In theory a woman is fertile from puberty to menopause, that is, as long as there is a menstrual cycle which each month results in the ovulation of a follicle. But in reality fertile capacities decline years before menopause sets in. It is estimated that the reproductive period ends 10 years before menopause (1).

At issue: ovarian aging. In terms of quantity on the one hand: the loss of oocytes by apoptosis (programmed cell death) is a continuous process that begins in utero and continues until menopause. On the other hand in terms of quality: studies on the oocytes used in IVF have shown that the aneuploidy rate (cell that does not have the normal number of chromosomes) of the oocytes increased with age: from 10% to 35 years, it drops to 30% at 40, 40% at 43 and 100% in women over 45 (2). Also, the risk of miscarriage increases appreciably with the years: of the order of 12% around 25 years, this risk reaches 20% at 37 years, 30% at 43 years and rises very quickly beyond (3). In addition, if the endometrium does not age strictly speaking, with age there is an increase in uterine pathologies (fibroma, adenomyosis, vascularization disorders) which can hinder the proper implantation of the egg and be the cause of miscarriage.

Because of these different physiological realities, the chances of conception decrease appreciably after 38 years. According to the computer simulation model developed by French epidemiologist Henri Leridon (4):

• a woman seeking to have a child around 30 has a 75% chance of achieving it in 12 months and an 8% chance of not achieving it;
• 66% chance if it starts at 35 and 15% risk of not getting there;
• 44% if it starts at 40 and 36% risk of not succeeding.

In the end, a woman’s maximum fertility period is 15 to 20 years and is at an average age of between 15 and 35 years (5).

If the main factor limiting fertility is maternal age, that of the father is also taken into account. The optimal fertility rate would correspond to a paternal age of 30/34 years, then would decrease beyond that. It has also been shown that a pregnancy occurs in 6 months with a 20-year-old man, and in 30 months with a 7-year-old (XNUMX).

The paternal age also has an influence on the good progress of the pregnancy and the health of the fetus.

• according to a study carried out by Inserm-Ined (8), the risk of miscarriage increases with the age of the father at a rate of 30% beyond 35 years; this risk is doubled beyond 50 years. In question: an alteration of the genetic material of the spermatozoa with age;
• the frequency of certain chromosomal abnormalities and congenital malformations is markedly increased in children of an elderly father;
• a study by Inserm (9) also showed an increased risk of schizophrenia in the event of advanced paternal age. This risk is multiplied by two from 45 years, then increases linearly with age to be multiplied by 4 after 50 years.

A late pregnancy (after 40 years) is considered a risk pregnancy. An advanced maternal age is in fact accompanied by an increase in maternal and fetal complications with in particular an increased risk of (10):

A late pregnancy (after 40 years) is considered a risk pregnancy. An advanced maternal age is in fact accompanied by an increase in maternal and fetal complications with in particular an increased risk of (10):

• Gestational Diabetes ;
• high blood pressure and pre-eclampsia, especially if advanced age is associated with overweight and / or smoking;
• Preliminary cake;
• cesarean section;
• hemorrhage from delivery;
• maternal mortality ;
• chromosomal anomaly, and in particular trisomy 21. The risk is estimated at 1/1500 births if the mother is 20 years old, 1/1000 to 30 years old, 1/400 to 35 years old, 1/187 to 38 years old and 1/100 to 40 years old years (1). The risk of trisomy 13 and 18 also increases with maternal age;
• congenital malformations: from 3,5% at 25 years, the prevalence increases to 5% at 40 years;
• growth retardation in utero (IUGR);
• neonatal mortality.