At first, there was maternity leave. This made sense. A woman who is fabricating and then giving birth to a brand-new human really needs a period of rest. The first maternity leaves - unpaid sill, but with job security - were created in Europe in the 19th century. They usually last from a few weeks to a few years.

Then came paternity leave. But this is perhaps an overstatement, because in most countries it still doesn't exist. The idea was to give fathers a short a break from work for them to get to know their offspring. Generally speaking, paternity leave only lasts a few day and was not designed to include men in childcare.

Finally, parental leave was introduced. Sweden was the first country to make a tiny change in the law in 1974 and turn maternity leave into a gender neutral leave. More than 40 years ago, the Scandinavian country gave mothers and fathers the opportunity to choose which one of them was going to take care of their new babies and for how long. This small shift has gradually spread around the world and is called "parental leave": a public policy for families that has positive results for the economy, for women, for men - and for the children we bring into this world.

Here is what you should know about it.