A pregnant woman experiencing nausea and vomiting should:.

Choice A rationale: Pouring warm water over the perineum provides sensory stimulation that can trigger the micturition reflex. This is a non-invasive nursing intervention typically attempted before proceeding to more invasive measures.

Choice B rationale: Placing oil of peppermint in a bedpan is a traditional nursing measure. The aromatic vapors are thought to relax the pelvic floor muscles and urinary sphincter, facilitating spontaneous voiding.

Choice C rationale: Analgesics may reduce perineal pain that inhibits voiding, but they do not directly address a full bladder. Medications are generally not the "last resort" for immediate mechanical emptying of the bladder.

Choice D rationale: Urinary catheterization is an invasive procedure that carries a risk of infection. It is reserved as the final intervention when all non-invasive methods have failed to resolve bladder distention.

Choice A rationale:

Perinatal transmission of HIV can occur not only in the third trimester but also during labor and delivery. It is not limited to the maternal circulation alone.

Choice B rationale:

While needlestick injuries are a potential risk for healthcare workers, perinatal transmission to the newborn does not occur through this route.

Choice C rationale:

HIV is not transmitted through the ingestion of amniotic fluid. The virus can be present in the amniotic fluid, but the main route of transmission to the newborn is during delivery or through breastfeeding.

Choice D rationale:

The correct answer. HIV can be transmitted from an infected mother to her child through breastfeeding if appropriate antiretroviral therapy is not administered. Breast milk can contain the virus, putting the infant at risk of infection. Therefore, in cases where the mother is HIV-positive, formula feeding is recommended to prevent transmission of the virus to the newborn.