(598) Does antihypertensive therapy during pregnancy increase postpartum medication adherence for women with mild chronic hypertension?

The CHAP trial demonstrated that women randomized to antihypertensive therapy (vs. none) during pregnancy with mild chronic hypertension (cHTN) had better pregnancy outcomes. Our objective was to compare postpartum medication adherence at 6 weeks between the two groups. 

Study Design:

This study was a planned secondary analysis of a multicenter open-label RCT (The CHAP trial). Pregnant women with mild cHTN (Blood pressure; BP < 160/105 mmHg) were randomized to either antihypertensive therapy (Active) or no treatment (Control) unless severe hypertension (BP ≥160/105 mm Hg). The primary outcome was postpartum antihypertensive medication adherence, assessed by the medication adherence parameters (Table 1). The secondary outcome was BP control six weeks postpartum (BP < 140/90 mm Hg). Logistic regression models examined the association of antihypertensive therapy with outcomes. 

Results:

Of 2,408 CHAP participants, postpartum adherence was assessed for 1,684: 864 Active and 820 Control. Treatment groups were well-balanced for baseline characteristics, including age, race, BMI, and type of cHTN (Table 1). While postpartum antihypertensive prescription was higher in Active vs. Control (82% vs 58%, p< 0.0001), adherence measures did not differ (Table 2). Women in the Active group displayed a lower systolic BP (134.5 ± 14.9 vs. 136.1 ± 16.1 p< 0.05) than the Control group. Women in the Active group also displayed a greater BP control ( < 140/90 mmHg) at six-weeks postpartum (56.7% vs. 51.5%, p< 0.05, Table2).

Conclusion:

Antihypertensive therapy (vs. no treatment) of mild cHTN during pregnancy was associated with higher postpartum medication prescription but was not associated with postpartum medication adherence. The prevalence of adequate BP control at 6 weeks was higher in women in the Active group. Future studies should focus on whether antihypertensive treatment during pregnancy may contribute to postpartum and long-term maternal outcomes through attendant BP control.