Translation:There are more births in July.
I do think "more numerous" in Greek (because I know it's grammatically correct in English) is a redundancy. Since "numerous" is translated to πολυάριθμος (πολύ+αριθμός) in Greek, περισσότερο πολυάριθμος wouldn't quite fit. At least I've never heard it. That might be just me though. ^.^
(I know you're talking about the English translation, but it might be a bit out of the blue without a Greek equivalent in this case)