It's a story that doesn't get much hype or explanation.....so I'll try to do this in simple way.
If you ask the German government about the rate....they will tell that it's risen in the past two years (mostly due to incoming immigrants). Before 2013, it was near 1.43 births that came from German women over their lifetime from age 15 to age 45. In the past two years....it rose to 1.5 births. Not exactly a significant number, but it's better than 1.43.
Why the low rate? There are basically four elements to the story.
1. About a hundred years ago....several German 'charity' groups got around to publishing birth-control information. If you asked for it.....you got it. Naturally, this upset political folks and a fair number of men. Knowledge is power.....if applied. Fortunley, the war (WW I) came along, and two million German men didn't come back from the war. While recovery took a few years....German Industry and manpower needs eventually came to be an open-door for German women.
The same episode repeated in the late 1930s, and by 1945....3.6 million German men did not come back. Women at that point were firmly planted in occupations and having a career path that hadn't existed before. Having some desire to just stay home and have four or five kids? There was no desire. As you proceed through the 1960s, with the pill now available and more birth-control options in the 1970s and 1980s....the information factor simply doubled up.
2. Cost of living. Ever looked around at the typical cost of living or the cost of affordable housing in Germany? Go and try to price a three or four bedroom apartment in Koln or Frankfurt. Most average families can't afford it.
3. Average income issue. If you take an average German couple and look at the general income (both working) and deduct the taxation....you start laughing. One member of the couple needs to have a fairly technical background with decent pay....if there was some objective of having three kids.
4. It is commonly accepted that couples might not have any kids at all. You might find some guy who meets up with a German gal, and twenty years later.....still living together....no marriage....no kids...and happy with the situation.
As much as politicians and bureaucrats have tried to invent ways to entice more production....it simply hasn't achieved much of anything. Adding to the whole 'game'....is the fact that studies have shown that even immigrant families arrive and help to some degree to pump up the numbers.....that generation 2.0 and 3.0 (a decade, two decades, and three decades down the line).....all become Germanized and they settle back into the same German dilemma....lower production rates.