A 24-year-old primigravida from rural Maharashtra presents to the primary health centre at 14 weeks of gestation for her first antenatal visit. She is asymptomatic with a blood pressure of 110/70 mmHg. On examination, the uterus is just palpable above the pubic symphysis. The health worker counsels her on the antenatal care package. Which of the following investigations is NOT part of the mandatory first-trimester antenatal screening package as per NRHM guidelines?