For transnational migrant populations, securing birth documents of newly born children has crucial importance in avoiding statelessness for new generations. Drawing on discussions of sovereignty and political subjectivization, I ask how the fact of birth is constituted in the context of transnational migration. Based on ethnographic data collected from an antenatal clinic in Thailand, this article describes how Shan migrant women from Myanmar (also known as Burma) utilize reproductive health services as a way of assuring a safe birth while acquiring identification documents. Paying close attention to technologies of inscription adopted for maternal care and birth registration, I argue that enacting bureaucratic documents offers a chance for migrant women to bridge the interstice between human and citizen. Birth certificates for migrant children, while embodying legal ambiguity and uncertainty, epitomize non-citizen subjects’ assertion of their political relationship with the state.