Becoming a parent is full of contradictions: It’s a time in life when love and meaning and joy crash headlong into worry and exhaustion, so much so that some new parents struggle to maintain their own identity. A new study out of the Netherlands suggests that this is especially true for mothers.

Led by researchers at the University of Tilburg, psychologists analyzed survey data collected from more than 84,000 Norwegian women between 1999 and 2008. Women completed surveys at two points during their first pregnancies, and at three points after the birth of their children, with the last being 36 months after birth. Some of the women also completed the same surveys before and after the birth of second, third, and fourth children.

The researchers found a consistent pattern: Women experienced declines in self-esteem during their pregnancies, and then increases in the six months afterwards. But then their self-esteem declined once again, and continued falling. By three years into their child’s life, it was still lower than their original “baseline.” Because they didn’t keep collecting data, researchers don’t know if the dip lasted even longer, but they do know it wasn’t permanent: Women who completed the survey again for a subsequent child had returned to their baseline by the time the process began anew.

The researchers noted several possible reasons for a decline in self-esteem during pregnancy, including physical changes to the body, rampant hormones, stress over the baby’s development, and concerns about the future.

After birth the picture gets more complex, and another clue might lie in the study’s other major finding. At the same key intervals, researchers also asked women to evaluate their relationships. They found that women’s estimation of their romantic partners remained fairly steady during pregnancy, but fell dramatically right after the baby was born. The same effect was also noticeable, to a lesser extent, after subsequent children were born.

Of course, not all women experienced either loss of self-esteem or adverse relationship effects, and this allowed the researchers to identify a correlation: Women who reported lower self-worth also tended to report relationship declines. It’s impossible to say whether one caused the other, but it’s clear that having a troubled relationship and feeling worse about oneself are related experiences, both of which tend to be exacerbated by having kids.

The research is forthcoming in the Journal of Personality and Social Psychology. Previous studies found that, in general, self-esteem has a trajectory over life: High in childhood, declining in adolescence, rising through adulthood and dropping again in old age. The new study adds nuance. Though it doesn’t account for fathers’ experiences, parenting emerges as one of the big challenges when it comes to valuing yourself.