The study was carried out by researchers at University of Pennsylvania and University of Southern California, who analysed data from 15 countries across three continents and hundreds of years.The 15 developed nations included Sweden, France, Denmark, England/Wales, Norway, The Netherlands, Italy, Switzerland, Finland, the United States, Spain, Australia, Canada, Belgium and Japan. The study states that before the 20th century, the leading cause of infant death was infectious diseases such as diarrheal diseases. However, this underwent a change and now the leading cause of death among newborns is congenital conditions and complications of childbirth and premature delivery.
Researchers also noted that baby boys are 60 percent more likely to be premature, and suffer from conditions arising from being born premature, such as respiratory distress syndrome. They are also at a higher risk of birth injury and mortality due to their larger body and head size.