It is not uncommon for women who are pregnant to have a cervical screening test which recommends a referral to colposcopy. It is important to remember that pregnancy has no adverse effect in the progression of abnormal cells (CIN). Equally the presence of a positive HPV test or abnormal cells will not affect the pregnancy or child birth.
If an appointment has been made with a colposcopy clinic then you should attend. Colposcopy will not in any way harm the pregnancy and can provide valuable and reassuring information.
In many cases treatment and even biopsy can be deferred until after the pregnancy. It is very important though, to follow through with the suggested plan, to make sure you return to having normal smear tests