birth control methods method female use surgically sterile study male 
fathering form acceptable medically birth control childbearing child willing potential 
barrier birth control study method adequate contraception abstinence agree duration 
child bearing birth potential control women use study agree practice 
birth control women potential effective men agree reproductive use childbearing 
birth control potential childbearing agree pregnancy study use test method 
protection partners barrier birth control method willing week childbearing principal 
highly effective method birth sexually control women potential childbearing trial 
birth control use effective study agree adequate acceptable forms form