Severity of Congenital Heart Defects as a Predictor for Preterm Birth Open Access

Abstract

Purpose: 

To examine if preterm birth risk varies by congenital heart defect (CHD) severity.

Methods:

This study is a retrospective cohort design analyzing pregnant and non-pregnant female patients with CHD who were identified by encounters occurring between 1/1/2011-12/31/2013 in an existing Emory CHD surveillance repository. Women were linked to Georgia birth certificates during this time to examine the association between severity of CHD and preterm birth.

Results:

Among the initial cohort of 2,523 women aged 12-55, 1,525 (60.4%) had at least one pregnancy diagnosis code in their administrative record, but did not match to a birth certificate; 129 (5.1%) women matched to a birth certificate, but had no pregnancy diagnosis codes in their record; and 869 (34.4%) women had both pregnancy diagnosis codes and a matched birth certificate. After excluding women without a birth certificate match, without a pregnancy diagnosis code, or who only had a 745.5 code in isolation, we retained 823 women for further analyses. Overall, 23.9% (197/823) births were preterm and 43.4% (357/823) had a severe CHD. Both crude and adjusted analyses revealed that preterm birth was not significantly different for women who had a severe compared to those who had a not severe CHD.

Conclusion:

CHD severity may not be associated with preterm birth risk. However, failure to match a large segment of this sample with their birth outcomes may have biased the results towards the null. Further, a real difference in preterm birth risk may have been masked with differential misclassification of exposures because of issues with either the Marelli severity classification schema not sufficiently categorizing important CHD diagnoses for adverse pregnancy outcomes, or with administrative data using ICD-9-CM codes that comprise certain CCS categories that may not adequately differentiate obstetrical complications and comorbidities such as hypertension. To explore these hypotheses, integrated records are vital for patients with CHD, especially for women with CHD who are of reproductive age, to better manage their care and understand their risks during pregnancy.

Table of Contents

CHAPTER I: BACKGROUND ...................................................................................................... 1 

Introduction ................................................................................................................................ 1 

Congenital Heart Defects (CHD).................................................................................................. 1 

Types of CHD and Classification .................................................................................................. 2 

CHD and Pregnancy..................................................................................................................... 2 

Obstetric and Delivery Complications for Pregnant Women with CHD ..................................... 2 

Hypertensive Disorders for Pregnant Women with CHD ........................................................... 3 

Severe CHD and Pregnancy Complications ............................................................................. 4 

Not severe CHD and Pregnancy Complications .......................................................................... 9 

745.5 ......................................................................................................................................... 11 

Preterm Birth and Pregnant Women with CHD ........................................................................ 12 

Other Factors ............................................................................................................................ 13 

Maternal Age and Preterm Birth among Pregnant Women with CHD..................................... 13 

CHAPTER II: METHODS .......................................................................................................... 17 

Research Questions .................................................................................................................. 17 

Specific Aims ............................................................................................................................. 17 

Study Design.............................................................................................................................. 17 

Population ................................................................................................................................. 18 

Data Management and IRB ....................................................................................................... 18 

Inclusion and Exclusion Criteria ................................................................................................ 19 

Data Set Construction ............................................................................................................... 19 

Variables.................................................................................................................................... 20 

Directed Acyclic Graph (DAG) ................................................................................................... 23 

Statistical Analysis ..................................................................................................................... 24 

CHAPTER III: MANUSCRIPT ................................................................................................... 30 

Abstract ..................................................................................................................................... 30 

Introduction .............................................................................................................................. 31 

Study Design.............................................................................................................................. 32 

Population ................................................................................................................................. 32

Data Management and IRB ....................................................................................................... 33 

Exclusion Criteria....................................................................................................................... 33 

Predictor Variables .................................................................................................................... 33 

Statistical Analysis ..................................................................................................................... 34 

Results ....................................................................................................................................... 35 

Discussion.................................................................................................................................. 37 

Strengths and Limitations ......................................................................................................... 39 

Conclusion ................................................................................................................................. 40 

REFERENCES .......................................................................................................................... 41 

TABLES ................................................................................................................................... 48 

Table 1: Demographics for women* aged 12-55 years, who had at least one healthcare encounter with a congenital heart defect (CHD) diagnosis between 2011-2013 in Georgia, by whether they had a coded pregnancy diagnosis and a matched Georgia birth certificate (BC)................................................................................................................................................... 48 

Table 2a: Chi-square test for the association of CHD severity and select predictors by preterm birth status* for women^ who had at least one healthcare encounter with a CHD diagnosis between 2011-2013 in Georgia, and who had a coded pregnancy and a matched Georgia birth certificate (BC) .................................................................................................................. 50 

Table 2b: Chi-square test for association of preterm birth and select predictors by CHD severity* for women^ who had at least one healthcare encounter with a CHD diagnosis between 2011-2013 in Georgia, and who had a coded pregnancy and a matched Georgia birth certificate (BC) .................................................................................................................. 52 

Table 2c: Prevalence ratios and 95%CIs for the occurrence of CHD severity** and preterm birth* by select covariates for women^ who had at least one healthcare encounter with a CHD diagnosis between 2011-2013 in Georgia, and who had a coded pregnancy and a matched Georgia birth certificate (BC) ..................................................................................... 54 

Table 3. Crude and adjusted prevalence ratios and 95%CIs for the occurrence of preterm birth* by CHD severity** and select covariates among women^ who had at least one healthcare encounter with a CHD diagnosis between 2011-2013 in Georgia, and who had a coded pregnancy and a matched Georgia birth certificate (BC) .............................................. 56 

CHAPTER IV: EXTENDED ANALYSIS....................................................................................... 58 

Characteristics of the Cohort .................................................................................................... 58 

CHAPTER V: PUBLIC HEALTH IMPLICATIONS AND FUTURE TRENDS .................................... 61 

APPENDICES .......................................................................................................................... 65 

Appendix A ................................................................................................................................ 65 

Appendix B ................................................................................................................................ 67 

LITERATURE REVIEW TABLE .......................................................................................................... 78 

About this Master's Thesis

Rights statement

• Permission granted by the author to include this thesis or dissertation in this repository. All rights reserved by the author. Please contact the author for information regarding the reproduction and use of this thesis or dissertation.

School	Rollins School of Public Health
Department	Epidemiology
Subfield / Discipline	Epidemiology - MPH & MSPH
Degree	M.P.H.
Submission	Master's Thesis
Language	English
Research Field	Health Sciences, Public Health Health Sciences, Epidemiology
Keyword	congenital heart defect preterm birth
Committee Chair / Thesis Advisor	Carol J. Hogue, Emory University
Committee Members	Cheryl Raskind-Hood, Emory University

Last modified

Primary PDF

Thumbnail	Title	Date Uploaded	Actions
	Severity of Congenital Heart Defects as a Predictor for Preterm Birth ()	2019-04-24 14:18:20 -0400	Press to Select an action Download

Supplemental Files

Thumbnail	Title	Date Uploaded	Actions