BACKGROUND: Globally an estimated 20.5 million liveborn babies are low birthweight (LBW) each year, weighing less than 2500 g. LBW babies have increased risk of mortality even beyond the neonatal period, with an ongoing risk of stunting and non-communicable diseases. LBW is a priority global health indicator. Now almost 80% of births are in facilities, yet birthweight data are lacking in most high-mortality burden countries and are of poor quality, notably with heaping especially on values ending in 00. We aimed to undertake qualitative research in a regional hospital in Dar es Salaam, Tanzania, observing birthweight weighing scales, exploring barriers and enablers to weighing at birth as well as perceived value of birthweight data to health workers, women and stakeholders. METHODS: Observations were undertaken on type of birthweight scale availability in hospital wards. In-depth semi-structured interviews (n = 21) were conducted with three groups: women in postnatal and kangaroo mother care wards, health workers involved in birthweight measurement and recording, and stakeholders involved in data aggregation in Temeke Hospital, Tanzania, a site in the EN-BIRTH study. An inductive thematic analysis was undertaken of translated interview transcripts. RESULTS: Of five wards that were expected to have scales, three had functional scales, and only one of the functional scales was digital. The labour ward weighed the most newborns using an analogue scale that was not consistently zeroed. Hospital birthweight data were aggregated monthly for reporting into the health management information system. Birthweight measurement was highly valued by all respondents, notably families and healthcare workers, and local use of data was considered an enabler. Perceived barriers to high quality birthweight data included: gaps in availability of precise weighing devices, adequate health workers and imprecise measurement practices. CONCLUSION: Birthweight measurement is valued by families and health workers. There are opportunities to close the gap between the percentage of babies born in facilities and the percentage accurately weighed at birth by providing accurate scales, improving skills training and increasing local use of data. More accurate birthweight data are vitally important for all babies and specifically to track progress in preventing and improving immediate and long-term care for low birthweight children.