A longitudinal study of contraception and pregnancies in the same women followed for a quarter of a century
Bibliographic record
Abstract
BACKGROUND: There is a need to improve our understanding of contraceptive use over the long term. The aims of this study were to describe contraceptive use and pregnancies in the same women followed prospectively from 19 to 44 years of age. METHODS: In 1981, a postal questionnaire about contraception, pregnancies and reproductive health was sent to a random sample (n = 656) of 19-year-old women resident in Gothenburg, Sweden. The responders were contacted again every fifth year. RESULTS: At 19 years of age, 74% of the women had already used contraception and this increased to 98% at 44 years. Combined oral contraception was the commonest method currently used up to 29 years of age (48/51/22% at 19/24/29 years of age, respectively) and thereafter an intrauterine device (IUD: 34/39/38% at 34/39/44 years of age, respectively). Condom use alone during the 25-year study period was: 14/12/24/21/21/15% and non-use of contraception was: 35/24/26/20/21/26%. The mean number of pregnancies/children increased from 0.2/0.1 at 19 years of age to 3.1/2.1 at 44 years. Women who had been pregnant and women who had not been pregnant <or=19 years of age were compared up to 44 years of age (months of OC use: 69/107, P < 0.01; months of IUD use: 126/91, P < 0.01; 4.2/2.9 pregnancies, P < 0.001; 2.5/2.1 children, P< 0.09). CONCLUSIONS: Choice of contraception was strongly related to age and parity, and the cumulative total number of pregnancies at 44 years of age, and contraceptive choice was related to age at first pregnancy.
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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 | 0.001 | 0.003 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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".