Are you talking about your pregnant fiancé? Since she is black, Look at Cocoa Butter, Vitamin E, or Ambi products. Or look into Nigerian, West African remedies.
This worked for my wife: http://www.boots.com/en/Boots-expert-stretch-mark-oil-150ml_120920/She was plenty pregnant too And afterwards - not a mark, she's dark skinned too & they usually get it worse...
i guess you guys should know since bodybuilders expand like pregnant women