Answer:
Very good question and the answer is “no” , we do not know specifically why Christ was born when He was.
Many people see the similarity between the 2,000 years between certain significant events in the bible, and since we are coming up on 2,000 since Christ’s resurrection many believe His return will be sometime soon, again around this 2,000 year window.
My thoughts are this (personal, not ones I can prove Biblically)….approx 2,000 years from Adam to Abraham (not David), 2000 years from Abraham to Christ, 2,000 years till Christ return, 1,000 year millennium reign.
That makes up a total of 7 (perfect number) * 1000 years. That would also mean that the new Heavens and Earth would be created for the 8th period, and 8 is always tied to a new beginning in the Bible (just like 8 saved on the ark).
Just speculation since know one knows the exact time or date, but we do know the season and we are certainly in it. 🙂