Prenatal and Delivery Management to Reduce Adverse Pregnancy Outcomes Associated with Maternal Weight Public

Pickens, Cassandra M. Gibbs (2017)

Permanent URL: https://etd.library.emory.edu/concern/etds/4t64gn590?locale=fr
Published

Abstract

Pre-pregnancy obesity increases the risk of cesarean delivery, excess fetal growth, and maternal and infant morbidity. However, there is limited evidence on how to prevent adverse pregnancy outcomes among obese gravidas. Similarly to maternal pre-pregnancy weight, gestational weight gain (GWG) has important effects on perinatal health. However, little is known about the association between GWG and stillbirth. This dissertation explored ways to reduce the risk of adverse pregnancy outcomes associated with maternal weight. Aim 1 evaluated the association between GWG z-scores and stillbirth among 1,885 singleton deliveries in the Stillbirth Collaborative Research Network Case-Control Study. Gaining ≤35th percentile of GWG z-score increased the odds of stillbirth (adjusted odds ratio [aOR] for the 10th versus 50th percentile: 1.5 [95% Confidence Interval {CI} 1.3, 1.7]). Among overweight women, stillbirth odds were elevated for GWG z-scores ≥75th percentile. Aims 2 and 3 assessed whether term elective induction of labor (elective IOL, induction without indication) or expectant management (delivery in later weeks) was associated with lower odds of adverse pregnancy outcomes among obese women (Aim 2) and their offspring (Aim 3). The data source for Aims 2-3 was the 2007-2011 California Linked Patient Discharge Data/Birth Cohort file (N=219,360). Elective IOL between 37 and 40 weeks reduced the odds of cesarean delivery among obese women (aORs between 0.6 and 0.9). From 38-40 weeks' gestation, elective IOL reduced the odds of postpartum hemorrhage and severe maternal morbidity (aORs from 0.7-0.8). Elective IOL at 37 weeks was associated with increased infant mortality among obese parous women (aOR: 3.5 [95% CI 1.4, 8.5]). Term elective IOL was associated with reduced odds of macrosomia, infant hospital stay >5 days, meconium aspiration syndrome, chorioamnionitis, shoulder dystocia, and brachial plexus injury. This dissertation highlights possible ways to improve pregnancy outcomes among obese gravidas and their offspring. Gaining sufficient weight during pregnancy may reduce the risk of stillbirth among obese women; this was also true in normal weight and overweight women. Avoiding elective IOL <39 weeks' gestation may reduce the risk of infant mortality, while elective IOL between 39 and 41 weeks' gestation may decrease the risk of maternal and neonatal morbidity.

