Hi mama! I'm not sure kung ano exactly ang tinatanong mo, pero if it's about CAS at 26 weeks of pregnancy, maybe you're asking about a medical exam or requirement? I'd suggest checking your prenatal card or asking your OB directly para sure, kasi bawat clinic may kaunting iba-ibang process, and mas safe na marinig mo straight from your doctor. Let me know kung ano exactly ang nasa card mo, or share a photo if you want!