Splitting the penalty by taking turns? Same-sex mothers' earnings losses in Norway

Mothers typically face earnings losses after having children, also known as the child penalty. However, research has shown that female same-sex couples experience smaller child penalties. Female same-sex couples have a unique advantage when it comes to the child penalty: they can split it by taking turns being the birth mother. But is that the reason for their lower penalty?

Using register data on the entire population of Norway, we study the factors behind this difference. The main reason is fewer pregnancies per mother. Since childbirth itself leads to the biggest income drop, having fewer pregnancies results in lower overall career penalties. Due to high costs and strict regulations on fertility treatments, same-sex couples tend to have fewer children, and only half switch birth parents for a second child. This explains why, on average, mothers in same-sex couples maintain higher earnings in the early years of parenthood.

This study highlights how each new birth is a key driver of inequality and suggests that policies promoting shared parental leave and flexible caregiving could help balance career and family responsibilities. It also raises concerns about inequitable access to fertility treatments, as many same-sex couples have fewer children than they seem to prefer. Ensuring equal opportunities to form a desired family should be a priority, even in relatively tolerant societies.