Microgynon (also sold as Microgynon 30) is a combined oral contraceptive that is taken daily to prevent pregnancy. If taken on the first day of your menstrual cycle it provides immediate protection. Each pill contains the two active ingredients; ethinylestradiol and levonorgestrel. These ingredients work to prevent pregnancy in three ways, providing you with reliable contraceptive protection. It is also used to treat endometriosis, premenstrual tension and painful or heavy periods.
What are the additional benefits of Microgynon?
As a combined pill is one of the most reliable contraceptive methods available. It can provide immediate contraceptive protection if taken on the first day of your period, however, it can still be taken two to five days after your period has started, although it may then take seven days for the contraceptive to take effect. Other benefits include:

Prevents the chance of pregnancy after sex by around 99%
Can help to keep your periods regular and lighter
Can reduce the pain you experience before and during menstruation
Some women may also notice that premenstrual symptoms such as mood swings are much less likely to occur

Will it protect me against STIs?
Microgynon pills will not protect you against any sexually transmitted diseases/infections. If you have had unprotected sex and are worried you might have contracted an STI, you should talk to your GP or visit a local sexual health centre.
Alternatively, you can take a look at some of the options available from Allschoolabs.