O'HARA, Pa. - Tagg Romney, the eldest son of presidential candidate Mitt Romney, announced via Twitter that he and his wife Jen have new twin boys, delivered by a surrogate today.

"Happy 2 announce birth of twin boys David Mitt and William Ryder. Big thanks to our surrogate. Life is a miracle," Tagg tweeting, linking to a photo of himself and one of his new sons.

This the second time that Tagg, 42, and his wife, Jen,39,  have used a surrogate. The same surrogate was used for the twins carried their youngest son Jonathan, who was born in August of 2010. Their other three children were not born via surrogacy.

On Facebook, Tagg gave even more details about the birth, confirming that the twins are his biological children. "Jen and I are happy to announce the birth of twin boys, David Mitt and William Ryder," he wrote. "Everyone is healthy and happy. They weighed in at 5 lbs 13 oz and 19-3/4 inches and 6 lbs. 13 oz and 19 inches. A special thanks to our gestational surrogate who made this possible for us. Life truly is a miracle, and we feel so blessed to be able to celebrate the arrival of these precious boys into our family. For those keeping score at home, these are grandchildren numbers 17 and 18 for my parents."

According to the official handbook of the Church of Latter Day Saints, to which the Romney's are members, surrogacy is not encouraged. "The Church strongly discourages surrogate motherhood," the handbook reads.

A Romney aide, when asked about the church's view on the procedure, said that Tagg had made the bishops at his church aware of his family's plans.

Now a grandmother of 18, Ann Romney promptly tweeted her congratulations. "Grandchildren 17 and 18 are here - congratulations @TRomney and Jen! We can't wait to meet David and William," she wrote.

David and William's birth mean that Tagg and his wife are now the parents of both the eldest Romney grandchild - 16-year-old Allie - and the youngest. Romney, who has taken various grandchildren out on the trail with him during the campaign and mentions them often, may have nearly leaked the news of Tagg's upcoming arrival back in September during a town hall in Goffstown, N.H.

"I care about the future of this country, I have 16 grandkids. 17, something like that," he said. "Sixteen. I'm counting ones that aren't hatched yet." At the time, aides to Romney did not know which of Romney's five children may have been pregnant.