The risk of malformation in children increases little with the age of the mother, except for the trisomy 21. It is estimated the risks of giving birth to a child with Down Syndrome 21 to 1 over 1500 to 20 years, and to 1 in 100 to 40 years. At 20, we will not always think about screening, whereas after 40 years, it will be obvious.
Fortunately, trisomy 21 is easily detected by ultrasound in the 1st trimester (the disease is suspected in the nape - thicker - of the fetus), by the tri-test (a blood test), or by amniocentesis
Amniocentesis involves taking amniotic fluid through the skin of the mother's womb. This is done with a thin needle. It is no more painful than an intramuscular sting. The puncture is done after identification, and under ultrasound control. The intervention makes it possible to establish a karyotype of the baby (the map of its chromosomes).
Warning: the problem of amniocentesis is that it can cause a miscarriage. The risk of miscarriage due to amniocentesis is estimated at 1%. And this is not inconsequential in women over 40, who will still need some time to be pregnant again.
Namely: The amniocentesis is (for now) reimbursed by social security, from 38 years.
See also this video:
Amniocentesis is an intervention that can be performed in pregnant women. It involves taking amniotic fluid to look for infections, genetic disorders or metabolic problems, and fetal lung maturity.