What are normal vital signs during pregnancy?

From the Guidelines

Normal vital signs in pregnancy include a heart rate increase of 10-20 beats per minute, with resting rates of 80-100 beats per minute, a respiratory rate of 14-20 breaths per minute, and blood pressure that decreases by 10-15 mmHg by 20 weeks, but returns to pre-pregnancy levels by term, as indicated by the most recent study 1.

Key Vital Sign Changes

• Heart rate: increases by 10-20 beats per minute, particularly in the third trimester, with normal readings ranging from 80-100 beats per minute 1
• Respiratory rate: remains unchanged, with a normal range of 14-20 breaths per minute, and any rate above 20 breaths per minute may indicate a pathological cause 1
• Blood pressure: decreases by 10-15 mmHg by 20 weeks, but returns to pre-pregnancy levels by term, with normal readings around 110/70 mmHg in the first and second trimesters 1
• Oxygen saturation: remains unchanged throughout pregnancy, and should be above 95% 1
• Body temperature: remains unchanged throughout pregnancy, ranging from 97.8-99.5°F (36.5-37.5°C) 1

Importance of Monitoring

Regular monitoring of vital signs throughout pregnancy is crucial to distinguish between normal physiological changes and potential problems requiring intervention, such as preeclampsia, which can be indicated by elevated blood pressure (>140/90 mmHg) 1.

Additional Considerations

Healthcare providers should be aware of the potential for white-coat hypertension, and consider using home blood pressure monitoring or 24-hour ambulatory blood pressure monitoring to confirm diagnoses of hypertension 1.

Normal Ranges

Normal ranges for vital signs in pregnancy, as indicated by the most recent study 1, are:

• Heart rate: 80-100 beats per minute
• Respiratory rate: 14-20 breaths per minute
• Blood pressure: around 110/70 mmHg in the first and second trimesters
• Oxygen saturation: above 95%
• Body temperature: 97.8-99.5°F (36.5-37.5°C)

From the Research

Normal Vital Signs During Pregnancy

The normal vital signs during pregnancy can vary depending on the gestational age and other factors.

• Blood pressure:
  • Systolic blood pressure (SBP) and diastolic blood pressure (DBP) decrease slightly from 12 weeks of gestation, with median values of 114 mmHg and 70 mmHg, respectively, and then rise to a maximum median of 121 mmHg and 78 mmHg at 40 weeks of gestation 2.
  • Mean SBP and DBP for nulliparous women at 12 weeks gestation were 112.1 mmHg and 65.4 mmHg, and at 37 weeks were 116.0 mmHg and 70.0 mmHg, respectively 3.
• Heart rate:
  • The median heart rate was lowest at 12 weeks of gestation, with a value of 82 beats per minute (bpm), rising progressively to a maximum of 91 bpm at 34.1 weeks 2.
  • Mean heart rate rose from 79.3 bpm at 10 weeks to 86.9 bpm at 40 weeks gestation, with a mean change of 7.6 bpm 4.
• Oxygen saturation:
  • The median oxygen saturation (SpO2) decreased from 12 weeks of gestation, with a value of 98%, to 97% at 40 weeks 2.
• Respiratory rate:
  • The median respiratory rate at 12 weeks of gestation was 15 breaths per minute, which did not change with gestation 2.
• Temperature:
  • The median temperature at 12 weeks of gestation was 36.7°C, decreasing to a minimum of 36.5°C at 33.4 weeks 2.

Factors Affecting Vital Signs

Vital signs during pregnancy can be affected by various factors, including:

• Gestational age: Vital signs change throughout pregnancy, with some values decreasing and then increasing as gestation progresses 3, 2, 4.
• Maternal characteristics: Prepregnancy body mass index (BMI), smoking status, and parity can influence vital signs during pregnancy 3.
• Measurement methods: Manual and automated blood pressure measurements may yield different results, with manual measurements reporting higher diastolic blood pressures 4.