The correct arrangement of the female genital tract will allow fertilisation and implantation in the uterus. The hormonal cycle will be responsible for the quality of ovulation, as well as the maintenance of the development of the pregnancy in the uterus.

For these reasons, pathologies of the reproductive system can lead to a decrease in fertility, as well as a decrease in ovarian reserve with age.

Ovarian reserve will be at its highest during puberty and will gradually decrease until the menopause. This phenomenon reduces the potential for pregnancy significantly around the age of 37.

Without contraception, a woman is fertile for a few days a month.

Indeed, ovulation occurs on the 14th day of the cycle.

Thus, the female fertility period is estimated to be between day 11 and day 16 of the cycle.

It is during this period that regular sexual activity is necessary if you wish to achieve pregnancy.

However, if you have irregular cycles, the fertile period is more difficult to determine. There are a number of tests available, the simplest of which is to take your body temperature every morning: an increase of 0.5 °C is synonymous with ovulation.

Luna helps you

Your fertile period can be calculated with the Luna Diary.

Male fertility

The male fertile period is constant.

Male fertility also depends on anatomical conditions that are compatible with the emission of sperm.

The production of sperm is a continuous process, which begins at puberty and continues throughout a man’s life. Sperm quality will decrease with age, but still allows a man to be fertile longer than a woman (yes, it’s unfair). Male hormones play a very important role in sperm production (spermatogenesis).

Luna Memo: Fertility figures for France

In 2020, 740,000 children were born in France.

The fertility rate per woman is measured at 1.84 children per woman in her lifetime.

This rate of pregnancies is currently decreasing.


Co-authored and scientifically validated by Dr. Jean-Philippe Estrade.

Gynecological and obstetric surgeon, expert in endometriosis at the Hôpital Privé Clairval and the Clinique Bouchard, in Marseille.


Read also: LUNA Explains: Endometriosis And Infertility