More often than not these days parents are not always married when they start a family. In Sweden the term “Sambo” is used to describe “co-habitees” or “common-law spouse”.
If you have a baby in Sweden and you aren’t married, you need to apply for joint custody. Custody of the baby automatically goes to Mum when the baby is born. Once paternity has been established you can then go to your Municipal “Family Court” or Social Welfare office and request a meeting to set up joint custody.
For more information have a look at the Swedish Court website.