['Medium composition and assay parameters for assessing human sperm hyperactivated motility (HA) were investigated during a time-course study.', 'The incidence of HA was studied, in vitro, in sperm samples incubated in eight different media compositions. HA was assessed using the 7.1 version of the Hamilton Thorn Motion Analyzer (HTM).', "The HA expressed at four hours with human tubal fluid (HTF) was 21.5 +/- 1.1% (mean +/- SEM), and that in Ham's F10 medium was 20.1 +/- 1.4% when the media were supplemented with pregnant women's serum (PWS), a novel support for HA. When fetal cord serum (FCS) was used instead of PWS, the HA exhibited was 16.8 +/- 2.3% and 13.5 +/- 2.35% in HTF and Ham's F10, respectively. Addition of human serum albumin (HSA) to HTF or Ham's F10 media supported HA peak at the four-hour time point (HTF, 19.5 +/- 5.0%; Ham's F10, 10.6 +/- 3.2%). On the other hand, the peak HA expressed in synthetic tubal fluid (STF) supplemented with PWS was 6.0 +/- 0.7% at the two-hour time point. Intra-Menezo B2 medium (IMB2) supported HA at the two- and four-hour time points, but not at six hours. HA appeared much less when Biggers-Whitten-Whittingham (BWW) medium was used."] Does pregnant women 's serum provide a novel support for human sperm hyperactivated motility?