A total of 461,966 women had a live singleton birth between 2004 and 2016 in SC. Of those, 430,545 were eligible for this investigation (59.2% NHW; 31.4% NHB, and 9.4% Hispanic) and were classified among the six exposure groups (see Table 1). These mutually exclusive groups consisted of women: (1) without pre-pregnancy HTN, HDP, or diabetes (77.6%); and with (2) diabetes (5.3%); (3) HDP (10.3%); (4) HDP and diabetes (1.6%); (5) HDP and pre-pregnancy HTN (3.9%); and (6) all three conditions (HDP, pre-pregnancy HTN, and diabetes; 1.2%). A total of 3,859 incident CHD events were recorded over the course of the up-to 14-year study (1,610 within 5 years of delivery), as well as 1,959 deaths (850 within 5 years of delivery).
Table 1 presents characteristics for the cohort overall and by exposure group. Compared to no conditions, women with diabetes regardless of HDP, with HDP and pre-pregnancy HTN, and with all three conditions were more likely to be older, NHB, have lower income, be eligible for Medicaid (except for those with HDP and diabetes), receive WIC during pregnancy, and have more pregnancies before the index birth (except for those with HDP). Women of all exposure groups were more likely to have a higher pre-pregnancy BMI than those with no conditions.
Pre-pregnancy HTN, HDP, and/or diabetes with incident CHD within 5 years and up to 14 years (entire study period) after delivery
Incident CHD event rates (per 1,000 person-years) within 5 years of delivery were highest for women with all three conditions (5.55, n = 123), followed by HDP and pre-pregnancy HTN (2.87, n = 211), HDP and diabetes (1.88, n = 57), HDP (1.22, n = 235), diabetes (1.11, n = 110), and no exposure (0.61, n = 874) (Supplemental Table 3). When examined by race/ethnic group for NHW and NHB women, incident CHD event rates within 5 years of delivery were highest for NHB women in all exposure groups (Fig. 2).
Incident CHD events (per 1,000 person-years) among women ≤ 5 years following delivery and over the entire study period (≤ 14 years) by race/ethnicity and exposure group a. CHD, coronary heart disease; CI, confidence interval; HDP, hypertensive disorders of pregnancy; HR, hazard ratio; HTN, hypertension (pre-pregnancy); NHB, non-Hispanic Black; NHW, non-Hispanic White. a The total population included Hispanic women; however, the number of events were too low to present race/ethnic-specific events for Hispanic women
Incident CHD event rates (per 1,000 person-years) within 14 years of delivery were also highest for women with all three conditions (6.75, n = 264), followed by HDP and pre-pregnancy HTN (3.65, n = 477), HDP and diabetes (2.81, n = 156), HDP (1.50, n = 529), diabetes (1.62, n = 295), and no exposure (0.79, n = 2138) (Supplemental Table 3). NHB women similarly experienced the highest CHD rates in all exposure groups within 14 years of delivery (Fig. 2).
Kaplan-Meier curves for maternal incident CHD within 5 years of delivery are presented with the y-axis truncated in Fig. 3. Incident CHD survival varied by exposure group for the total cohort and among NHB and NHW women, with survival lowest for those with all three conditions. There was no significant difference between women with diabetes only and women with HDP only. However, when comparing women with diabetes only to women with diabetes and HDP or to women with pre-pregnancy HTN, the groups were significantly different.
Maternal incident CHD survival within 5 years of delivery by populationa and exposure. CHD, coronary heart disease; HDP, hypertensive disorders of pregnancy; HTN, hypertension (pre-pregnancy). aTotal population includes Non-Hispanic White, Non-Hispanic Black, and Hispanic women. Hispanic-specific analysis was not run due to low counts
Model results for the risk of maternal incident CHD within 5 years of delivery and the entire study period are presented overall in Table 2 as there was not a significant interaction with racial/ethnic group. Model 1 adjusted for sociodemographic characteristics, model 2 further adjusted for behavioral characteristics, and model 3 further adjusted for clinical characteristics. After full adjustment, the risk of incident CHD within 5 years of delivery remained elevated for women with diabetes (HR = 1.57, 95% CI 1.28–1.92), HDP (HR = 1.85, 95% CI 1.60–2.15), HDP and diabetes (HR = 2.29, 95% CI 1.73–3.03), HDP and pre-pregnancy HTN (HR = 3.13, 95% CI 2.66–3.68), and all three conditions (HR = 4.87, 95% CI 3.95–6.01) compared to women with no conditions.
