Population of a sub-centre =5000 Crude bih rate= 20 per 1000 mid-year population Therefore, no. of bihs= 20/1000 x 5000=100 Pregnancy wastage factor = 10% (i.e. not all pregnancies result in a live bih, and roughly 10% ANC women have a "wastage" of their pregnancy. Therefore, total ANC= 100+ =110 As a thumb rule, Minimum number of ANC that should be registered at a time= 50%. - Min. No. registered in the sub-centre= 110 x 50/100=55 ~ ~60