With the constant decline in the age of childbearing, it is not uncommon today to have your first child at 35 years old. However, at this age, fertility begins to decline, and some pregnancy complications may be a little more common.

Age is the main factor affecting female fertility, the quality of which does not follow a linear curve from puberty to menopause. Female fertility is maximum between 25 and 29 years, decreases gradually between 35 and 38 years, age at which a clear inflection appears. After 40 years, fertility drops rapidly (1).

Getting a pregnancy at 35 may therefore be a little longer than at 20 or 30, but a little less than at 40. According to the simulation model developed by epidemiologist Henri Leridon (2), a woman seeking to have a child has:

• 75% chance of achieving it in 12 months around age 30;
• 66% chance if it starts at 35;
• 44% if it starts at age 40.

According to the model, the risk of not succeeding in having a pregnancy is 8% at 30 years, 15% at 35 years, then 36% at 40 years. The miscarriage rate also increases significantly with age: it is 12 to 15% before 30 years old, it reaches almost 30% between 40 and 44 years old (3).

In terms of fertility, the period around 35 is therefore a turning point: fertility begins to decline but the chances of conception remain honorable. However, they decrease with each cycle, to become weak at age 40 and even more beyond.

That is why specialists recommend not to delay the age of the first pregnancy too much. They also recommend that couples trying to conceive to consult after 6 months of unsuccessful trials if the woman is 35-36 years old (compared to 12 to 18 months if the woman is under 35), so as not to delay the use of a PMA if necessary. Despite all the progress made in the field, the various assisted reproduction techniques cannot compensate for the physiological process of ovarian aging, and their effectiveness therefore decreases with the age of the woman. The chances of successful IVF therefore drop from 25-30% before age 35, to 15-20% after age 38 (4).

In its reference document on pregnancies after 40 years, the National College of French Gynecologists and Obstetricians (CNGOF) (5) recalls from the introduction that “the terms of elderly first-time mother and late pregnancy apply from 35 years of age and especially 40 years “. In most general guides on pregnancy, we talk about “late pregnancy” at 40 years, even 38 years.

In fact, it is recognized that a pregnancy at age 35 is more at risk than a pregnancy at age 30. Certain complications are indeed more important from 35 years – and even more after 40 years. The premature birth rate increases by 5 to 10% after 35 years, while the risk of high blood pressure during pregnancy is multiplied by 5 after 35 years and by 10 to 40 years. The risk of gestational diabetes also increases, as does the risk of hypertension which increases, in the first-time mother, from 4% before age 35 to 7% after.

At age, we must also add other possible risk factors: a pre-existing disease, smoking, overweight, family history, but also the existence or not of previous pregnancies.

The rate of chromosomal abnormality increases with maternal age. For trisomy 21, for a woman aged 30, the risk of giving birth to a child with Down syndrome is 1/965; in 35-year-old women, it is 1/427 and 1/214 at 38 years. The risk of congenital malformations (without karyotype anomaly) also increases significantly with age: from 3,5% between 25 and 34 years, it increases to 4,4% at between 35 and 39 years, and 5% after 40 years (6). The risk of intrauterine growth retardation (IUGR) is also increased after age 35, and even more after age 40.

For a long time, the medical profession placed at 35 the threshold beyond which being pregnant for the first time put both baby and mother at risk. A study (7) carried out on nearly one million women in Norway and Sweden, the results of which appeared in 2013 in the journal Obstetrics & Gynecology, however, lowered this threshold to 30 years. For the authors, women with their first child between the ages of 25 and 29 have the fewest maternal and fetal complications. Between 30 and 34 years old, expectant mothers are five times more likely to give birth to a very premature baby or to have a stillborn child than between 25 and 29 years old. After 35 years, we can therefore logically assume that this risk is even more increased.

Unless there are complications, pregnancy follow-up will be done according to the classic scheme: 7 prenatal consultations at the rate of one per month from the 3rd month of pregnancy, and 3 obstetric ultrasounds. The follow-up can be done by an obstetrician-gynecologist or a midwife, but the opinion of a gyecologist-obsetrician is recommended for pregnancies beyond 35 years, according to the recommendations of the HAS (8). The practitioner will be more attentive to certain points such as tension, and will redouble their vigilance in the event of risk factors other than age (overweight, smoking, etc.).

Screening for trisomy 21 is based, as in all pregnancies, on combined screening in the first trimester. This screening is systematically offered but not compulsory, whatever the maternal age. The latter will be integrated into the calculation of the combined risk alongside the measurement of nuchal translucency at the first ultrasound and the assay of serum markers. As for all pregnant women, a karyotype (by amniocentesis or trophoblast biopsy) will be offered only in the event of a risk greater than 1/250.

With this follow-up, a pregnancy at age 35 generally goes well. The future mother must for her part, also take care to have a good hygiene of life, to take care of herself and to be attentive to the slightest warning sign.