well, theres still condoms.
i mean, if your not wanting another child you and your partner have to be responsible about how you go about safe sex and not getting pregnant or fearing you could be pregnant.
Make the effort to use a condom instead of just say oh well!
its not that hard to remember if you already have 3 little ones running around.
Can and would another one fit into your routine right now? [this is not meant to be offensive]