BACKGROUND AND PURPOSE:

• D’Souza et al. (Am. J. Obstet. Gynecol., 2019) sought to analyze pregnancy outcomes stratified by obesity classes (WHO classification system)

METHODS:

• Systematic review and meta-analysis
• Data sources
  • Medline, Embase, PubMed, www.clinicaltrials.gov, and Cochrane from inception to February 2019
  • Reference lists of included articles were searched
• Study inclusion criteria
  • Single-center and population-based cohort studies (no RCTs were identified)
  • Reported on pregnancy outcomes in women with BMI ≥30 kg/m2 stratified by Obesity Classes
• BMI categories for stratification
  • Normal weight (standard BMI): 18.5 to 24.9 kg/m2
  • Overweight (not obese): 25.0 to 29.9 kg/m2
  • Class 1 obesity: 30.0 to 34.9 kg/m2
  • Class 2 obesity: 35.0 to 39.9 kg/m2
  • Class 3 obesity: ≥40.0 kg/m2
• Study design and data analysis
  • Random-effects meta-analysis to determine
    • Pooled estimated and 95% confidence intervals for pregnancy outcomes in each BMI category
    • relative risk (RR) vs standard BMI

RESULTS:

• 13 studies | 3,722,477 pregnancies
• Risk of adverse outcomes vs standard BMI increased in a linear fashion as well as with each obesity class | Highest risks noted for Class 3

Perinatal Risks

• Maternal
  • GDM | Hypertensive disorders | Unplanned cesarean deliveries
• Infant
  • Prematurity | Stillbirth | Macrosomia | Birth trauma | RDS | Hypoglycemia | Early postnatal infection | NICU admission | Neonatal death

Highest Risk in Obesity Class 3

• Increased maternal risks
  • GDM: 17% vs 3.9% | RR 4.6 (95% CI, 3.6 to 5.9)
  • Hypertensive disorders of pregnancy: 15.9% vs 3.5% | RR 4.6 (95% CI, 3.4 to 6.0)
  • Cesarean delivery: 47.7% vs 26.0% | RR 1.86 (95% CI, 1.75 to 1.97)
• Increased newborn risks
  • Hypoglycemia: 4.1% vs 1.4% | RR 3.3 (95% CI, 2.8 to 3.8)
  • Macrosomia: 12.9% vs 6.2% | RR 2.6 (95% CI, 1.4 to 4.7)
  • Infection: 2.8% vs 1.3% | RR 2.3 (95% CI, 1.6 to 3.3)
  • Birth trauma: 1.3% vs 0.9% | RR 2.1 (95% CI, 1.2 to 3.8)
  • Respiratory distress: 5.1% vs 2.7% | RR 2.0 (95% CI, 1.8 to 2.2)
  • Death: 1.4% vs 0.9% | 1.8 (95% CI, 1.2 to 2.9)
  • NICU admission: 13.5% vs 9.5% | RR 1.6 (95% CI, 1.4 to 1.9)

CONCLUSION:

• The authors conclude that overall, “this study showed a linear association among almost all adverse pregnancy outcomes”
• The study includes tables for counseling stratified by obesity class that can potentially be used for counseling

Learn More – Primary Sources:

Maternal body mass index and pregnancy outcomes: a systematic review and metaanalysis

Related ObG Topics:

Maternal Overweight, Obesity and Congenital Malformations – How Strong is the Link?

Obesity in pregnancy – classification and clinical implications

Objective Data to Inform Weight Gain Recommendations for Pregnant Women with Obesity

Does Elective Induction Lower Risk for Adverse Obstetrical Outcomes in the Setting of Obesity