BACKGROUND AND PURPOSE:

• Maternal age is increasing in developed countries
• Aoyama et al. (JAMA Netw. Open, 2019) examined the association between maternal age and severe maternal morbidity (SMM) as well as maternal death

METHODS:

• Nationwide population-based cohort study (2004 to 2015)
• Participants
  • All antepartum, peripartum, and postpartum women and adolescents seen at Canadian acute care hospitals
• Exposures
  • Maternal age at the index delivery
• Risk adjustment: Maternal Comorbidity Index used to adjust for differing baseline characteristics (only preexisting conditions included)
• ART data was not available for this study
• Primary outcomes (during pregnancy and within 6 weeks after termination of pregnancy)
  • Severe maternal morbidity | Maternal death

RESULTS:

• 3,162,303 pregnancies
  • Mean maternal age: 29.5 years
  • 3,533,259 related hospital admissions
• Severe maternal morbidity episodes: 17.7 cases per 1000 deliveries
  • 9.8% relative increase from 2004-2005 to 2014-2015
  • Increasing proportion of pregnancies were to older mothers
  • 2.4% events were antepartum period, including ectopic pregnancies
  • Most common causes: PPH | Sepsis | Cardiac failure  

Severe maternal morbidity: Independent patient-level factors

• Increasing Maternal Comorbidity Index
• Maternal age: ≤19 years or ≥30 years
• Greatest patient-level risk factors for severe morbidity
  • Maternal age ≥45 years vs 20 to 24 years: Odds ratio (OR) 2.69 (95% CI, 2.34 to 3.06)
  • Lowest income quintile vs highest income quintile: OR 1.19 (95% CI, 1.14 to 1.22)
• On subgroup analysis, parity did not alter the above findings

Maternal mortality: Independent patient-level factors

• Increasing Maternal Comorbidity Index
• Age 40 to 44 years vs 20-24 years: OR, 3.39 (95% CI, 1.68 to 6.82)
• Greatest patient-level risk factors for mortality
  • ≥45 years vs 20 to 24 years: OR 4.39 (95% CI, 1.01 to 19.10)
  • Lowest income quintile vs highest income quintile: OR, 4.14 (95% CI, 2.03 to 8.50)

Note: Hospital-level factors associated with maternal morbidity included province of residence and risk factors for mortality included lowest hospital pregnancy volume

CONCLUSION:

• Maternal age and severe maternal morbidity have increased over the past 10 years in Canada and authors note similar trends in the US (although lower rates for maternal mortality)
• This study supports comorbidities, income level and maternal age, especially ≥45 years, as independent risk factors for severe maternal morbidity and mortality
• The authors state

While not the most common causes of SMM, respiratory illness and cardiac illness are associated with a high risk of harm and death and should be an important focus for quality improvement initiatives, especially in older mothers (aged ≥35 years).

Learn More – Primary Sources:

Association of Maternal Age With Severe Maternal Morbidity and Mortality in Canada

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