Ovarian Stimulation, Intrauterine Insemination, Multiple Pregnancy and Major Congenital Malformations: A Systematic Review and Meta- Analysis- The ART_Rev Study
Bibliographic record
Abstract
INTRODUCTION: Multiple pregnancies are a recognized adverse effect of assisted reproductive technologies; nevertheless, there is no consensus on the incremental risk associated with the ovarian stimulation (OS) used alone and intrauterine insemination (IUI). The relationship between OS and IUI and the risk of major congenital malformations (MCM) is unclear. OBJECTIVE: To summarise the literature and evaluate the risk of multiple pregnancy and MCM associated with OS used alone and IUI used with or without OS compared to natural conception (spontaneously conceived infants without any type of fertility treatments). METHODS: We carried out a systematic review to identify published papers between 1966 and 2014 in MEDLINE, EMBASE and the Cochrane Central Register of Controlled Trials. We included observational studies and randomized clinical trials related to the risk of multiple pregnancies and MCM conceived following OS alone or IUI compared to natural conception (spontaneously conceived infants without any fertility treatments). The quality of the included studies was evaluated using The Cochrane Collaboration's tool for assessing risk of bias for RCTs and the Newcastle-Ottawa Scale for observational studies. RESULTS: There were 63 studies included in this review. Our systematic review suggests that the use of any OS alone was associated with an increased risk of multiple pregnancy compared to natural conception (pooled RR 8.80, 95% CI 5.09- 15.20; p= 0.000; 9 studies). Similar increases in the risk of multiple pregnancies were observed following clomiphene citrate used without assisted reproductive technologies. Compared to natural conception, the use of IUI with or without OS was associated with an increased risk of multiple pregnancy (pooled RR 9.73, 95% CI 7.52 -12.60; p= 0.000; 6 studies). Compared to natural conception, the use of any OS alone was associated with an increased risk of any MCM (RR pooled 1.18, 95%CI 1.03-1.36; 11 studies), major musculoskeletal malformations (pooled RR 1.48, 95%CI 1.21-1.81; 7 studies), and malformations of the nervous system (pooled RR 1.73, 95%CI 1.15-2.61; 6 studies). Compared to natural conception, the use of IUI was associated with an increased risk of any MCM (pooled RR 1.23, 95%CI 1.10-1.37; 10 studies), major urogenital (pooled RR 1.52, 95%CI 1.04-2.22; 7 studies), and musculoskeletal malformations (pooled RR 1.54, 95%CI 1.20-1.98; 7 studies). The overall quality of the included studies was acceptable. CONCLUSIONS: The increased risk of multiple pregnancy and certain types of MCM associated with the use of less invasive fertility treatments, such as OS and IUI, found in this review, highlights the importance of the practice framing. Heterogeneity in OS protocols, the combination with other fertility agents, the limited number of studies and the methodological quality differences reduce our ability to draw conclusions on specific treatment. More observational studies, assessing the risk of multiple pregnancy or MCM, as a primary outcome, using standardized methodologies, in larger and better clinically defined populations are needed.
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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 | 0.009 | 0.027 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.016 | 0.026 |
| Bibliometrics | 0.006 | 0.008 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.003 | 0.002 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.005 | 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".