Though he was born female, Beatie underwent a sex change operation a decade ago and became legally male.
Two years ago, he and his wife Nancy - who have been together since Beatie's operation - decided to start a family.
Nancy had previously had a hysterectomy but Beatie was able to conceive as he had opted to retain his female reproductive organs at the time of his sex change operation.
He stopped taking testosterone and began the process of artificial insemination once his menstrual cycle had resumed.
An initial pregnancy almost ended in disaster when Beatie conceived ectopic triplets and had to undergo emergency surgery, but a second attempt was more successful and in March he announced the news in the gay, lesbian and transgender magazine the Advocate.