CAIRO -- Egypt's statistics authority says the population has grown by 1 million over the last six months, reaching 91 million.

The statement issued by authorities on Sunday warned that the runaway population growth is the main obstacle to improving the standard of living. More than a quarter of the population lives in poverty, according to the 2013 census.

Egypt's fertility rate declined throughout the 1980s and 1990s as the government promoted family planning initiatives, but began rising again after 2007, according to World Bank statistics.

The Arab world's most populous country has been struggling to revive its economy after the years of unrest that followed the 2011 uprising.