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Advanced maternal age

Maternal pregnancy complications

Some numbers

It has long been considered that advanced maternal age begins at the age of 35, however the rate of pregnancy complications notably increases after the age of 40. The latest national statistics show that about 20% of pregnant women today are over 35 years old.


Reduction in fertility and increase in the number of miscarriages

Maternal age Rate of pregnancies after 1 month of trying Rate of miscarriage
25 50 % 5 %
35 35 % 15 à 20 %
40 10 % 25 à 30 %
43 3 % 40 %

Increase in the number of fetuses with a chromosomal anomaly

Maternal age Rate of chromosomal anomaly
25 1/475
35 1/180
40 1/60
43 1/30

Increased number of congenital malformations

The rate of congenital heart defects is 3-4 times higher in women 40 years of age and older. Other congenital malformations – diaphragmatic hernias and club feet, for example – are also more common.

Increased risk of pregnancy complications

Women approaching their forties can sometimes suffer from chronic diseases such as obesity, diabetes, or high blood pressure.

These acquired conditions partly explain why pregnancies are sometimes more complicated.

In addition, maternal age alone is a risk factor for many pregnancy complications:

  • At least 3 times greater risk of developing gestational diabetes
  • At least 3 times greater risk of developing gestational hypertension
  • At least 5 times more likely to develop preeclampsia (35% risk)
  • 3 times more risk of prematurity
  • 1 to 4 times higher risk of fetal death in utero
  • 3 times greater risk of placenta praevia ;
  • 50% risk of caesarean section for women who are in their first pregnancy

Tests and procedures

Each woman is offered prenatal screening for chromosomal abnormalities and congenital anomalies.

The risk of chromosome abnormality is established through the nuchal translucency measurement during ultrasound performed between weeks 11 and 14 and after two blood test sequences.

Major birth defects can be detected with an obstetric ultrasound in the second trimester. Some defects can be diagnosed only during third trimester ultrasounds, however, not all defects can be detected with obstetrical ultrasounds.

Treatment and follow-up care

In certain situations, a medical specialist will recommend ASA® (aspirin) – called “baby aspirin” or low-dose aspirin – as a preventive treatment against pre-eclampsia.

Fetal monitoring is also offered using a non-stress test (NST) or ultrasound, as appropriate.

If delivery does not occur until the 40th week of pregnancy, the specialist will recommend induction of labour or increased fetal monitoring from that time. Delivery will be planned before the 41st week in most cases.

Page by

Dr Lucie Morin

About this page
Updated on 1/25/2021
Created on 12/18/2017
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