ArticleEnvironmental health perspectives2017
Season of Conception, Smoking, and Preeclampsia in Norway.
Article in Environmental health perspectives, 2017. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 12 papers, 2 of them syntheses that pooled it.
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
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Who cites it
12 citing papers in PubMed, 2 syntheses or guidelines pooled it.
- The Association Between Season and Hypertensive Disorders in Pregnancy: a Systematic Review and Meta-analysis.Reproductive sciences (Thousand Oaks, Calif.) · 2023Pooled it
- Fetal sex and maternal pregnancy outcomes: a systematic review and meta-analysis.Biology of sex differences · 2020Pooled it
- Aberrant Uteroplacental and Vascular Signaling and Remodeling by Matrix Metalloproteinases in Pregnancy-Related Hypertension and Preeclampsia.Biomolecules · 2026Review
- Comparison of the associations between office and home BP with placenta-mediated pregnancy complications: the BOSHI study.Hypertension research : official journal of the Japanese Society of Hypertension · 2026Article
- Association between embryo transfer season and the risks of hypertensive disorders of pregnancy and gestational diabetes mellitus.Journal of assisted reproduction and genetics · 2025Article
- Relative humidity, temperature, and hypertensive disorders of pregnancy: Findings from the Project Viva cohort.Environmental research · 2024Article
- Impact of Hypertensive Disorders of Pregnancy on the Risk of Stroke Stratified by Subtypes and Follow-Up Time.Stroke · 2022Article
- Maternal Levels of Perfluoroalkyl Substances (PFAS) during Early Pregnancy in Relation to Preeclampsia Subtypes and Biomarkers of Preeclampsia Risk.Environmental health perspectives · 2021Article
- Comparative risks and predictors of preeclamptic pregnancy in the Eastern, Western and developing world.Biochemical pharmacology · 2020Review
- Association between ambient temperature and hypertensive disorders in pregnancy in China.Nature communications · 2020Article
- Adverse Effects of Exposure to Fine Particulate Matters and Ozone on Gestational Hypertension.Current medical science · 2019Article
- Preeclampsia as a Form of Type 5 Cardiorenal Syndrome: An Underrecognized Entity in Women's Cardiovascular Health.Cardiorenal medicine · 2018Review
Corrections and comments
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Authors and funding
7 authors.
Funding
Abstract
backgroundPreeclampsia (PE) is a dangerous and unpredictable pregnancy complication. A seasonal pattern of risk would suggest that there are potentially preventable environmental contributors, but prior analyses have not adjusted for confounding by PE risk factors that are associated with season of conception.
methodsSeasonal effects were modeled and tested by representing each day of the year as an angle on a unit circle and using trigonometric functions of those angles in predictive models, using "harmonic analysis." We applied harmonic Cox regression to model confounder-adjusted effects of the estimated day of the year of conception on risk of PE for births from the Medical Birth Registry of Norway for deliveries between 1999 and 2009. We also examined effect measure modification by parity, latitude (region), fetal sex, and smoking.
resultsIn adjusted models, PE risk was related to season, with higher risk in spring conceptions and lower risk in autumn conceptions, with a risk amplitude (maximum compared with minimum) of about 20%. The pattern replicated across subpopulations defined by parity, latitude (region), fetal sex, and smoking.
conclusionsThese results suggest that there is a seasonal driver for PE, with effects that are not modified by parity, latitude, fetal sex, or smoking. https://doi.org/10.1289/EHP963.
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