Final answer:
The most urgent vital sign change to report to an obstetrician in a pregnant woman is a significant blood pressure increase from 100/60 to 140/90 mm Hg, as it may suggest preeclampsia, a potentially serious condition.
Step-by-step explanation:
The vital sign change that should be highlighted for a pregnant woman's obstetrician to address is A) Prepregnancy BP 100/60, third trimester BP 140/90. During pregnancy, while blood pressure (BP) tends to rise moderately to manage the increased blood volume, a significant increase such as from 100/60 to 140/90 is especially noteworthy in the third trimester because it may indicate a condition called preeclampsia, which can have serious implications for both mother and fetus. Since normal blood pressure ranges from 90/60 to 120/80 mm Hg, the increase to 140/90 mm Hg represents a deviation from the expected range and warrants further investigation.
On the other hand, slight increases in heart rate (HR), respiratory rate (RR), and body temperature are generally considered normal as the body adapts to pregnancy changes. A HR increase from 76 to 88 beats per minute, RR increase from 16 to 22 breaths per minute, and a temperature from 98.6F to 99.2F may reflect normal adjustments and are less concerning compared with the BP changes.