RESULTS:
The primary analysis included a total of 4,022 pregnant individuals
(Figure 1). High allostatic load was identified in 33.0% (n=1327) of
individuals. Maternal age, race, gravidity, prior miscarriage, prior
bleeding at the first trimester, and insurance status were associated
with high allostatic load (Table 1)
The composite outcome was identified in 36.4% (n=1,462) individuals;
1079 (26.6%) had HTN, and 636 (15.4%) had MD. The time between index
pregnancy and HHS, maternal age, race, education, gravidity of 3 or
more, smoking status, and government health insurance were associated
with CVD outcomes, while other maternal characteristics were not (Tables
S1, S2, and S3). High allostatic load (OR= 2.1; 95% CI: 1.8-2.4) was
significantly associated with composite outcome. After adjustment for
the time between index pregnancy and HHS, maternal age, race, education,
smoking status, gravidity, smoking status, bleeding in the first
trimester, prior adverse pregnancy outcomes, and government health
insurance status, allostatic load remained significantly associated with
composite outcome (aOR 2.0, 1.8-2.3), (Table 2).
Associations persisted in the analysis of both components of composite
outcome. In bi-variable analysis, a high allostatic load was associated
with HTN (OR= 2.1; 95% CI: 1.8-2.4) and MD (OR= 1.9; 95% CI: 1.6-2.2).
In an adjusted model, HTN and MD remained significantly associated with
high allostatic load (aOR= 2.1; 95% CI: 1.8-2.4), and (aOR= 1.7; 95%
CI: 1.5-2.1), respectively. Results were similar in the sensitivity
analysis, where we included prior APOs: composite outcome (aOR = 1.9;
95% CI: 1.6-2.2), HTN (aOR = 1.9, 95% CI: 1.6-2.2), and MD (aOR = 1.8,
95% CI: 1.5-2.1) (Table 2).
In the exploratory analyses, the individual components of allostatic
load: BMI, DBP, SBP, triglycerides, HDL, creatinine, and CRP, were
significantly associated with composite outcome, HTN, and MD while
others were not. In addition, glucose was associated with composite
outcome and MD, LDL was associated with composite outcome, and HTN and
total cholesterol were associated with composite outcome (Table S4). In
a sensitivity analysis, an allostatic load score excluding both DBP and
SBP remained significantly associated with composite outcome (aOR = 1.9,
95% CI: 1.6-2.2), HTN (aOR = 1.7, 95% CI: 1.5-2.0). Similarly, an
allostatic load index excluding insulin remained significantly
associated with MD (aOR = 1.9, 95% CI: 1.6-2.3) (Table S7).
High allostatic load was a partial mediator in the association between
race and composite outcome, but not the individual components HTN or MD
(Table 3). In greater detail, first, we established a significant
association between race and composite outcome (path c, Table 3), race
and high allostatic load (path a, Table 3), and high allostatic load and
composite outcome (path b, Table 3). The magnitude of the relationship
between race and composite outcome in the presence of high allostatic
load was modestly smaller (path c’ vs. path c, Table 3). For composite
outcome components, HTN and MD, a significant association between race
and each outcome was present (path c). The association between race and
high allostatic load is significant (path a). The association between
allostatic load and each component of CVD outcomes was significant (path
b). However, we did not see a reduction in the magnitude of the
relationship between race and each component of the composite outcome
with the addition of high allostatic load. Thus, high allostatic load
was not demonstrated to mediate the association between race and HTN or
MD (Table 3). In a sensitivity mediation analysis where we restricted
the population to examine the association of allostatic load and CVD
between non-Hispanic Black and non-Hispanic White individuals, results
were similar in magnitude, significance, and interpretation (Table S5).
In the exploratory analysis testing whether race moderates the
relationship between allostatic load and composite outcome, the
association between allostatic load and CVD outcomes) was not
significantly different for non-Hispanic Black compared to
“Non-Hispanic White, Hispanic, Asian, Native American, Native Hawaiian,
multiracial and additional racial backgrounds”. The interaction test
(difference in the association of high allostatic load and CVD outcomes
by race) was not significant for any outcome in either unadjusted or
adjusted modeling. (Table 4), as such, race was not a significant
moderator of the relationship between allostatic load and composite
outcome. In a sensitivity moderation analysis where we restricted the
population to examine the difference in association of allostatic load
and CVD outcomes between non-Hispanic Black and non-Hispanic White
individuals, results were similar in magnitude, significance, and
interpretation (Table S6).