ISTANBUL — He has called women unequal to men. He has demanded that some high school students learn an Ottoman-era script scrapped nearly a century ago. Now, he has described birth control as treasonous.

In his campaign to buttress what he sees as Turkey’s rightful place in the world, the president, Recep Tayyip Erdogan, has offended many who view his assertions as sexist, paranoid or outdated.

The latest came on Sunday, when Mr. Erdogan upstaged a wedding couple with a speech in which he described birth control as a threat to the country’s lineage.

As a witness to the newlyweds, the president urged them to have at least three children, and blamed contraception advocates for hindering the country’s growth.