It's been reported on NPR: Americans are shrinking, while Chinese and Koreans sprout up. In the New York Times: Adults have become shorter in many countries. In the Guardian: Women and men have grown taller over last century. On Global News: Canadians don't stack up in height quite like they used to. In the Daily Telegraph: British overtake Americans after growing 11 cm in 100 years. By Quartz India: India's women are gaining height faster than India's men, but Indians are still very short.
The study is called "A century of trends in adult human height". It's attributed to a research team called the NCD Risk Factor Collaboration, and the corresponding author is Majid Ezzati, a Professor at Imperial College’s School of Public Health. The research team did a meta-analysis of 1472 studies, all of which were based on direct (not self-reported) measures of height. The aim of the project was to estimate the height, at age 18, of people born each year between 1896 and 1996. When the population sampled was older or younger than 18, the authors used a growth model to estimate height at 18 years of age. When no data on a particular birth cohort was available, they projected observed trends forwards or backwards to get some estimate of the heights of the missing cohorts.
My reaction, upon reading the study, was: “wow, they’ve done a lot of work, and they’ve got some cool data, but I’m not sure I trust the results”.