Objective: To determine the predictive value of quantitative motility
characteristics produced by the Hamilton Thorn Motility (HTM) Analyzer
(Hamilton Thorn Research, Beverley, MA) for in vivo conception. Desig
n: A prospective analysis of 222 couples attending a regional infertil
ity clinic. The measurements were made on a semen sample, and the pres
ence or absence of a treatment-independent conception up to 22 months
later was determined. The semen variables were then correlated to conc
eption. Setting: University based center for reproductive medicine. Pa
tients, Participants: The presence or absence of an in vivo conception
was recorded in 222 couples in whom the influence on fertility of the
female partner was minimized, i.e., normal in terms of history and ex
amination, a regular menstrual cycle, ovulatory (midluteal serum P >18
nmol/L [5.6 ng/mL]), and the outcome of the hysterosalpingogram was n
ormal. The median follow-up time was 13 months (range, 5 to 22 months)
. Interventions: None. Main Outcome Measure: Pregnancy. Results: A num
ber of variables were significantly related to time to conception. Whe
n a forward stepwise analysis was performed, the total number of sperm
atozoa was selected on the first step, and average path velocity was s
elected on the second step. No other variables were selected. The fina
l variables consisted of the total number of spermatozoa and average p
ath velocity. Conclusion: The measurement of quantitative motility and
sperm number using a HTM Analyser is of clinical value.