Effect of Maternal Age on the Risk of Stillbirth: A Population-Based Cohort Study on 37 Million Births in the United States
Bibliographic record
Abstract
The objective of our study was to evaluate the incidence and effect of maternal age on the risk of stillbirth. We conducted a population-based cohort study using the Centers for Disease Control and Prevention's "Linked Birth-Infant Death" and "Fetal Death" data files. We excluded all births of gestational age under 24 weeks and those with reported congenital malformations. We estimated the adjusted effect of maternal age on the risk of stillbirth using logistic regression analysis. There were 37,504,230 births that met study criteria, of which 130,353 (3.5/1,000) were stillbirths. Rates of stillbirth remained constant throughout the 10 years. As compared with women between the ages of 25 and 30, decreasing maternal age was associated with the following risk of stillbirth: odds ratio (OR) 0.95 (95% confidence interval [CI] 0.93 to 0.97) for ages 20 to 25; OR 0.97 (95% CI 0.94 to 0.99) for ages 15 to 20; and OR 1.32 (95% CI 1.18 to 1.47) for ages <15. Increasing maternal age was associated with an increasing risk of stillbirth: OR 1.02 (95% CI 0.99 to 1.04) for ages 30 to 35, OR 1.25 (95% CI 1.21 to 1.28) for ages 35 to 40, OR 1.60 (95% CI 1.53 to 1.67) for ages 40 to 45, and OR 2.22 (95% CI 1.91 to 2.53) for ages >45. Although the overall risk is low, the risk of stillbirth increases considerably in women at the extremes of the reproductive age spectrum. Antenatal surveillance may be justified in these women.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".