Within 14 years of delivery, the risk of incident CHD remained elevated for women with diabetes (HR = 1.65; 95% CI 1.46–1.88), HDP (HR = 1.68; 95% CI 1.53–1.86), HDP and diabetes (HR = 2.55; 95% CI 2.15–3.01), HDP and pre-pregnancy HTN (HR = 2.87; HR = 2.58–3.19), and all three conditions (HR = 4.51; 95% CI 3.92–5.18) compared to those with no conditions after full adjustment.
Pre-pregnancy HTN, HDP, and/or diabetes with all-cause mortality within 5 years and up to 14 years (entire study period) after delivery
All-cause mortality rates (per 1,000 person-years) within 5 years of delivery were highest among women with all three conditions (1.21, n = 27) followed by HDP and pre-pregnancy HTN (0.80, n = 59), HDP and diabetes (0.63, n = 19), HDP (0.50, n = 96), diabetes (0.56, n = 55), and no exposure (0.41, n = 594) (Supplemental Table 3). As for incident CHD, all-cause mortality rates within 5 years of delivery were highest for NHB women in each exposure group (Fig. 4).
All-cause mortality events (per 1,000 person-years) among women ≤ 5 years following delivery and over the entire study period (≤ 14 years) by race/ethnicity and exposure group a. CI, confidence interval; HDP, hypertensive disorders of pregnancy; HR, hazard ratio; HTN, hypertension (pre-pregnancy); NHB, non-Hispanic Black; NHW, non-Hispanic White. a The total population included Hispanic women; however, the number of events were too low to present race/ethnic-specific events for Hispanic women
All-cause mortality rates (per 1,000 person-years) within 14 years of delivery were highest among women with all three conditions (1.40, n = 56) followed by HDP and pre-pregnancy HTN (0.99, n = 134), HDP and diabetes (0.89, n = 50), diabetes (0.66, n = 120), HDP (0.61, n = 216), and no exposure (0.51 per 1,000 person-years, n = 1383) (Supplemental Table 3). As shown in Fig. 4, All-cause mortality rates within 14 years of delivery were highest for NHB women in each exposure group, although only slightly higher for those with HDP and diabetes or diabetes alone than NHW women.
Concerning all-cause mortality, women with all three conditions had the lowest survival rates (Fig. 5). Survival was also lowest for NHB women with all three conditions, whereas for NHW women, all-cause mortality survival appeared similar during the first two years after delivery, declining the most for women with all three conditions. There was no significant difference between women with diabetes only and women with HDP only or women with diabetes and HDP. However, there were significant differences when comparing women with diabetes only to women with pre-pregnancy HTN and HDP.
Maternal all-cause mortality within 5 years of delivery by populationa and exposure. HDP, hypertensive disorders of pregnancy; HTN, hypertension (pre-pregnancy). aTotal population includes Non-Hispanic White, Non-Hispanic Black, and Hispanic women. Hispanic-specific analysis was not run due to low counts
No significant interaction with race/ethnicity was found in the models built for the risk of maternal all-cause mortality within 5 years after delivery (Table 3). After full adjustment, all-cause mortality risk within 5 years remained elevated for women with diabetes (HR = 1.34; 95% CI 1.01–1.78), HDP and pre-pregnancy HTN (HR = 1.53; 95% CI 1.15–2.03), and all three conditions (HR = 2.25; 95% CI 1.51–3.36) compared to none, although was not significantly elevated for those with HDP or both HDP and diabetes.
Within 14 years of delivery, all-cause mortality risk was increased for women with diabetes (HR = 1.25; 95% CI 1.03–1.51), HDP and diabetes (HR = 1.62; 95% CI 1.22–2.15), HDP and pre-pregnancy HTN (HR = 1.56; HR = 1.30–1.89), and all three conditions (HR = 2.12; 95% CI 1.61–2.81) after full adjustment compared to those with no conditions (Table 3). The risk of all-cause mortality within 14 years of delivery was not statistically increased for women with HDP.