Yes. Pre-ejaculation fluid may contain sperm, which means pregnancy can occur even when full ejaculation doesn't occur within the vagina.
Withdrawal of the penis from the vagina before ejaculation is one of the oldest methods of birth control. It's free, readily available and has no side effects. Still, withdrawal is unreliable at best — and it offers no protection from sexually transmitted infections.
If you're trying to prevent pregnancy, choose a more reliable type of birth control. There are a variety of short- and long-acting forms of birth control. Ask your doctor to help you understand the options.