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178: Blood pressure patterns in pregnant women with treated chronic hypertension according to the development of severe preeclampsia

      Objective

      To examine blood pressure patterns across pregnancy in women with treated chronic hypertension according to the development of severe preeclampsia (SPE).

      Study Design

      This retrospective cohort study included women who required antihypertensive therapy during the first half of pregnancy. Management of these women includes titration of prenatal antihypertensive therapies in a coordinated fashion within a dedicated high-risk pregnancy clinic. Using a random effects model, predicted means of the mean arterial pressures (MAPs) were calculated from 5 to 40 weeks gestation for women with and without SPE with gestational age entered as a fourth order polynomial.

      Results

      Between January 2002 and December 2014, a total of 433 women met the inclusion criteria. Of these women, 67% (291/433) developed severe preeclampsia. The mean MAP was significantly higher at entry into prenatal care in women who were ultimately diagnosed with SPE in comparison those who were not (105.6 vs 101.7, p=0.002). The rate of change in MAP was similar in both the preeclamptic and non-preeclamptic cohorts until 24 weeks at which point the rates diverged significantly (p= 0.029) and continued to differ significantly until delivery. As shown in the Figure, women who developed SPE reached a blood pressure nadir at a significantly earlier gestational age than those who did not develop severe disease (25.9±7.1 vs 29.0±7.6, p <0.001).

      Conclusion

      Blood pressure patterns differ significantly in pregnant women with treated chronic hypertension who do and do not develop severe preeclampsia. The blood pressure nadir occurs approximately 3 weeks earlier in those who are destined to develop severe preeclampsia.
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