Why rusks with mice at birth?
How nice is the Dutch tradition really, it is often cozy.
A baby born always gets a warm welcome. While it sucks up the breast milk, the visit, what comes to bring a baby gift, is always served something delicious. That has been the case since the Middle Ages! Usually it was a sweet thing, and it was always a party. Because that a baby was born and that the mother survived, that was really something to celebrate at the time. The means of care we have today, we didn't have them in the Middle Ages!
The pink and white mice (and also the stamped mice!) , but from 1938 in the Netherlands it really became a tradition at birth. And you know why? Because when De Ruyter offered the royal house mice at the birth of Beatrix. The mice were ORANGE and it was a big look.

Source: https://www.deruijter.nl/Historie
Since then, mice have been part of it, we know it no differently. That's a wonderful tradition, isn't it? The visit but also mother get then rusks with mice. Those mice are, of course, just anise seeds with a layer of sugar. Anise is known for stimulating lactation. Pink is when a girl is born, blue for when it's a boy. But did you know it used to be just white mice that were treated to boys? The blue mice have only been standing since 1994!