The study was done in Germany. Doesn't make it universally appropriate. Something's going on in Europe though.
There was a big to-do from a French mother not long ago who wrote a book regretting having children.
She regrets having children. And, more so, she has decided that other women ought not to have them, if they know what is good for themselves and for the world. After 13 years of maternal humiliations, she wrote a quick, funny, angry book.
Everywhere you look in France these days, you seem to see its cover: The words NO KID in English, followed by "40 Reasons for Not Having Children" in French. It is a huge best seller. Her 40 reasons are often funny and personal ("Don't become a travelling feeding bottle," "don't adopt the idiot-language of children") sometimes bitter ("you will inevitably be disappointed with your child") and often designed to puncture the idealized notion of motherhood that poisons Western societies.