INED published a very interesting report on the fewer teenage births in England and Wales.
https://www.ined.fr/fichier/s_rubrique/25676/536.population.societies.2016.septembre.england.early.motherhood.en.pdf
https://www.ined.fr/fichier/s_rubrique/25676/536.population.societies.2016.septembre.england.early.motherhood.en.pdf