This is one of the most asked questions about precum. The short answer is: yes.
If the person has ejaculated recently, some residual sperm can linger in the urethra. So although precum does not contain any sperm itself, there is always the chance it can pick up a few stragglers on its way out.
While pregnancy caused by precum is quite rare, it only takes one sperm to get pregnant. You should always use some form of contraception if you want to prevent pregnancy. Pre-cum is one (of many) reasons why the ‘pull-out method’ – where you have penetrative sex without protection, then pulling out before ejaculating – is NOT a method of contraception.
If your regular method of contraception lets you down, ellaOne is the most effective morning after pill. It is most effective* the sooner you take it, but ellaOne can work for up to five days after unprotected sex. *For verification visit ellaone.co.uk/verify/.