In calendar method of contraception, first day of feile period is?
10th day of shoest menstural cycle
18th day of shoest menstural cycle
10th day of longest menstural cycle
18th day of longest menstural cycle
Ans. is `a' i.e. 10th day of shoest menstural cycle o Shoest period gives information about the first day of the feile period. The shoest cycle minus 18 days gives first day of feile period. For example, in a cylce of 28 days (most common), first day of feile period will be 10th day of cycle (28 -18 =10). o Longest period gives information about the last day of the feile period. The longest cycle minus 10 days gives the last day of feile period. For example, in a cycle of 28 days, last day of feile period will be 18th day of cycle (28 - 10 =18).