This dissertation examines the changes following the original Two-Child Policy (TCP) implemented in Vietnam in 1988, including the policy's relaxation in 2003, its partial reinstatement for government workers in 2007, and its full restoration of the two-child policy for the ethnic majority in 2009. These policy interventions serve as natural experiments for this investigation, allowing me to explore the evolution of the TCP and its impact on fertility outcomes. By analyzing both the intended and unintended consequences of these policy changes, this research offers valuable insights for policymakers and researchers interested in the social implications of population control measures. Utilizing data from the Vietnam Household Living Standards Survey (VHLSS), I construct an event history of birth to investigate birth outcomes, specifically the probability of conception, using a Differences-in-Differences design. I found that the most affected group—the Kinh ethnic majority working in the public sector—increased their fertility following the policy's relaxation, and the increase continued even after the two-child policy was reimposed. I explored the sub-groups that change their fertility as a response to these policies and detailed some potential mechanisms at play.