How do a handle your 14 year old daughter dating a 18 year old transgender boy?

The same way you would handle your 14 year old daughter dating anyone that much older than her. A transgendered individual should be treated with the same respect as anyone else. At any rate, the age gap is still significant, and probably enough of an excuse for you to ask your daughter to break it off, if he really bothers you, however.

That said, you needn't worry about her getting pregnant!

Do keep in mind that transsexual and transgender do not mean the same thing. Transsexual persons get surgery and are a part of the Mainstream Community, while transgender persons are part of the LGBT and rarely get corrective surgery. Of course, FtM persons of either group are much less likely to get surgery than TS women since FtM surgery is much more expensive and painful than MtF surgery, and has a less satisfactory outcome.