Social & Preventive Medicine In calendar method of contraception, first day of fertile period is? A 10th day of shortest menstural cycle B 18th day of shortest menstural cycle C 10th day of longest menstural cycle D 18th day of longest menstural cycle 💡 Explanation In calendar method of contraception, first day of fertile period is? ✓ Correct Answer: A. 10th day of shortest menstural cycle