The Silent Emergency - Predicting Preterm Birth

Erdős Institute | Data Science Boot Camp Fall 2023

• View our 5-minute recorded presentation
• Download our Executive Summary

Team Members:

• Katherine Grillaert
• Divya Joshi
• Noah Rahman
• Alex Sutherland
• Kristina Zvolanek

Project Description

“The world is facing a silent emergency. . . of preterm births.” - UNICEF¹

Preterm birth is a primary cause of infant mortality and morbidity in the United States, affecting approximately 1 in 10 births.² This rate is notably higher among Black women (14.6%), compared to White (9.4%) and Hispanic women (10.1%).³ These rates have recently declined for White women but remained unchanged for other groups.⁴ Despite its prevalence, predicting preterm birth remains challenging due to its multifaceted etiology rooted in environmental, biological, genetic, and behavioral interactions.⁵ Our project harnesses machine learning techniques to predict preterm birth using electronic health records. This data intersects with social determinants of health, reflecting some of the interactions contributing to preterm birth.⁶ Recognizing that under-representation in healthcare research perpetuates racial and ethnic health disparities, we take care to use diverse data to ensure equitable model performance across underrepresented populations.⁷

Project Stakeholders

Pregnant individuals, prospective parents, medical professionals involved with maternal care and births, hospital systems, insurance companies

Approach

We constructed two models to predict preterm birth, one with demographic features and one with health and lifestyle features. Our data source was the National Institute of Health’s All of Us Research Program controlled tier of de-identified medical data. The Demographics model was trained on a dataset of 13690 births between the years 2009 and 2022. Most demographic information for each individual was available only as summary statistics based on their zip code. Race and ethnicity were available on the individual level. The Lifestyle model was trained on a dataset of 8771 births between the years 2011 and 2022. Features included drinking, smoking, drug use, body mass index, diabetes, and mental health.

Model Details

Baseline model: Our baseline model was a weighted coin flip that reflected the ratio of preterm births in our data.

Demographics model: The Demographics model was trained on a dataset of 13690 births between the years 2009 and 2022. Most demographic information for each individual was available only as summary statistics based on their zip code. Race and ethnicity were available on the individual level. We used a Support Vector Classifier with class weights to prioritize prediction of preterm birth. GridSearch CV was used to tune hyperparameters.

Lifestyle model: The Lifestyle model was trained on a dataset of 8771 births between the years 2011 and 2022. Features explored included drinking, smoking, drug use, body mass index, diabetes, and mental health. We used a logistic regression with class weights to prioritize prediction of preterm birth.

For both models, we used the package AI Fairness 360 to ensure that our model predictions performed equally well across protected classes (race and ethnicity).

Data Access

The data used to train these models was accessed from the All of Us Research Hub. You must register for the Researcher Workbench to access the data. We specifically used individual-level data from the Controlled Access Tier, which requires the completion of additional training. To facilitate testing without access to this protected health data, we have also provided a synthetic data frame.

Interacting with this Code

Dependencies

Running the code requires the following Python packages:

scikit-learn, pandas, numpy, matplotlib, aif360

Jupyter notebooks are organized into different folders:

Data Cleaning

In 01.Data_Cleaning we provide notebooks that extract relevant demographic or lifestyle data from All of Us and combine them into a single data frame.

• 01.Data_Cleaning/
  • Data_Cleaning_Demographics.ipynb
  • Data_Cleaning_Lifestyle.ipynb

Exploratory Data Analysis

In 02.Exploratory_Data_Analysis we provide notebooks that explore initial relationships between features via plots and summary statistics. Note: We also provide PDFs summarizing EDA outputs, so these results can be viewed without All of Us access.

• 02.Exploratory_Data_Analysis/
  • EDA_Demographics.ipynb
  • EDA_Lifestyle.ipynb

Applying the Models

Since the All of Us data is restricted, we provide two sets of models.

In 03.All_of_Us_Models, we provide the notebooks with the models we actually ran using the All of Us Data.

In 04.Demo_Models, we provide synthetic data frames for both the demographic and lifestyle models, so that the code can be run without the missing data.

• 03.All_of_Us_Models/

  • Preterm_Birth_Demographics_Models.ipynb
  • Preterm_Birth_Lifestyle_Models.ipynb

• 04.Demo_Models/

  • Demo_Preterm_Birth_Demographics_Models.ipynb
  • Demo_Preterm_Birth_Lifestyle_Models.ipynb
  • rawdemodataframe.ipynb
  • rawlifestyledataframe.ipynb

Model Workflows

Key Performance Indicators (KPIs) and Results

We prioritized minimizing costly false negatives, accepting the possibility of increased false positives. Therefore we chose Recall, F1, and Precision-Recall Area Under Curve (PR-AUC) as our key metrics. As we are concerned that our model performs equally well regardless of race or ethnicity, we chose the fairness metrics Equalized Odds and Statistical Parity Difference (SPD).

