Comparing regional neonatal mortality rates: the influence of registration of births as live born for birth weight <500 g in Taiwan.

Objective: To investigate regional variation in the registration of births (still+live) as live born for birth weight <500 g and the impact on the city/county ranking of neonatal mortality rate (NMR) in Taiwan.

Design: Population-based cross-sectional ecological study.

Setting: 20 cities/counties in Taiwan.

Participants: Registered births for birth weight <500 g and neonatal deaths in 2015-2016.

Main Outcome Measures: City/county percentage of births <500 g registered as live born and ranking of city/county NMR (deaths per 1000 live births) including and excluding live births <500 g.

Results: The percentage of births <500 g registered as live born ranged from 0% in Keelung City (0/26) and Penghu County (0/4) to 20% in Taipei City (112/558), 24% in Hsinchu County (5/21) and 28% in Hualien County (9/32). The change in city/county ranking of NMR from including to excluding live births <500 g was most prominent in Taipei City (from the 15th to the 1st) followed by Kaohsiung City (from the 18th to the 14th).

Conclusions: The city/county NMR in Taiwan is influenced by variation in the registration of live born for births with uncertain viability. We recommend presenting city/county NMR using both criteria (with or without minimum threshold of gestation period or birth weight) for better interpretation of the findings of comparisons of city/county NMR.