Effect of silver nitrate on pregnancy termination in cynomolgus monkeys

The effect of intrauterine injection of 1% silver nitrate on pregnancy was studied in 13 cynomolgus monkeys. The monkeys received, in a random manner, intrauterine injections of 1 ml of either 1% silver nitrate (n = 7) or 0.9% NaCl solution (n = 6) between days 27 and 43 of pregnancy. Silver nitrate injection resulted in vaginal bleeding, beginning 1 or 2 days after treatment, that lasted for an average of 5.3 days. In all of these cases, pregnancy was terminated. Injection of normal saline had variable sequelae, but four of six monkeys were delivered of healthy offspring. All of the silver nitrate-treated animals recycled and, after remating, two of the seven subsequently became pregnant again and were delivered of normal healthy infants. This study demonstrates the efficacy of intrauterine injection of 1% silver nitrate in terminating early pregnancy.