Demographic Model

Demographic Model	Final SVC	Baseline
Recall	0.413	0.145
F1	0.242	0.137
PR-AUC	0.172	0.192
Equalized Odds	0.0

Racial/Ethnic Group (privileged group: White)	SPD ‘Ground Truth’ Entire Dataset	SPD Test Predictions
Black or African American	-0.071	-0.065
Asian	0.003	0.000
Middle Eastern or North African	0.063	0.021
Native Hawaiian or Other Pacific Islander	0.003	-0.042
More than one	-0.047	-0.073
None of these	-0.004	0.041
No answer	-0.006	-0.007

Health and Lifestyle Model

Health and Lifestyle Model	Final Log	Baseline
Recall	0.473	0.137
F1	0.247	0.136
PR-AUC	0.197	0.196
Equalized Odds	0.0

Racial/Ethnic Group (privileged group: White)	SPD ‘Ground Truth’ Entire Dataset	SPD Test Predictions
Black or African American	-0.081	-0.103
Asian	-0.007	-0.053
Middle Eastern or North African	0.042	0.107
Native Hawaiian or Other Pacific Islander	-0.026	-0.226
More than one	-0.057	-0.026
None of these	-0.049	-0.179
No answer	-0.018	-0.032

Results

Our PR-AUC scores did not significantly outperform our baseline model, which was a weighted coin flip. Although higher recall scores were achievable, this came at the cost of precision due to a simple overprediction of the preterm birth class.

Our Equalized Odds scores indicate that our model demonstrated similar accuracy in predicting either preterm or term birth across protected classes of race and ethnicity, where the false positive rate and false negative rate are equal. Our Statistical Parity Difference (SPD) scores measure the difference in the preterm birth prediction rate between the test class and the privileged class. In our context, we consider White as the privileged class. SPD ranges from -1 to 1, and a score of 0 would imply perfect parity in preterm birth predictions between the test and privileged classes.

As expected, our model reflects but does not distort the disparities found in our dataset. An important caveat to these metrics: because our model is not reliably predicting preterm birth, the fairness metrics might not provide accurate insights or hold substantial value.

Conclusion and Future Work

Our models performed only as well as the baseline model, highlighting the challenges of predicting preterm birth with only electronic health records. Predictive models may need to incorporate features from more than one domain, including environmental, behavioral, biological, and genetic factors.⁶ Future work should consider the collection of thorough, individual-level data, observed during the pregnancy, in order to provide a high-quality data source for machine learning predictions.

Acknowledgements

Thank you to Evelyn Huszar for her enthusiastic mentorship during this project. Our gratitude also to Roman Holowinsky, Matt Osborne, Alec Clott, and The Erdős Institute for their support during this boot camp. Finally, thank you to the NIH and the All of Us program for collecting, anonymizing, and allowing us to use the data for this project.

The All of Us Research Program is supported by the National Institutes of Health, Office of the Director: Regional Medical Centers: 1 OT2 OD026549; 1 OT2 OD026554; 1 OT2 OD026557; 1 OT2 OD026556; 1 OT2 OD026550; 1 OT2 OD 026552; 1 OT2 OD026553; 1 OT2 OD026548; 1 OT2 OD026551; 1 OT2 OD026555; IAA : AOD 16037; Federally Qualified Health Centers: HHSN 263201600085U; Data and Research Center: 5 U2C OD023196; Biobank: 1 U24 OD023121; The Participant Center: U24 OD023176; Participant Technology Systems Center: 1 U24 OD023163; Communications and Engagement: 3 OT2 OD023205; 3 OT2 OD023206; and Community Partners: 1 OT2 OD025277; 3 OT2 OD025315; 1 OT2 OD025337; 1 OT2 OD025276. In addition, the All of Us Research Program would not be possible without the partnership of its participants.

References

1. World Health Organization et al. Born too soon: decade of action on preterm birth. World Health Organization, 2023.

2. Csaba Siffel, Andrew K Hirst, Sujata P Sarda, Michael W Kuzniewicz, and De-Kun Li. The clinical burden of extremely preterm birth in a large medical records database in the united states: Mortality and survival associated with selected complications. Early Human Development, 171:105613, 2022.

3. Preterm birth. https://www.cdc.gov/reproductivehealth/maternalinfanthealth/pretermbirth.htm, October 2023. Accessed: 2023-11-18.

4. Martin JA, Osterman M. Exploring the Decline in the Singleton Preterm Birth Rate in the United States, 2019-2020. NCHS Data Brief, (430):1-8, 2021.

5. Tracy A Manuck. Racial and ethnic differences in preterm birth: a complex, multifactorial problem. In Seminars in perinatology, volume 41, pages 511–518. Elsevier, 2017.

6. Dhelia M Williamson, Karon Abe, Christopher Bean, Cynthia Ferré, Zsakeba Henderson, and Eve Lackritz. Current research in preterm birth. Journal of Women’s Health, 17(10):1545–1549, 2008.

7. CM Vajdic, A Kricker, M Giblin, J McKenzie, J Aitken, GG Giles, and BK Armstrong. Reaching the hard-to-reach: a systematic review of strategies for improving health and medical research with socially disadvantaged groups. 2013.