Final answer:
The rise in blood pressure from 100/60 to 140/90 in a pregnant woman should be highlighted for her obstetrician as it may indicate a serious condition such as preeclampsia.
Step-by-step explanation:
Among the vital sign changes provided, the most noteworthy one for the obstetrician would be the blood pressure increase from a prepregnancy 100/60 to a third trimester reading of 140/90. This change may indicate the development of conditions such as gestational hypertension or preeclampsia, which are significant health concerns during pregnancy. A rise in respiratory rate from 16 to 22 breaths per minute and heart rate from 76 to 88 beats per minute during the third trimester are within normal physiologic changes given the increased maternal metabolic rate and blood volume increase by 30 percent during pregnancy. Additionally, a slight increase in maternal temperature to 99.2°F can occur during pregnancy and is typically not alarming unless accompanied by other symptoms.