Preterm birth characteristics and outcomes in Portugal, between 2010 and 2018-A cross-sectional sequential study.

In Portugal, 1 in 13 babies was born prematurely. Prematurity was more common in predominantly urban districts, a surprise finding that warrants further studies. Seasonal preterm variation rates also require further analysis and modelling to factor in heat waves and low temperatures. A decrease in the case rate of RDS and sepsis was observed. Compared with previously published results, preterm mortality per gestational age decreased; however, further improvements are attainable in comparison with other countries.