Pre-cum...can you REALLY get preggers from this??

So, my boyfriend and I want to be married before having our first child.  We live together, are very committed, and eventually want kids...just wanting to wait until we are Mr & Mrs.
We do not use OC or condoms, but practice withdrawal during my fertile window. My boyfriend sometimes puts out a little pre-ejaculatory fluid during foreplay, and then we proceed to sex. So, my question is, can I get pregnant from this fluid??
Thanks for any insight!