Table of Contents

Table Of Contents Chapter 1, Introduction and Specific Aims 1 Abbreviations in Dissertation 2 Background: Maternal Weight Before and During Pregnancy 4 Prevalence of Pre-Pregnancy Overweight and Obesity 4 Maternal and Infant Complications of Overweight and Obesity 5 Biological Plausibility: Maternal Overweight/Obesity 12 Complications of Maternal Underweight 16 Biological Plausibility: Maternal Underweight 17 Effects of Maternal Weight Gain During Pregnancy 17 GWG Patterns in Women of Different BMI Categories 21 GWG Interventions During Pregnancy 22 Dissertation Emphasis and Overview 23 Background: Aim 1 (GWG and Stillbirth) 24 Specific Aim (Aim 1 Overview) 24 Background and Significance 26 Biological Plausibility: GWG and Stillbirth 27 Evidence For an Association Between GWG and Stillbirth 28 Methodological Considerations 30 Aim 1 Summary and Next Steps 34 Background: Aims 2 and 3 (Elective Induction of Labor among Obese Women) 34 Specific Aims (Aims 2-3 Overview) 34 Background and Significance: Obstetric Management of Obese Women 38 Definition of Elective and Medically Indicated IOL 40 Secular Trends (and Policies) in Early Elective Delivery 42 Prior Research On IOL Versus Expectant Management 43 Chapter 2, Research Questions and Methods 49 Aim 1 Methods 50 SCRN Overview and Methods 50 Overview of The SCRN Case-Control Study 50 SCRN Study Design 52 SCRN Data Collection Instruments 53 Dissertation Aim 1 Methods 54 Aim 1 Data Sources And Exclusion Criteria 54 Exposure Measure 57 Statistical Methods 57 Ethics Approval 61 Aim 2 Methods 62 Aim 2 (And 3) Data Source 62 Ethics Approval 63 Aim 2 Study Exclusions 63 Exposure Definition 67 Study Outcomes 72 Statistical Analyses 72 Logistic Model for Dichotomous Outcomes 76 Sensitivity Analyses 77 Aim 3 Methods 79 Data Source, Study Exclusions, and Exposure Definition 80 Statistical Analysis 80 Sensitivity Analyses 81 Chapter 3, The Association Between Gestational Weight Gain Z-Score and Stillbirth: A Case-Control Study 82 Abstract 83 Introduction 85 Methods 86 Data Source 86 Exposure Measure 87 Statistical Analyses 88 Sensitivity Analyses 89 Results 90 Study Sample Characteristics 90 Association Between GWG Z-Score and Stillbirth 91 Additional Sensitivity Analyses 92 Comments 93 Conclusions 98 List Of Abbreviations 98 Declarations 98 Chapter 4, Term Elective Induction of Labor and Obstetric Outcomes among Obese Women 116 Abstract 117 Introduction 118 Materials and Methods 119 Data Source 119 Study Exclusion Criteria 120 Exposure Definition 120 Statistical Analysis 121 Sensitivity Analyses 122 Results 123 Discussion 125 Chapter 5, Term Elective Induction of Labor and Infant Outcomes among Obese Women 149 Abstract 150 Introduction 152 Materials and Methods 153 Statistical Analysis 154 Results 155 Comments 159 Acknowledgements 163 Chapter 6, Extended Analyses 186 Extended Analyses 1 and 2. Evaluating the Associations Between Total GWG and Stillbirth and Net GWG and Stillbirth Using SCRN Data 187 Background and Methodology 187 Results 189 Sensitivity Analyses 190 Comments 190 Extended Analysis 3. Assessment of Additive Interaction Between Elective IOL and Obesity Class in Studies of Maternal and Infant Outcomes (Aims 2 and 3 Extension) 199 Background and Methodology 199 Results 199 Comments 201 Extended Analysis 4. Use of Generalized Estimating Equations (GEE) in Studies of Elective IOL and Maternal and Infant Outcomes (Aims 2 and 3 Extension) 211 Background and Methodology 211 Results 211 Comments 212 Chapter 7, Implications and Conclusions 217 Aim 1 218 Aim 1 Implications 218 Aim 1 Limitations, Strengths, and Innovation 223 Aim 1 Conclusions 226 Aims 2 and 3 227 Aims 2-3 Implications 227 Aims 2-3 Limitations, Strengths, and Innovation 234 Aims 2-3 Conclusions 243 Summary 243 References 246

