I believe the root of this is the maternity/paternity laws, that give mothers 1-4 years paid maternity leave and give fathers zero paternity leave. The maternity leave is tiered in some way so that the longer maternity leave you take, the less money you get each year. This could lead to either or both of:
- Women who have children get slowed down in their careers since they have a gap of at least one year for each child.
- Employers know that if they take on a woman younger than 40, there's a risk that she'll be gone for 1-4 years, possibly more than once. For the company, this would mean:
- getting a substitute (cost in hiring, training etc.). This training and all experience gained on the job would be lost if there's not space for the substitute in the company once the maternity leave is over.
- the woman, once coming back is unlikely to have developed professionally and may even need some training to get back into the job.