The overall number of cases of STIs is:

Choice A reason: Congenital anomalies of the central nervous system are not a common complication of GDM, as they usually occur in the first trimester, before GDM develops. However, GDM can increase the risk of other congenital anomalies, such as cardiac defects or neural tube defects.

Choice B reason: Preterm birth is a possible complication of GDM, as it can be caused by maternal hypertension, preeclampsia, or placental abruption. However, it is not the most likely complication, as GDM can also delay the onset of labor and prolong the pregnancy.

Choice C reason: Low birth weight is not a typical complication of GDM, as it is more associated with intrauterine growth restriction (IUGR), which is caused by placental insufficiency. GDM can cause the opposite problem, which is excessive fetal growth.

Choice D reason: Macrosomia is the most common complication of GDM, as it is defined as a birth weight of more than 4,000 grams (8.8 pounds). It is caused by the excess glucose crossing the placenta and stimulating the fetal insulin production, which leads to increased fat deposition and organ enlargement. Macrosomia can increase the risk of birth trauma, shoulder dystocia, and neonatal hypoglycemia.

Choice A reason: CD4 counts are not used to detect HIV, but to monitor the progression of the infection and the immune system status. CD4 cells are a type of white blood cell that HIV targets and destroys. A normal CD4 count ranges from 500 to 1,500 cells per microliter of blood. A low CD4 count indicates a high risk of opportunistic infections and AIDS.

Choice B reason: Virus is a vague term that does not specify what kind of virus is being detected. HIV is a type of virus that belongs to the retrovirus family. It is difficult to detect the virus itself, as it hides inside the host cells and has a low concentration in the blood. Therefore, most laboratory tests focus on the antibodies that the body produces in response to the virus.

Choice C reason: HIV antibodies are the most common way to detect HIV, as they are produced by the immune system to fight the virus. Antibodies are proteins that bind to specific antigens (foreign substances) and mark them for destruction. HIV antibodies can be detected by a blood test, a saliva test, or a rapid test. However, antibodies may take several weeks to develop after exposure, so a negative test does not rule out the possibility of infection.

Choice D reason: CD8 counts are not used to detect HIV, but to monitor the immune system response and the viral load. CD8 cells are a type of white blood cell that kill infected cells and secrete antiviral substances. A high CD8 count indicates a strong immune response and a low viral load. A low CD8 count indicates a weak immune response and a high viral load.