Donald Trump's daughter Ivanka gave birth to a baby boy on Easter Sunday, moving the Republican presidential frontrunner to pronounce the event "exciting" and "beautiful."

"Jared and I feel incredibly blessed to announce the arrival of Theodore James Kushner," she tweeted on Sunday, announcing the birth of her third child with real-estate developer husband Jared Kushner, 35.

The baby is Trump's eighth grandchild, Vanity Fair reported.

Asked "How did it happen?" on Fox News Monday, Trump said, "We won't get into the details."

"It was very exciting on Easter so we have an Easter baby, which is beautiful," he added.

An executive vice president of her father's conglomerate the Trump Organization, Ivanka Trump, 34, also owns a jewellery and accessories line.

She has been a prominent feature of her father's campaign, stumping for him across the country and on social media.