Hi, Its a pleasure to answer this question for you. If I were your treating Obstetrician, I would not ignore this symptom as you already have a history of preterm labor. Also the worry itself is enough to raise your blood pressure so early on in pregnancy. I recommend that you get yourself examined as a weakness in the cervix [foremost part of the uterus], or infections commonly cause preterm labor. However , both the causes can be easily treated with bed rest, antibiotics if needed, progesterone supplement and if the cervix is weak by applying a stitch to tighten it [encerclage]. Also since your BP shoots up, it is wise to get a urine examination done for proteins as this may be early onset preeclampsia [a condition specific to pregnancy where Blood Pressure rises and proteins appear in urine] so that it can be treated too. I would like to congratulate you for being vigilant enough to recognize these problems and seek help early on. Hope I was able to help. Also please feel free to ask any further questions to me as preterm labor and preeclampsia are my special areas of interest. Thanks and have a great day.