The 9-valent cervical vaccine will not theoretically delay the onset of menstruation. The cervical vaccine, also known as the HPV vaccine, is a type of vaccine that protects against human papillomavirus infection. Medical research has shown that 99.7% of cervical cancers are caused by HPV infection, so the cervical vaccine is effective in preventing HPV infection. Under normal circumstances, the 9-valent vaccine will not delay menstruation, but some women experience delayed menstruation, the most common is that women of childbearing age experience delayed menstruation because of pregnancy, so once menstruation has been delayed for a long period of time, it should be checked to see if they are pregnant. Delayed menstruation can also be caused by excessive weight loss and changes in eating habits, mental or work-related stress, and over-exertion.