You're wrong about the birth rates and the pay gap being manipulated by statistics though, everything in the GDR was pure and unfiltered shit with terrible consequences except for the women's and family policies.
My main point - again poorly articulated - wasn't the giant drop in 1990, but rather that the family politics actually worked in the first place and increased the number of births, something that West Germany never managed to do and frantically tried to counter with migration. The birth rates of both countries were about the same until the new policies kicked in during the early 1970s. This figure shows it quite nicely.
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The pay gap in East Germany was and still is smaller than in West Germany. It is measured and compared as a ratio, not a difference.