Whereas most research on the intergenerational transmission of fertility behaviour has focused on transmission of the number of children, this paper studies the transmission of the timing of first births. Specific attention is paid to changes in the strength of transmission across cohorts. Theoretically, it is unclear whether the strength of intergenerational transmission of entry into parenthood can be expected to increase or to decrease across cohorts. Event history analyses of data in Dutch registers show a substantial degree of intergenerational transmission in the age at which people have their first child. The degree of transmission from mothers to children increases for successive cohorts. Intergenerational transmission becomes weaker the longer children postpone entry into parenthood. At young ages transmission from mothers to children is stronger than from fathers to children.