Blood pressure is a measurement that reflects the force of blood pushing against the walls of the arteries, and it is a routine check at every prenatal visit. This measurement consists of two numbers: the systolic pressure (the first number), which is the pressure when the heart beats, and the diastolic pressure (the second number), which is the pressure when the heart rests between beats. While it is common for a pregnant person’s cardiovascular system to undergo significant changes, sustained increases can signal potential health concerns for both the parent and the developing fetus. Monitoring these values is important because elevated readings can be an early indicator of specific hypertensive disorders of pregnancy that require careful management.
Understanding Blood Pressure Thresholds in Pregnancy
Medical organizations worldwide generally define hypertension in pregnancy as a sustained blood pressure reading of 140/90 mm Hg or higher, measured on two separate occasions at least four hours apart. This threshold is the primary diagnostic marker for both gestational hypertension and preeclampsia after 20 weeks of gestation. Readings below this level are typically considered within the normal range, though closer attention is warranted as blood pressure rises.
For the non-pregnant population, the American College of Cardiology and the American Heart Association (ACC/AHA) established a classification system that includes an “Elevated” category and a “Stage 1 Hypertension” category. An elevated reading is defined as a systolic pressure between 120 and 129 mm Hg and a diastolic pressure below 80 mm Hg. Stage 1 Hypertension in the general population is defined as a systolic pressure between 130 and 139 mm Hg or a diastolic pressure between 80 and 89 mm Hg.
The American College of Obstetricians and Gynecologists (ACOG) guidelines maintain the higher 140/90 mm Hg threshold for initiating treatment in most cases of high blood pressure during pregnancy. The continued use of this higher threshold is due to concerns about potentially reducing blood flow to the placenta if blood pressure is lowered too aggressively, which could affect fetal growth. Although the 140/90 mm Hg reading represents the point of formal diagnosis, any reading that approaches or exceeds the 130/80 mm Hg range is generally viewed as a warning sign that warrants increased monitoring.
Classifying the 130/70 Reading
A blood pressure reading of 130/70 mm Hg falls below the formal diagnostic threshold for hypertension in pregnancy, which requires a reading of 140/90 mm Hg or greater. The systolic reading of 130 mm Hg is exactly at the lower boundary of what is considered Stage 1 Hypertension in the non-pregnant ACC/AHA guidelines, while the diastolic reading of 70 mm Hg is well within the normal range. Because the diastolic number is low and the systolic number is not sustained at 140 mm Hg, this reading does not meet the criteria for gestational hypertension.
Despite not being classified as a hypertensive disorder, a systolic reading of 130 mm Hg demands heightened vigilance during pregnancy. Studies have indicated that blood pressure readings in the 130–139/80–89 mm Hg range, even if not formally treated, are associated with a higher risk of developing preeclampsia and other adverse pregnancy outcomes compared to individuals with lower readings. Therefore, this reading should be interpreted not as normal, but as a signal for increased surveillance by the healthcare team. The context of the reading matters greatly, as an isolated high number may be due to stress, while multiple readings in this range suggest a sustained pattern of elevated pressure.
Associated Risks: Gestational Hypertension and Preeclampsia
Sustained high blood pressure readings after 20 weeks of pregnancy can lead to a diagnosis of either Gestational Hypertension or Preeclampsia, which are distinct conditions. Gestational hypertension is characterized only by high blood pressure—140/90 mm Hg or higher—that develops after the 20th week in a person who previously had normal blood pressure. The diagnosis does not include signs of damage to other organ systems, such as the kidneys or liver.
A significant concern is that gestational hypertension can progress to preeclampsia, which is a more serious complication. Preeclampsia involves high blood pressure accompanied by evidence of organ damage, most often detected by excess protein in the urine (proteinuria) or dysfunction of the liver, kidneys, or brain. This condition affects approximately 3.4% of pregnancies in the United States and poses a risk to both the parent and the fetus.
The signs of preeclampsia can sometimes appear before the blood pressure reaches the severe range, making symptom awareness important. Common symptoms include a persistent, severe headache that does not improve with standard pain medication, blurred vision, or seeing spots, sudden, rapid swelling of the face or hands, pain in the upper abdomen, or difficulty breathing. The presence of any of these symptoms alongside an elevated blood pressure reading requires immediate medical attention, as untreated preeclampsia can lead to serious complications like stroke or HELLP syndrome.
Next Steps for Monitoring and Care
For a reading like 130/70 mm Hg, the first step is to establish a pattern of measurement through home monitoring, if advised by a healthcare provider. When taking at-home readings, it is important to sit quietly with a supported back and feet flat on the floor for five minutes before taking a measurement. Taking two measurements, at least one minute apart, and recording the second one provides a more accurate assessment.
Lifestyle modifications can support blood pressure management, including prioritizing rest and maintaining adequate hydration. While dietary changes, such as reducing sodium intake, are generally recommended for heart health, any major shift in diet should be discussed with the provider.
The most important action is knowing when to contact the healthcare team immediately. If blood pressure consistently rises to 140/90 mm Hg or higher, or if a single reading reaches 160/110 mm Hg, the provider must be contacted right away. Furthermore, any reading combined with symptoms suggestive of preeclampsia, such as a severe headache, visual changes, or upper abdominal pain, warrants immediate medical evaluation, regardless of the numerical blood pressure value.