If the fertility rate remains below 2, it will become harder and harder to wage war. And if it femains below 2 long enough there will be nobody left to wage war (or die in it).
So please sacrifice your precious time, health and money for your future children. Do it for the love of war!
The discrepancy is lower than reported because rural families just didn't report female infants, but regardless, don't give them ideas, they might just buy some slave soldiers from Xi.