LetterContent.SenderGender (Word)
Returns or sets the gender used with the salutation. Not used in the U.S. English version of Microsoft Word. Possible return values are wdGenderFemale - Female gender, wdGenderMale - Male gender, wdGenderNeutral - Neutral gender, wdGenderUnknown - Unknown gender.
This property may not be available to you, depending on the language support (U.S. English, for example) that you've selected or installed.
ActiveDocument.CreateLetterContent.SenderGender = wdGenderFemale