Really? I don't think the year of gestation is ever added to someone's age here. It's just that, when you ask people here how old they are, they'll answer based on a)the current year and b)the proximity to their last/their next birthday. So, my sister's birthday, for example, is in August, and she's gonna turn eighteen. Legally, she's still seventeen, however people here would refer to her as "an 18-year old", because she's closer to 18 than she's to 17. Furthermore, the state recognizes her as an 18-year old based on her birth
year, not birthday, which is why she can, for example, have the COVID vaccine (which is offered here for ages 18+).
However, I believe there's also another reason for that. Attached to this report
Γλυκά Νερά: Ο θάνατος ήταν αγωνιώδης και όχι ακαριαίος – Τι δείχνει η ιατροδικαστική έκθεση για τη δολοφονία της Καρολάιν
is a segment of the ME's report, where both C and B's DOBs are listed. Caroline was born on 12/07/2001, and B was born on 20/07/1988, which would make the age difference between them precisely 13 years. That, of course, would, accordingly, make B a "33-year old", rather than a"32-year old", as he's so often described as by the media. Anyways, while I don't find it unusual that Caroline is referred to as "an 20-year old", it could be because a 20-year old being married to a 32/actually 33-year old sounds
slightly better than a 19-year old being married to a 32-year old.