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Meta-Analysis
. 2019 Sep 11;17(1):167.
doi: 10.1186/s12916-019-1399-1.

Trends of blood pressure and heart rate in normal pregnancies: a systematic review and meta-analysis

Lise Loerup  1 , Rebecca M Pullon  1 , Jacqueline Birks  2 , Susannah Fleming  3 , Lucy H Mackillop  4 , Stephen Gerry  2 , Peter J Watkinson  5
Affiliations
Meta-Analysis

Trends of blood pressure and heart rate in normal pregnancies: a systematic review and meta-analysis

Lise Loerup et al. BMC Med. .

Abstract

Background: Current reference ranges for blood pressure and heart rate throughout pregnancy have a poor evidence base.

Methods: This is a systematic review and meta-analysis. We included studies measuring blood pressure or heart rate from healthy pregnant women within defined gestational periods of 16 weeks or less. We analysed systolic blood pressure, diastolic blood pressure and heart rate by gestational age. We assessed effects of measurement year and method.

Results: We included 39 studies undertaken in 1967-2017, containing 124,349 systolic measurements from 36,239 women, 124,291 diastolic measurements from 36,181 women and 10,948 heart rate measurements from 8317 women. Mean (95% CI) systolic blood pressure was lowest at 10 weeks gestation, 110.4 (108.5, 112.3) mmHg, rising to 116.0 (113.6, 118.4) mmHg at 40 weeks, mean (95% CI) change 5.6 (4.0, 7.2) mmHg. Mean (95% CI) diastolic blood pressure was lowest at 21 weeks gestation, 65.9 (64.2, 67.7) mmHg; rising to 72.8 (71.0, 74.6) mmHg at 40 weeks, mean (95% CI) change 6.9 (6.2, 7.5) mmHg. Mean (95% CI) heart rate rose from 79.3 (75.5, 83.1) beats/min at 10 weeks to 86.9 (82.2, 91.6) beats/min at 40 weeks gestation, mean (95% CI) change 7.6 (1.8, 13.4) beats/min. Studies using manual measurement reported higher diastolic blood pressures than studies using automated measurement, mean (95 CI) difference 4.9 (0.8, 8.9) mmHg. Diastolic blood pressure increased by 0.26 (95% CI 0.10-0.43) mmHg/year. Including only higher-quality studies had little effect on findings, with heterogeneity remaining high (I2 statistic > 50%).

Conclusions: Significant gestational blood pressure and heart rate changes occur that should be taken into account when assessing pregnant women. Commonly taught substantial decreases in blood pressure mid-pregnancy were not seen and heart rate increases were lower than previously thought. Manual and automated blood pressure measurement cannot be used interchangeably. Increases in diastolic blood pressure over the last half-century and differences between published studies show contemporary data are required to define current normal ranges.

Study registration: PROSPERO CRD42014009673.

Keywords: Blood pressure (MeSH); Heart rate (MeSH); Maternal physiology; Pregnancy (MeSH); Vital signs (MeSH).

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Conflict of interest statement

PW, JB, SM and SF report significant grants from the National Institute of Health Research (NIHR), UK. PW, JB, SM, LM and SF report significant grants from the NIHR Biomedical Research Centre, Oxford, during the conduct of the study. PW and LM report modest grants and personal fees from Sensyne Health, outside the submitted work. LL and RP report significant grants from the RCUK Digital Economy Programme. LL reports significant grants from the Clarendon Fund. LL now works for the Boston Consulting Group, whose clients include medical technology and health analytics companies. PW and LM work part-time for Sensyne Health. PW and LM hold shares in Sensyne Health.

Figures

Fig. 1
Fig. 1
Study identification and selection
Fig. 2
Fig. 2
Mean BP (solid black line), with 95% CI (red band) by gestational age (longitudinal model). Trajectories of individual studies are also shown (thin lines)
Fig. 3
Fig. 3
Mean heart rate (solid black line), with 95% CI (red band) by gestational age (longitudinal model). Trajectories of individual studies are also shown (thin lines)
See this image and copyright information in PMC

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