Two things to keep in mind:
1. The chances of a woman getting pregnant from pre-*** are pretty low...even if you're having sex with a woman who is in her biological prime. Not zero percent, but pretty low.
2. Older women have a hard enough time getting pregnant from good old fashioned full-blast ejaculation (let alone pre-cvm). Women in their 30's have to try for months (sometimes years) to get pregnant.
Now combine those two low probability events, and your odds of getting a 30+ year old chick pregnant this way are pretty negligible. Having said that, there are other, more important reasons to wear rubber.