They do discuss the adjusted data a few paragraphs down:
"This difference in reporting, they found, accounted for around 40 percent of the U.S.’s relatively high rate compared to Austria and Finland, a result supported by the CDC report—when analysts excluded babies born before 24 weeks, the number of U.S. deaths dropped to 4.2 per 1,000 live births.
...
When the researchers broke the statistics down by age, they discovered that neonatal deaths were actually less frequent in the U.S. than in Austria and Finland."
Good find, but aren't neonatal deaths are a subpopulation of the overall infant mortality stats, so there is unfortunately, still no clarity. Canada it was noted had similar pre-term birth rate as America (and presumeably higher than Austria and Finland).
It's like a grim logic puzzle where one gets a pile of facts and try to discern the answer.
Country A has higher infant mortality rate than country B.
Country A has higher preterm birth rate than country C.
Country B has a higher neonatal death rate than country A.
etc..
"This difference in reporting, they found, accounted for around 40 percent of the U.S.’s relatively high rate compared to Austria and Finland, a result supported by the CDC report—when analysts excluded babies born before 24 weeks, the number of U.S. deaths dropped to 4.2 per 1,000 live births.
...
When the researchers broke the statistics down by age, they discovered that neonatal deaths were actually less frequent in the U.S. than in Austria and Finland."