Well, you certainly will need to do a DNA test once the baby is born. Only one week between partners is not a compelling amount of time, in other words, no guarantees. And it is only fair to find out for sure, for everyone's sake.
Take care.
Thank you so much for your quick response. My period are pretty regular and only 4 days. Your answer makes me feel better :)
Either guy, depending on how regular your cycles are. More likely to be the current boyfriend, but you can't rule out your ex if your cycles are a bit long or irregular.