Obstetric clinic appointment come through?

D • 30, UK 🇬🇧 Mama to a 34 week preemie 💙

So I’m almost 16w and about 3 weeks ago I had two letters come through for appointments- one for my 20w scan and one to attend an ‘obstetric clinic’ (which is this Friday), it never said what exactly it’s for and my other pregnant friends have had no such appointments, anyone have any ideas?