ɪnðə mˈɪd nˈaɪntiːnhˈʌndɹɪd ˈeɪɾi z, fˈɑːloʊɪŋ kənsˈɜːnz ɐbˌaʊt ˌeɪtʃˌaɪvˈiː, spˈɜːm wˌɪtʃ hɐdbɪn fɹˈoʊzən ænd θˈɔːd baɪ bˈiːpˈæs wʌz jˈuːzd ɪnstˈɛd ʌv fɹˈɛʃ spˈɜːm.
In the mid-1980s, following concerns about HIV, sperm which had been frozen and thawed by BPAS was used instead of fresh sperm.