Install XPMS Basic Skeleton for Females. So you can use the BBP body. Also includes the .nif's for Pregnancy Armour compatiblity.
Note: BBP has some bugs in it. FORE's patcher fix's most of them. Mine don't. You have bean told.
Note:The .nif's for Pregnancy Armour compatiblity where nifscoped by me becouse I could not get Pregnancy Armour to work. Its a bit out. If you can find a better set, use them.