Interpretation
Hypertensive disorders of pregnancy are associated with increased CVD
risk across multiple studies in diverse populations.(1,2) There is
compelling evidence that hypertension accounts for much of the CVD risk
following a hypertensive disorder of pregnancy, yet few interventions
have been studied to reduce progression to hypertension after a
hypertensive disorder of pregnancy.(27–29) Our previous work has
demonstrated that overweight and obese individuals have high rates of
ongoing hypertension at one-year postpartum and that overall individuals
may be particularly motivated to lower blood pressure following a
hypertensive disorder of pregnancy.(7)
Prior postpartum intervention studies have had high attrition rates,
which suggested that postpartum individuals may not be willing to
participate in intervention studies or engage in follow up care due to
the competing demands of the immediate postpartum period.(17,18) We
enrolled participants within the first six months postpartum and
retained almost 90% to one-year. Our study design was adapted to meet
institutional regulatory requirements in the setting of the COVID-19
pandemic, and a remote approach to recruitment and study visits may in
fact be well suited to this population. Before transitioning to a remote
approach, we offered individuals two options for the first study visit,
in-office study visit or a home visit. Among these early participants,
58% (n=26) opted for a home study visit, highlighting the potential
utility and desirability of this approach in the postpartum period as
well as the synergy of community partnering. Our overall enrollment
rates are in line with other studies of remote lifestyle interventions
for weight loss postpartum, but future work is warranted to understand
barriers to broaden enrollment of eligible participants. (30,31) Of the
individuals who declined to participate, reasons cited included that
being too busy or having the perception that their HDP “wasn’t that
bad” so they didn’t need an intervention. Future work should focus on
additional education and risk counseling in the postpartum period to
enhance understanding of future CV risk following a HDP. Additionally,
consideration of enhanced recruitment methods such as the use of social
media platforms or using technology to identify and recruit participants
and the use of community-based enrollment (e.g Women, Infants, Children
[WIC] or doula community programs) or integration with a clinical
postpartum visit may improve uptake of our intervention.
The parent Heart Health 4 Moms trial demonstrated improvement in
knowledge of CVD risk and self-efficacy to achieve a healthy diet and
decrease physical inactivity among predominantly white and highly
educated individuals within the first five years following a pregnancy
complicated by preeclampsia(8). The parent trial excluded individuals
with BP ≥140/90 mmHg, who were on anti-hypertensive agents or had a BMI
≥40 kg/m2. Compared to the initial trial, by design,
we enrolled a more diverse, higher-risk population, with 25% on
anti-hypertensive agents and 25% with a BP ≥140/90 mmHg at enrollment.
Importantly, we note that the majority of participants were able to come
off anti-hypertensive agents during the trial period.
Recent work has demonstrated that pharmaceutical interventions in the
immediate postpartum period may improve blood pressure and
cardiovascular function in the first year postpartum.(32,33) The SNAP-HT
trial randomized postpartum individuals who were on anti-hypertensive
agents following a hypertensive disorder of pregnancy to usual care with
in-office blood pressure assessments versus home blood pressure
monitoring plus management with systematic titration of
anti-hypertensive medications in the postpartum period. Cairns and
colleagues found that this approach was feasible and resulted in
improved diastolic blood pressure with a lowering of 4.5mmHg seen in the
intervention group up to 6 months postpartum.(33) Similarly, individuals
with preterm preeclampsia randomized to postpartum enalapril have
improved diastolic function and left ventricular remodeling at 6 months
postpartum when compared to individuals randomized to placebo.(32) These
studies suggest that the immediate postpartum period may be particularly
important for cardiovascular remodeling and that interventions in this
period may improve both short and long-term cardiovascular risk.
Despite promising data in the non-pregnant population, few studies have
investigated self-monitoring of BP combined with additional support. Our
study found a modest lowering of blood pressure in the intervention
arms. Given the evidence that modest BP elevations among young adults
(<40 years) are linked to significantly higher risk for
subsequent CV disease events when compared with those with normal BP,
modest BP improvements may be important.(34) Although our findings are
promising, the ongoing high rates of hypertension and need for
anti-hypertensive medication suggest the potential need for
interventions beyond home monitoring and lifestyle support in a
proportion of this population. Thus, postpartum monitoring may help
stratify groups for lifestyle versus more intensive follow-up to improve
BP control. Our findings support the need for larger studies with longer
follow up postpartum. One major limitation to interventions beyond the
immediate postpartum period is access to care. For individuals with
public health insurance, in many states within the United States,
Medicaid coverage lasts only through sixty days postpartum. The high
rates of ongoing hypertension in our population highlight the critical
need for Medicaid expansion to at least one year postpartum and the
importance of successful transitions of care postpartum from the
obstetrician to the primary care physician.
We saw no improvement in self-efficacy towards healthy diet and activity
or levels of physical activity and inactivity in the HH4NM + HBPM arm,
perhaps related to the high levels of self-efficacy at baseline. We also
saw no significant effect of our intervention on weight change. Prior
studies have shown that diet alone and diet paired with exercise after
delivery lead to greater weight loss compared to usual care in a general
postpartum population, not specifically in overweight or obese
individuals following a hypertensive disorder of pregnancy. A
meta-analysis of 7 trials demonstrated that diet combined with exercise
was significantly associated with postpartum weight loss with a mean
difference of 1.93 kg.(35) The dietary counseling in our intervention
was centered around implementing a DASH diet, as such, we note that
total daily sodium consumption, as measured by the Block Sodium Screener
decreased in the HH4NM + HBPM arm compared to the other two arms.
Consistent with a non-pregnant and
postpartum population, we found that higher sodium intake as assessed
with the Sodium Screener was associated with higher blood pressure and
that individuals with persistent hypertension at the conclusion of the
study reported higher sodium intake.(36–38) These findings support the
possibility of lower sodium intake leading to a greater reduction in
blood pressure in the intervention arm of our study and warrant further
investigation with more robust assessments such as urinary sodium
excretion. This could be relevant, as a recent study in individuals
approximately five years postpartum found that those with a history of
preeclampsia have an impaired ability to adapt their arterial stiffness
(as assessed by pulse wave velocity) in response to a change in sodium
intake when compared to those with a history of normal pregnancy.(39)