INTRODUCTION

Black women bear disproportionate morbidity and mortality from cardiovascular disease (CVD) and experience higher rates of adverse maternal outcomes than white women. Hypertension is a major contributor to these disparities in that black women have higher rates of hypertension and develop high blood pressure at a younger age. In addition, even before conception, hypertension leads to an increased risk of pregnancy complications as well as poorer long-term cardiovascular outcomes for mother and baby.1 Despite these potential transgenerational effects, hypertension among young women remains understudied and undertreated.

METHODS

Using data from NHANES (1999–2016), we examined the association between self-reported race/ethnicity and hypertension prevalence (defined as ≥140/90 mm Hg) among 4,255 (n=23,248,149 (weighted)) non-Hispanic black and white women (aged 18 to 35 years). We excluded women who (1) were missing race/ethnicity or blood pressure values; and (2) were pregnant at the time of the medical examination.

We used Student’s t and chi-square tests to characterize the study sample. We used a series of modified Poisson models with probability sampling weights to estimate the association of race with hypertension adjusting for age, marital status, income, educational attainment, insurance status, body mass index, smoking, drinking, diabetes status, stroke history, and birth control use. Stata 15 was used to perform statistical analyses (STATA 15).

RESULTS

Black and white women differed in terms of sociodemographic and health characteristics, except for age (Table 1). Notably, black women were less likely to smoke (76.0% versus 57.6% never smoked; p<0.0001) and to have ever used oral contraceptives (65.4% versus 11.4%; p<0.0001) compared to white women.

Table 1 Demographic, Health Behavior, and Health Status Characteristics of White and Black Women Aged 18 to 35 Years in the National Health and Nutrition Examination Surveys, 1999–2016

Black women exhibited higher mean BP (systolic: 113.9 versus 109.4 mmHg; p<0.0001; diastolic: 68.1 versus 67.0 mm Hg; p<0.01) and higher prevalence of hypertension (11.3% versus 3.4%; p<0.01). The overall prevalence in the study sample was 4.9%.

Table 2 compares the prevalence of hypertension (≥140/90 mm Hg) among young adult black and white women. In the unadjusted model, young black women demonstrated more than 3 times the prevalence of hypertension (PR: 3.4 95% CI: 2.6–4.3). In the fully adjusted model, including sociodemographic factors, health behaviors, and other health status factors, black women had 2.4 times the prevalence of hypertension (PR: 2.4 95% CI: 1.7–3.3).

Table 2 Association of Race with Hypertension Prevalence Among White and Black Women Aged 18 to 35 Years Old (Using JNC7 BP Outpoints) (N=4,238)

DISCUSSION

Our study examined racial differences in hypertension among black and white women in young adulthood. Although we found that young women generally have blood pressures well below treatment thresholds, black women had higher average blood pressures and were more than twice as likely to have hypertension adjusting for other sociodemographic and health factors. Findings suggest the need for primary prevention and disparities reduction by targeting this age group and young black women, in particular.

Compared to a previous study of reproductive-aged women,2 we found slightly lower race-specific prevalence estimates, but disparities of greater magnitude. This discrepancy may be due to the inclusion of older women in the previous study2—hypertension risk increases with age and health behaviors of young and middle-aged adults vary.3 Considering young women with respect to the stage of human development, including social and emotional components, rather than the broader biological categorization of “reproductive age,” may be the key to devising BP management approaches that promote sustained behavioral change and hypertension prevention.

Although this study was limited in its ability to account for it, higher chronic stress over the life course4 may help to explain higher BP among young black women. Preconception stress is an even stronger predictor of adverse outcomes than stress during pregnancy.5 Thus, the pre-conception period is not only an opportune time to promote preventive cardiovascular health strategies in young women for their current well-being, but to also interrupt psychological and physiological processes leading to poor cardiovascular and birth outcomes in the future.

While our study was based on a rigorous, nationwide sample, findings should be interpreted within the context of its limitations: (1) it is a cross-sectional analysis; and (2) average blood pressure was based on a single exam rather than repeated measures over time. Future studies should consider chronic stress in understanding the BP trajectory of young black women.