The overall number of cases of STIs is:

Choice A reason: HPV is a common STI that causes genital warts and can lead to cervical cancer. It can be transmitted by any sexual contact or by skin to skin contact. A vaccine is available to protect against some strains of HPV.

Choice B reason: Genital herpes is an STI that causes painful blisters and sores on the genitals. It can be transmitted by any sexual contact or by skin to skin contact. There is no vaccine for genital herpes, but antiviral medications can reduce the symptoms and frequency of outbreaks.

Choice C reason: Chlamydia is an STI that causes inflammation and discharge from the genitals. It can be transmitted by any sexual contact. There is no vaccine for chlamydia, but antibiotics can cure the infection.

Choice D reason: Gonorrhea is an STI that causes pain and discharge from the genitals. It can be transmitted by any sexual contact. There is no vaccine for gonorrhea, but antibiotics can cure the infection.

Choice A reason: This is incorrect. Decreased production of erythrocytes (red blood cells) is a consequence, not a cause, of iron deficiency anemia. Iron is needed to make hemoglobin, the protein that carries oxygen in the red blood cells. Without enough iron, the body cannot produce enough hemoglobin or red blood cells¹.

Choice B reason: This is correct. Inadequate intake of iron is the most common cause of iron deficiency anemia during pregnancy. Pregnant women need more iron than nonpregnant women to support the increased blood volume and the fetal growth. If the dietary intake of iron is not sufficient, the body will use up its iron stores, leading to iron deficiency anemia.

Choice C reason: This is incorrect. Dilution of hemoglobin concentration is a normal physiological change during pregnancy, not a cause of iron deficiency anemia. The blood volume increases by 20% to 30% during pregnancy, while the red blood cell mass increases by only 15% to 20%. This results in a lower concentration of hemoglobin in the blood, but not necessarily a lower amount of hemoglobin or iron³.

Choice D reason: This is incorrect. The fetus establishing iron stores is not a cause of iron deficiency anemia during pregnancy, although it can contribute to it. The fetus needs iron for its own development and growth, and it obtains iron from the mother through the placenta. The fetal iron demand increases in the second and third trimesters, when the fetus accumulates iron in its liver and other tissues. This can deplete the maternal iron stores, especially if the mother does not consume enough iron.