The report shows that when the first-born child is four-years-old, the mother and father have 4.5 and 7.6 percent lower earnings for each month he or she took parental leave in comparison to those without children.

The duration of the father’s parental leave is also a factor in the future earnings of the mother, with each month of parental leave increasing the mother’s future annual income by nearly 7 percent. This applies even after taking into account how long the mother herself was on maternity leave.

The same can not be said in return however with no correlation found between the duration of the mother’s parental leave and the father’s future annual earnings.

“A more evenly distributed parental leave perhaps contributes to a more egalitarian family and division of labour even after the end of parental leave,” said Elly-Ann Johansson, who carried out the study.

As the study covers annual earnings, the researcher was unable to conclude whether the increased earnings are due to longer working hours or a higher monthly wage.

Due to difficulties in comparing families and how they use their parental leave (in full or part-time), the report instead focused specifically on changes in pay development before and after the birth of the first child, up to the child’s fourth birthday.

“One could imagine, for example, that mothers who value their career and professional life highly both have higher incomes and take out a smaller share of parental leave, in comparison with less career-oriented mothers,” said Johansson.

The report studied 17,000 families who had their first child around the turn of years 1993/1994 and 1994/1995 or 2000/2001 and 2001/2002. The duration of parental leave is measured until the child is three and the income change is measured from the year prior to birth until the fourth birthday.