A study was carried out to determine whether males contribute to repeated e
arly pregnancy loss. Semen samples were analyzed from proven-fertile men (n
= 51 group I) and from men whose partners presented with early pregnancy l
oss (>3 first trimester abortions, n = 32 group II). Routine analysis, sper
m function tests, and ultrastructural studies of sperms were carried out. F
emale factor could be identified in 25 (78%) couples, and in 7 (22%) no cau
se either male or female could be identified and the semen analysis was nor
mal. Percent morphologically normal did not differ significantly between th
e groups, but increased sperm head abnormalities were seen. The functional
tests were all normal except for a significant decrease in the capacity of
nuclear chromatin to decondense in vitro. The ultrastructural studies showe
d defects of chromatin condensation and irregular nuclei with vacuoles. Thi
s study points to the loss of chromatin integrity as a possible contributin
g factor from males to early pregnancy loss.