I’ve seen the figures 4.2% given for chareidi growth rates in Israel. (Growth rates as it pertains to shidduchim may differ slightly from growth rates on a society wide demographic basis, being as the only real numbers that are to be compared are the number of children born in one year to the number of children born X number of years later. For example, if 90% of a society gets married, and the statistical growth rate is 4%, the actual relevant growth rate is actually 10% higher than that figure, being as the people that never got married drag the numbers down but don’t actually have any relevance to the number of people entering the quote unquote shidduchim pool, which are the kids from the families that did get married.) The number for Ultra Orthodox population growth rates in the USA according to some studies has been pegged at about 3.6%. In a vacuum, given the 5% birth rate gender disparity, this would call for a 17 month age gap on average to even out the numbers. This is in fact approximately the average age gap in Europe and Israel, and there is much less of a perceived crisis there. In communities like the Chassidim in North America where the girls are on average the same age or a bit older, there are too many boys (due to the birth rate disparity).
You bring up a good point with OTD rates (boys being more likely to be disabled or deceased is not so relevant to our community). It’s hard to get numbers, but i have seen statistics that a solid 1%-3% more boys (which is a huge chunk) are what would be considered “OTD” than girls. Again, this depends on definitions of OTD.
There are plenty of other factors to be taken into account, such as developmental delays, personality disorders, and major mental health disorders, and what the prevalence rates are for each gender, and much more. There’s a myriad of different factors that need to be gone through. All I’m saying is that an overly simplistic “There’s 5% population growth, so for every 100 boys born in 2000 there’s 115 girls born in 2003, and that’s the answer to why there are issues with shidduchim”, is ignorant of both the actual math and the plethora of other factors at play that someone seeking to drive meaningful change would need to investigate.