From the Guidelines
A heart rate of 140 beats per minute at 32 weeks pregnant is concerning and warrants prompt medical attention. According to the most recent guidelines, a heart rate above 130 beats per minute is considered a maternal early warning criterion 1. During pregnancy, your heart rate naturally increases by about 10-20 beats per minute above your pre-pregnancy baseline, but a sustained heart rate of 140 is higher than expected. This could be due to several causes including dehydration, anemia, anxiety, fever, infection, thyroid issues, or potentially more serious cardiac conditions.
Some key points to consider:
- Heart rate starts to rise at 20 weeks and increases until 32 weeks, remaining high 2–5 days after delivery 1
- A 30–50% increase in cardiac output occurs in normal pregnancy, with heart rate being the major factor in late pregnancy 1
- The immediate goal in managing heart failure during pregnancy is to decrease mean BP by 15–25% with the target to achieve SBP 140–150 mmHg and DBP 90–100 mmHg 1
Your doctor will likely check your blood pressure, perform blood tests to check for anemia or infection, and possibly do an electrocardiogram (ECG) to assess your heart's electrical activity. They may also monitor your baby with a non-stress test or ultrasound. You should contact your healthcare provider immediately or go to the emergency room for evaluation. While waiting for medical care, try to rest in a left side-lying position, stay hydrated, and take slow deep breaths. The elevated heart rate could potentially affect blood flow to your baby if sustained, which is why prompt evaluation is necessary. Never self-medicate for rapid heart rate during pregnancy as many medications can affect your baby.
From the Research
Fetal Heart Rate at 32 Weeks Pregnant
- A fetal heart rate (FHR) of 140 beats per minute (bpm) at 32 weeks pregnant falls within the normal range, as defined by international guidelines, which recommend a baseline FHR range of 110 to 150 bpm or 110 to 160 bpm 2.
- A study published in PeerJ in 2013 analyzed electronically recorded FHR tracings from singleton pregnancies and identified a "normal range" of 120 to 160 bpm, with FHR decreasing slightly during gestation 2.
- It is essential to note that FHR can vary depending on several factors, including gestational age and fetal activity.
Antepartum Fetal Surveillance
- Antepartum fetal surveillance methods, such as nonstress tests, contraction stress tests, and biophysical profiles, are used to evaluate fetal well-being in utero 3, 4, 5, 6.
- The biophysical profile, which assesses fetal movements, breathing movements, tone, and amniotic fluid volume, is considered a more accurate method for identifying hypoxic fetuses than single methods like nonstress tests or contraction stress tests 3, 6.
- A testing sequence of nonstress tests backed up by biophysical profiles and contraction stress tests can be used for antepartum fetal surveillance in high-risk pregnancies, such as those with insulin-requiring diabetes 5.