Not 45, 40.
By birth order, about 1 in 5 of those births were first births to mothers over 40.
Which is to say 1 baby in 138 was a first birth to a mother over 40.
The numbers are slightly higher than 2018 because there were fewer births among moms under 40, so those few 40+ births made up a slightly bigger percentage of the overall amount.
Can’t beat biology.