Orthwood is a very uncommon surname. It appears on the IGI in Europe only once -- a Margery Orthwood married in London in 1560. There is little evidence that the surname survived in America. It is possible this surname is a variant of the more common toponymic surname Northwood. (2)
Illegitimate twins, one survived: Jasper Orthwood, b. 29 Jul 1664 Northampton County, Virginia. (1) (2)
(1) John Ruston Pagan, Anne Orthwood's Bastard: Sex and Law in Early Virginia (Oxford and New York: Oxford University Press, 2003).
(2) International Genealogical Index, accessed 19 June 2008.