Across developed countries, women’s earnings decline sharply following childbirth while men’s earnings remain unaffected. But how will the “motherhood effect” evolve as more women choose not to have children? We examine changes in the motherhood effect on earnings amid rising childlessness in South Korea, the country with the world’s lowest fertility rate. Using an event study framework and administrative data covering the entire population, we find that earnings losses after childbirth have increased across recent cohorts of mothers. We provide suggestive evidence that the expansion of parental leave and a stronger positive selection into motherhood contributed to this trend.