40% of registered births in Spain in 2023 were to mothers aged over 35.

• At the age of 30 a woman has half the probability of becoming a mother, and from the age of 35 onwards this probability decreases greatly.
• The doctors specialising in reproductive medicine at Instituto Bernabeu warn that delaying motherhood increases the risk of difficulties in conceiving.
• According to the latest INE report, only 320,656 children were born in 2023, 24.7% less than 10 years ago.

The latest statistics from the National Statistics Institute (INE in Spanish) on births in Spain during 2023 show that only 320,656 children were born in the whole of last year, the worst figure since the INE’s historical series began in 1941 and a fall of 24.7% in the last decade. Also shocking is the increase in the average age at which women have children since, as the Instituto Bernabeu team warns, 40.1% of registered births are to mothers over 35 years of age, an age marked as the limit of fertility, since after that age the chances of conceiving decrease significantly for women.

‘Delaying childbearing is one of the main triggers of the falling birth rate because age is one of the main obstacles to achieving pregnancy. At the age of 30 a woman is half as likely to become a mother as she was at 20-24. And after the age of 35 it decreases considerably’, emphasise the specialists at Instituto Bernabeu.

Analysing by age range, there are already as many births to mothers aged 40 and over (10.8% of the total) as to women under 25 (10.7%). The number of births to mothers aged 40 and over has grown by 19.1% in the last 10 years, from 6.8% of all births in 2023 to the current percentage, which has risen to 10.8%. Furthermore, it should be borne in mind that, while in 1980 Spanish women had their first child at the age of 25.6, today that first baby is born to a woman who is 32.6 years old (33.1 years old for Spanish mothers, if the foreign population is taken out of the equation).

This context means that more and more Spanish couples are experiencing problems having children (around 20%) and assisted fertility clinics are dealing with a higher volume of cases. Currently, 1 in 6 children in the world are born through assisted reproduction and, in women over 41 years of age, 50% of births are through egg donation. The average age of patients attending Instituto Bernabeu’s clinics has been increasing over the last 40 years and is now 39.6 years old. If we take into account those who need to resort to egg donation, the age exceeds 42.2.

However, this birth crisis is also influenced by the fact that both sperm quality and sperm concentration have fallen dramatically by 51% worldwide. The rate of decline is enormous: since 1973 sperm concentration has fallen at an annual rate of 1.16% and, at the turn of the century, at a rate of 2.64%.

According to WHO guidelines, a man is considered subfertile when his sperm concentration is below 40 million per millilitre and infertile when it is below 15 million per millilitre. The average obtained in the samples collected by Instituto Bernabeu shows a concentration of 33.5 million spermatozoa per millilitre.