Coitus Interruptus - Effects

Effects

Like many methods of birth control, reliable effect is achieved only by correct and consistent use. Observed failure rates of withdrawal vary depending on the population being studied: studies have found actual failure rates of 15–28% per year. In comparison, the pill has an actual use failure rate of 2–8%, while the intrauterine device (IUD) has an actual use failure rate of 0.8%. The condom has an actual use failure rate of 10–18%. However some authors suggest that actual effectiveness of withdrawal could be similar to effectiveness of condoms, and this area needs further research. (see Comparison of birth control methods)

For couples that use coitus interruptus correctly at every act of intercourse, the failure rate is 4% per year. In comparison the pill has a perfect-use failure rate of 0.3%, and the I.U.D. has a perfect-use failure rate of 0.6%. The condom has a perfect-use failure rate of 2%.

It has been suggested that the pre-ejaculate ("Cowper's fluid") emitted by the penis prior to ejaculation normally contains spermatozoa (sperm cells), which would compromise the effectiveness of the method. However, several small studies have failed to find any viable sperm in the fluid. While no large conclusive studies have been done, it is now believed the primary cause of method (correct-use) failure is the pre-ejaculate fluid picking up sperm from a previous ejaculation. For this reason, it is recommended that the male partner urinate between ejaculations, to clear the urethra of sperm, and wash any ejaculate from objects that might come near the woman's vulva (e.g. hands and penis).