Adverse Pregnancy Outcomes
Definition
Adverse pregnancy outcomes (APOs) is a composite term encompassing four major pregnancy complications — hypertensive disorders of pregnancy (HDP: gestational hypertension and preeclampsia), preterm birth (<37 weeks), small-for-gestational-age (SGA) birth, and gestational diabetes mellitus (GDM) — that are associated with significant maternal morbidity and mortality, and with increased long-term cardiovascular risk in both the birthing individual and offspring. Approximately 1 in 5 births in the United States is complicated by at least one APO.
Key Facts
Epidemiology
- ~1 in 5 births in the US is complicated by an APO; rates have increased significantly over the past decade, with HDP rates nearly doubling sources/prepregnancy-aha-2023 (rating: high)
- CVD is the leading cause of pregnancy-related death, accounting for 26.5% of pregnancy-related deaths in the US sources/prepregnancy-aha-2023 (rating: high)
- Non-Hispanic Black individuals are significantly more likely to experience APOs; disparities are persistent and large across all four APO types sources/prepregnancy-aha-2023 (rating: high)
Types of APOs
Hypertensive Disorders of Pregnancy (HDP)
- Includes gestational hypertension, preeclampsia, eclampsia, and HELLP syndrome
- Strongly associated with prepregnancy obesity (PAF 26.5–30.3%), hypertension, and dyslipidemia
- Per 1 kg/m² inter-pregnancy BMI increase → OR 1.31 for HDP (meta-analysis) sources/prepregnancy-aha-2023 (rating: high)
- CHAP trial: treating mild chronic hypertension from early pregnancy reduced HDP, preterm birth, and SGA
Preterm Birth
- Birth <37 weeks gestation
- Associated with all individual prepregnancy CVH metrics
- Graded risk with cumulative poor CVH metrics: RR 1.15, 1.62, 2.85, 3.89 for 1, 2, 3, 4 poor CVH metrics respectively (vs no poor metrics) sources/prepregnancy-aha-2023 (rating: high)
- Preterm birth in offspring → 53% higher adjusted hazards for premature ischemic heart disease by age 43
Small-for-Gestational-Age (SGA) Birth
- Birth weight below the 10th percentile for gestational age
- Associated with placental malperfusion from vascular dysfunction
- Paradoxically increased after bariatric surgery pre-pregnancy (OR 2.18 despite improved HDP/GDM outcomes)
Gestational Diabetes Mellitus (GDM)
- Associated with prepregnancy glycemia across the spectrum, dietary patterns, fitness, sleep, and BMI
- Bariatric surgery pre-pregnancy reduces GDM risk (OR 0.21)
- History of GDM increases maternal risk of long-term T2DM and CVD
Relationship to Long-Term CVD
- APOs are associated with higher subsequent maternal CVD risk; APOs are considered a "window into future cardiovascular risk" (per AHA 2021 statement)
- APO survivors also at increased risk of long-term kidney disease, itself an important CVD risk factor
- Whether APOs are markers vs. mediators of the CVH–CVD relationship is unresolved sources/prepregnancy-aha-2023 (rating: high)
- APOs (HDP, preterm birth, GDM, SGA) are included in the 2018 multisociety guideline on management of blood cholesterol as CVD risk-enhancing conditions — all APO survivors warrant fourth-trimester follow-up with aggressive risk factor modification and future CVD risk counseling sources/cv-pregnancy-aha-2020 (rating: high)
HDP — quantified long-term CVD risk (independent of traditional risk factors):
- Hypertension: preeclampsia OR 11.6; onset 10 years earlier vs normotensive pregnancies sources/ht-pregnancy-aha-2022 (rating: high)
- Heart failure: HDP HR 2.7; preeclampsia aHR 2.1
- Coronary heart disease: preeclampsia aHR 2.1; HDP aHR 1.9
- Atrial fibrillation: preeclampsia aHR 1.7; HDP HR 1.4
- All stroke: preeclampsia aHR 1.9; HDP aHR 1.8
- Vascular dementia: preeclampsia aHR 2.4; gestational HT aHR 3.0
- CKD: preeclampsia RR 2.3; ESKD: preeclampsia RR 6.6
- ~2/3 of HDP-associated CVD risk is mediated by established risk factors; ~1/3 reflects HDP-specific pathogenesis sources/ht-pregnancy-aha-2022 (rating: high)
Pathophysiology
- Core mechanism: placental malperfusion secondary to inappropriate uterine spiral artery remodeling — begins long before clinical APO manifestations
- Prepregnancy CVD risk factors (obesity, hypertension, diabetes, dyslipidemia) affect placental development through angiogenesis and inflammatory pathways
- Periconceptional epigenetic reprogramming links maternal metabolic status to placental and embryonic gene expression — providing the mechanistic basis for a prepregnancy origin of APOs
- Markers of vascular dysfunction (↓arterial compliance, retinal microvascular constriction, diastolic dysfunction) in early pregnancy predict APO risk
Association with Offspring Cardiovascular Outcomes
- Preterm birth → 53% higher adjusted hazards for premature ischemic heart disease by age 43 in offspring sources/prepregnancy-aha-2023 (rating: high)
- Maternal prepregnancy T2DM → AHR 1.39 for offspring premature CVD by age 40
- Prepregnancy BMI more strongly associated with offspring CVD risk factors in adolescence than gestational weight gain
- Children of mothers who had prepregnancy lifestyle intervention had better LV structure/function at 6 years (small study, conflicting evidence)
Prevention Strategies
- Prepregnancy CVH optimization is the primary evidence-supported preventive strategy
- Treating pregestational hypertension from early pregnancy reduces HDP/preterm birth/SGA (CHAP trial)
- No large RCTs yet demonstrate that comprehensive prepregnancy CVH interventions reduce APO rates
- Postpartum transitional care clinics and lifestyle programs after APOs show promise for subsequent pregnancy risk reduction but are unevaluated for hard outcomes
Contradictions / Open Questions
- Causal vs. epiphenomenon: whether APOs are on the causal pathway CVH → APO → CVD or are epiphenomena of shared underlying risk remains unresolved; this distinction matters for intervention design sources/prepregnancy-aha-2023 (rating: high)
- APO reduction → long-term benefit: whether interventions that reduce APO frequency also improve long-term maternal and offspring CVD outcomes is unknown
- SGA paradox: bariatric surgery dramatically reduces HDP/GDM but increases SGA — suggesting competing mechanisms of benefit/harm in the same intervention
Connections
- Related to concepts/Prepregnancy-Cardiovascular-Health — poor prepregnancy CVH is the primary modifiable risk factor
- Related to concepts/Lifes-Essential-8 — CVH metrics that predict APO risk
- Related to concepts/Hypertensive-Disorders-of-Pregnancy — HDP is the APO most strongly linked to long-term CVD
- Related to concepts/Preeclampsia — the most severe HDP subtype driving long-term maternal CVD risk
- Related to entities/Maternal-Health-Disparities — APO rates disproportionately high in non-Hispanic Black women
- Related to entities/Heart-Failure — pregnancy-associated cardiomyopathy overlapping context
- Related to concepts/LQTS-Pregnancy-Management — specific maternal CVH context in inherited channelopathies
- Related to concepts/Cardio-Obstetrics — fourth-trimester follow-up for APO patients is a core cardio-obstetrics responsibility
- Related to entities/Peripartum-Cardiomyopathy — PPCM as an adverse cardiovascular event of pregnancy; preeclampsia aOR 3.3 for PPCM