I am not so sure about the above statement.
The official circular says
Please refer to this office letter of even number dated 18/04/2007
on the subject quoted above (Commercial Circular No.40 of 2007)
wherein...
more... instructions were issued regarding earmarking of combined
quota of two lower berths per coach in Sleeper, AC – 3 tier and AC – 2
tier for following categories of passengers when travelling ALONE: -
a) Sr. Citizens;
b) Female passengers 45 years of age and above;
c) Pregnant Women.