The University of California Study of Outcomes in Mothers and Infants (a Population-Based Research Resource): Retrospective Cohort Study
Bibliographic record
Abstract
BACKGROUND: Population-based databases are valuable for perinatal research. The California Department of Health Care Access and Information (HCAI) created a linked birth file covering the years 1991 through 2012. This file includes birth and fetal death certificate records linked to the hospital discharge records of the birthing person and infant. In 2019, the University of California Study of Outcomes in Mothers and Infants received approval to create similar linked birth files for births from 2011 onward, with 2 years of overlapping birth files to allow for linkage comparison. OBJECTIVE: This paper aims to describe the University of California Study of Outcomes in Mothers and Infants linkage methodology, examine the linkage quality, and discuss the benefits and limitations of the approach. METHODS: Live birth and fetal death certificates were linked to hospital discharge records for California infants between 2005 and 2020. The linkage algorithm includes variables such as birth hospital and date of birth, and linked record selection is made based on a "link score." The complete file includes California Vital Statistics and HCAI hospital discharge records for the birthing person (1 y before delivery and 1 y after delivery) and infant (1 y after delivery). Linkage quality was assessed through a comparison of linked files and California Vital Statistics only. Comparisons were made to previous linked birth files created by the HCAI for 2011 and 2012. RESULTS: Of the 8,040,000 live births, 7,427,738 (92.38%) California Vital Statistics live birth records were linked to HCAI records for birthing people, 7,680,597 (95.53%) birth records were linked to HCAI records for the infant, and 7,285,346 (90.61%) California Vital Statistics birth records were linked to HCAI records for both the birthing person and the infant. The linkage rates were 92.44% (976,526/1,056,358) for Asian and 86.27% (28,601/33,151) for Hawaiian or Pacific Islander birthing people. Of the 44,212 fetal deaths, 33,355 (75.44%) had HCAI records linked to the birthing person. When assessing variables in both California Vital Statistics and hospital records, the percentage was greatest when using both sources: the rates of gestational diabetes were 4.52% (329,128/7,285,345) in the California Vital Statistics records, 8.2% (597,534/7,285,345) in the HCAI records, and 9.34% (680,757/7,285,345) when using both data sources. CONCLUSIONS: We demonstrate that the linkage strategy used for this data platform is similar in linkage rate and linkage quality to the previous linked birth files created by the HCAI. The linkage provides higher rates of crucial variables, such as diabetes, compared to birth certificate records alone, although selection bias from the linkage must be considered. This platform has been used independently to examine health outcomes, has been linked to environmental datasets and residential data, and has been used to obtain and examine maternal serum and newborn blood spots.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.005 |
| Meta-epidemiology (narrow) | 0.000 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.002 | 0.003 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".