Hidden Heart Risk: How Chronic Hypertension During Pregnancy Affects Your Baby
"New research reveals that chronic high blood pressure in pregnant women can cause heart strain and preeclampsia."
Pregnancy is a transformative journey, but for women with chronic hypertension (cHTN), it can present unique challenges. cHTN affects approximately 7% of all pregnancies, making it a significant concern for expectant mothers and healthcare providers alike. While many are aware of the general risks associated with high blood pressure, new research is shedding light on the specific ways cHTN can impact both maternal and fetal health.
A groundbreaking study has revealed that women with cHTN may experience abnormal myocardial strain patterns during pregnancy, leading to adverse perinatal outcomes. This means that the heart muscle itself is working harder and potentially not functioning as efficiently as it should. Early detection of this strain could be crucial in preventing complications such as preeclampsia and preterm delivery.
This article breaks down the key findings of this research, explains what myocardial strain is, and offers practical advice for managing cHTN during pregnancy to safeguard the health of both mother and child.
Rising Prevalence and Pregnancy Risks
The number of individuals in the United States with chronic hypertension during pregnancy doubled between 2008 and 2021, according to a nationwide review of private health insurance data. Chronic hypertension is defined as persistent blood pressure of at least 140/90 mm Hg before pregnancy or within 20 weeks of gestation. The condition can cause organ damage in the expectant mother and increase the risk of preterm birth or a low-birthweight baby.
Treatment Balances Maternal and Fetal Concerns
Evidence shows that chronic hypertension is associated with higher risks of adverse maternal and perinatal outcomes. Treatment decisions have traditionally had to balance the potential benefits of normalizing blood pressure against theoretical concerns about reduced uteroplacental perfusion and fetal exposure to antihypertensive medication. When blood-pressure information becomes available only during pregnancy, particularly in the second half, distinguishing chronic hypertension from gestational hypertension or preeclampsia may require retrospective assessment.
Defining Chronic Hypertension
The American College of Obstetricians and Gynecologists defines chronic hypertension in pregnancy as blood pressure of at least 140 mm Hg systolic or 90 mm Hg diastolic before pregnancy or before 20 weeks of gestation. The definition also recognizes antihypertensive medication use before pregnancy. ACOG reported that chronic hypertension affected 0.9% to 1.5% of pregnant women and that the maternal rate increased by 67% from 2000 to 2009, with the largest increase, 87%, among African American women.
What is Myocardial Strain and Why Does It Matter?
Myocardial strain refers to the deformation or change in shape of the heart muscle during each contraction. It’s a measure of how well the heart is pumping blood. Think of it like stretching a rubber band: if the rubber band (heart muscle) is too tight or weak, it won’t stretch properly, affecting its ability to snap back and perform its job effectively.
- Increased Cardiac Output: Pregnancy requires the heart to pump 30-50% more blood.
- Systemic Vascular Resistance: Normally decreases during pregnancy, but may not in women with cHTN.
- Plasma Volume: Increases to support fetal development, adding extra load on the heart.
Earlier Treatment After CHAP
Following findings from the Chronic Hypertension and Pregnancy study, ACOG recommends using 140/90 as the threshold for initiating or titrating medical therapy for chronic hypertension in pregnancy. This replaces the previously recommended treatment threshold of 160/110. Recent reviews continue to assess emerging randomized clinical trials, systematic reviews, meta-analyses, and updates to international guidelines.
Treatment Effects Remain Complex
A systematic review and meta-analysis found that chronic hypertension was associated with adverse pregnancy outcomes independently of maternal race or ethnicity. In the limited studies available, treated women with chronic hypertension had a higher risk of small-for-gestational-age infants, although this may reflect a direct treatment effect or the greater severity of hypertension among those more likely to receive treatment. Researchers have also emphasized the need for future studies of the long-term health outcomes of parents and their children.
The Takeaway: Proactive Heart Health for a Healthy Pregnancy
If you have chronic hypertension and are planning a pregnancy, early and consistent monitoring of your heart health is essential. Regular check-ups, echocardiograms, and close collaboration with your healthcare team can help detect any early signs of myocardial strain and allow for timely intervention. Remember, a healthy heart supports a healthy pregnancy, paving the way for a brighter future for both you and your baby.
A Spectrum With Long-Term Consequences
A 2026 systematic review estimates that hypertensive disorders of pregnancy complicate about 10% of pregnancies. It estimates that chronic hypertension accounts for 1% to 2%, gestational hypertension for 5% to 6%, and preeclampsia for 2% to 4%. Reviews also describe chronic hypertension and preeclampsia-spectrum disorders as important contributors to long-term maternal morbidity and mortality.
Earlier Recognition and Better Control
Future work must continue to distinguish chronic hypertension from gestational hypertension based on when elevated blood pressure appears. Chronic hypertension is diagnosed before pregnancy or before 20 weeks, while gestational hypertension is diagnosed at or after 20 weeks. Severe hypertension is defined in the cited CDC material as systolic blood pressure of 160 mm Hg or diastolic blood pressure of 110 mm Hg on two occasions.
Family Impact and Offspring Risk
Research has examined maternal hypertensive disorders of pregnancy in relation to early-onset cardiovascular disease among offspring during childhood, adolescence, and young adulthood. A real-world study reported that chronic hypertension identified before or within the first 20 weeks of pregnancy presents varying risks depending on the timing of diagnosis. Lived-experience research found that emotional responses, physical symptoms or their absence, and concerns about effects on family and community were central themes for people with hypertensive disorders of pregnancy.