Mobile phones are just one factor. I believe the emergence of 24-hour news coverage has done more to discourage reproduction, giving the last generation a sense of futility and inevitable doom with it’s overwhelming glut of negative information.
Other factors are media overload, loss of community (church and other activities), unreasonable expectations (Disney Princess Syndrome) and internet pornography.
It’s not just the media. Don’t leave out the absolute MESS politicians have made of our economic and social environment.