List of Tables/Figures

Chapter 2
  1. Figure 2-1. Aim 1 Study Exclusions by Case-Control Status (Page 56)
  2. Figure 2-2. Aims 2 and 3 Study Exclusion Criteria (Page 65)
  3. Table 2-1. Indications for Induction of Labor (Page 69)
Chapter 3
  1. Table 3-1. Frequencies of Maternal Characteristics by Case-Control Status (Pages 101-103)
  2. Table 3-2. Distributions of Total GWG and GWG Z-score by Case-Control Status (Page 104)
  3. Figure 3-1. Study Exclusions by Case-Control Status (Page 105)
  4. Figure 3-2. Association of Gestational Weight Gain Z-Score with Stillbirth (Page 106)
  5. Figure 3-3. Adjusted Odds Ratios for Gestational Weight Gain Z-score and Stillbirth by Pre-pregnancy BMI Category (Pages 107-108)
  6. Figure 3-4. Adjusted Odds Ratios for GWG Z-score and Stillbirth among Normal Weight Women using Fetal Growth Longitudinal Study (FGLS) Standards (Page 109)
  7. Figure 3-5. Adjusted Odds Ratios for GWG Z-score among Class 1 Obese and Morbidly Obese Women (Page 110)
  8. Supplementary Table 3-1. Unadjusted and Adjusted Odds Ratios for GWG Z-score among All Pre-pregnancy BMI Categories (Page 111)
  9. Supplementary Table 3-2. Unadjusted and Adjusted Odds Ratios for GWG Z-score among Normal Weight Women (Page 112)
  10. Supplementary Table 3-3. Unadjusted and Adjusted Odds Ratios for GWG Z-score among Overweight Women (Page 113)
  11. Supplementary Table 3-4. Unadjusted and Adjusted Odds Ratios for GWG Z-score among All Obese Women (Page 114)
  12. Supplementary Table 3-5. Adjusted Odds Ratios for GWG Z-score among Class 1 Obese and Morbidly Obese Women (Page 115)
Chapter 4
  1. Table 4-1. Frequencies of Maternal Characteristics among Electively Induced and Expectantly Managed Obese Women (Pages 130-132)
  2. Table 4-2. Distribution of Maternal Outcomes among Electively Induced and Expectantly Managed Obese Women (Pages 133-134)
  3. Figure 4-1. Study Exclusion Criteria (Pages 135-136)
  4. Figure 4-2. Adjusted Odds Ratios for Elective Induction of Labor (versus Expectant Management) and Obstetric Outcomes(Pages 137-138)
  5. Table 4-A1. Indications for Induction of Labor (Pages 139-141)
  6. Table 4-A2. Crude Odds Ratios for Elective Induction of Labor versus Expectant Management and Obstetric Outcomes (Page 142)
  7. Table 4-A3. Adjusted Odds Ratios for Elective Induction of Labor versus Expectant Management and Obstetric Outcomes (Pages 143-144)
  8. Table 4-A4. Adjusted Odds Ratios for Elective Labor Induction versus Expectant Management and Obstetric Outcomes, Accounting for Uncertain Timing of Intrapartum Indications (Pages 145-146)
  9. Table 4-A5. Adjusted Odds Ratios for Elective Labor Induction versus Expectant Management and Obstetric Outcomes using New Expectant Management Classification (Pages 147-148)
Chapter 5
  1. Table 5-1. Frequencies of Maternal Characteristics among Electively Induced and Expectantly Managed Obese Women, Stratified by Parity (Pages 164-167)
  2. Table 5-2. Distribution of Infant Outcomes among Electively Induced and Expectantly Managed Obese Women (Pages 168-169)
  3. Figure 5-1. Study Exclusion Criteria (Page 170)
  4. Figure 5-2. Adjusted Odds Ratios for Elective Labor Induction, as compared to Expectant Management, and Infant Mortality, Hospital Stay, Macrosomia, and Infection (Page 171-172)
  5. Figure 5-3. Adjusted Odds Ratios for Elective Labor Induction, as compared to Expectant Management, and Neonatal Morbidity (Pages 173-174)
  6. Table 5-S1. Indications for Induction of Labor (Pages 175-177)
  7. Table 5-S2. Crude Odds Ratios for Elective Induction of Labor versus Expectant Management and Infant Outcomes (Pages 178-179)
  8. Table 5-S3. Adjusted Odds Ratios for Elective Induction of Labor versus Expectant Management and Infant Outcomes (Pages 180-181)
  9. Table 5-S4. Adjusted Odds Ratios for Elective Labor Induction versus Expectant Management and Infant Outcomes, Accounting for Uncertain Timing of Intrapartum Indications (Pages 182-183)
  10. Table 5-S5. Adjusted Odds Ratios for Elective Labor Induction versus Expectant Management and Infant Outcomes using New Expectant Management Definition (Pages 184-185)

Chapter 6

  1. Table 6-1. Distributions of Total GWG and Net GWG by Case-Control Status (Page 194)
  2. Figure 6-1. Adjusted Associations of Total GWG and Net GWG with Stillbirth (Pages 195-196)
  3. Table 6-2. Unadjusted and Adjusted Odds Ratios for Total GWG and Stillbirth (Page 197)
  4. Table 6-3. Unadjusted and Adjusted Odds Ratios for Net GWG and Stillbirth (Page 198)
  5. Table 6-4. Assessment of Multiplicative and Additive Interaction between Elective IOL and Obesity Class for Maternal Outcomes (Pages 202-204)
  6. Table 6-5. Assessment of Additive Interaction between Elective IOL and Obesity Class for Ln(Maternal Postpartum Length of Stay) (Page 205)
  7. Table 6-6. Assessment of Multiplicative and Additive Interaction between Elective IOL and Obesity Class for Infant Outcomes (Pages 206-209)
  8. Table 6-7. Frequencies of Cesarean Delivery and Macrosomia by Obesity Class and Exposure Status (Page 210)
  9. Table 6-8. Adjusted Odds Ratios for Elective Labor Induction versus Expectant Management and Obstetric Outcomes, Accounting for Clustering by Delivery Hospital (Pages 213-214)
  10. Table 6-9. Adjusted Odds Ratios for Elective Labor Induction versus Expectant Management and Obstetric Outcomes, Accounting for Clustering by Delivery Hospital (Pages 215-216)

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