Dataset Information

Season of Conception, Smoking, and Preeclampsia in Norway.

ABSTRACT:

Background

Preeclampsia (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.

Methods

Seasonal 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.

Results

In 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.

Conclusions

These 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.

SUBMITTER: Weinberg CR

PROVIDER: S-EPMC5743488 | biostudies-literature | 2017 Jun

REPOSITORIES: biostudies-literature

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Publications

Season of Conception, Smoking, and Preeclampsia in Norway.

Weinberg Clarice R CR Shi Min M Basso Olga O DeRoo Lisa A LA Harmon Quaker Q Wilcox Allen J AJ Skjærven Rolv R

Environmental health perspectives 20170629 6

<h4>Background</h4>Preeclampsia (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.<h4>Methods</h4>Seasonal 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 pred ...[more]

PMID: 28669933

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Project description:IntroductionThe prevalence of congenital heart disease (CHD) among women of reproductive age is rising. We aimed to investigate the risk of preeclampsia and adverse neonatal outcomes in pregnancies of mothers with CHD compared to pregnancies of mothers without heart disease.Material and methodsIn a nationwide cohort of pregnancies in Norway 1994-2014, we retrieved information on maternal heart disease, the course of pregnancy, and neonatal outcomes from national registries. Comparing pregnancies with maternal CHD to pregnancies without maternal heart disease, we used Cox regression to estimate the adjusted hazard ratio (aHR) for preeclampsia and log-binomial regression to estimate the adjusted risk ratio (aRR) for adverse neonatal outcomes. The estimates were adjusted for maternal age and year of childbirth and presented with 95% confidence intervals (CIs).ResultsAmong 1 218 452 pregnancies, 2425 had mild maternal CHD, and 603 had moderate/severe CHD. Compared to pregnancies without maternal heart disease, the risk of preeclampsia was increased in pregnancies with mild and moderate/severe maternal CHD (aHR1.37, 95% CI 1.14-1.65 and aHR 1.62, 95% CI 1.13-2.32). The risk of preterm birth was increased in pregnancies with mild maternal CHD (aRR 1.33, 95% CI 1.15-1.54) and further increased with moderate/severe CHD (aRR 2.49, 95% CI 2.03-3.07). Maternal CHD was associated with elevated risks of both spontaneous and iatrogenic preterm birth. The risk of infants small-for-gestational-age was slightly increased with mild maternal CHD (aRR 1.12, 95% CI 1.00-1.26) and increased with moderate/severe CHD (aRR 1.63, 95% CI 1.36-1.95). The prevalence of stillbirth was 3.9 per 1000 pregnancies without maternal heart disease, 5.6 per 1000 with mild maternal CHD, and 6.8 per 1000 with moderate/severe maternal CHD. Still, there were too few cases to report a significant difference. There were no maternal deaths in women with CHD.ConclusionsModerate/severe maternal CHD in pregnancy was associated with increased risks of preeclampsia, preterm birth, and infants small-for-gestational-age. Mild maternal CHD was associated with less increased risks. For women with moderate/severe CHD, their risk of preeclampsia and adverse neonatal outcomes should be evaluated together with their cardiac risk in pregnancy, and follow-up in pregnancy should be ascertained.

Project description:We previously demonstrated that the frequency of birth defects among children of residents of the Red River Valley (RRV), Minnesota, USA, was significantly higher than in other major agricultural regions of the state during the years 1989-1991, with children born to male pesticide applicators having the highest risk. The present, smaller cross-sectional study of 695 families and 1,532 children, conducted during 1997-1998, provides a more detailed examination of reproductive health outcomes in farm families ascertained from parent-reported birth defects. In the present study, in the first year of life, the birth defect rate was 31.3 births per 1,000, with 83% of the total reported birth defects confirmed by medical records. Inclusion of children identified with birth or developmental disorders within the first 3 years of life and later led to a rate of 47.0 per 1,000 (72 children from 1,532 live births). Conceptions in spring resulted in significantly more children with birth defects than found in any other season (7.6 vs. 3.7%). Twelve families had more than one child with a birth defect (n = 28 children). Forty-two percent of the children from families with recurrent birth defects were conceived in spring, a significantly higher rate than that for any other season. Three families in the kinships defined contributed a first-degree relative other than a sibling with the same or similar birth defect, consistent with a Mendelian inheritance pattern. The remaining nine families did not follow a Mendelian inheritance pattern. The sex ratio of children with birth defects born to applicator families shows a male predominance (1.75 to 1) across specific pesticide class use and exposure categories exclusive of fungicides. In the fungicide exposure category, normal female births significantly exceed male births (1.25 to 1). Similarly, the proportion of male to female children with birth defects is significantly lower (0.57 to 1; p = 0.02). Adverse neurologic and neurobehavioral developmental effects clustered among the children born to applicators of the fumigant phosphine (odds ratio [OR] = 2.48; confidence interval [CI], 1.2-5.1). Use of the herbicide glyphosate yielded an OR of 3.6 (CI, 1.3-9.6) in the neurobehavioral category. Finally, these studies point out that (a) herbicides applied in the spring may be a factor in the birth defects observed and (b) fungicides can be a significant factor in the determination of sex of the children of the families of the RRV. Thus, two distinct classes of pesticides seem to have adverse effects on different reproductive outcomes. Biologically based confirmatory studies are needed.

Project description:IntroductionStandardised packaging on tobacco products was required in Norway July 1, 2018. We report pre-registered analyses of the potential impact on daily smoking and on daily snus use among women and men.MethodsInterrupted time series (segmented regression) on repeated cross-sectional surveys (2012-2019) from two sources: probability samples (Registry Sample, N = 46,957) and market research samples (Market Research Sample, N = 64,465) of Norwegian adults aged 16-79. Self-reported daily smoking and snus use were regressed on a step change impact variable, controlled for trend and demographics (sex, age, region, and education based on national registers in the Registry Sample, and self-reported in the Market Research Sample).ResultsThere were tendencies of a decline in smoking (Odds Ratio [OR] = 0.94; 95% confidence interval [CI] = 0.87, 1.02; lower-tail p-value [Plower] = 0.07), and women's snus use (OR = 0.89; CI = 0.77, 1.03; Plower = 0.06), but not men's snus use (OR = 1.01; CI = 0.92, 1.11; Plower = 0.59). Analyses using only the Registry Sample did not detect declines in smoking (OR = 0.99; CI = 0.88, 1.11; Plower = 0.43) or women's snus use (OR = 0.99; CI = 0.80, 1.24]; Plower = 0.48), and indicated no decline in men's snus use (OR = 1.18; CI = 1.03, 1.35; Plower = 0.99). Exploratory analyses suggested potential acceleration of the declining trend in smoking (change in trends, OR = 0.97) and of the increasing trend in men's snus use (OR = 1.03).ConclusionsThe analyses indicate that standardised packaging in Norway did not produce a decline in men's snus use. Results are inconclusive regarding smoking and women's snus use. Exploratory analyses indicated a decrease in smoking and an increase in men's snus use.ImplicationsWe could not confirm or disconfirm whether standardised packaging is an effective tobacco control measure in a Norwegian context. According to our analyses, standardized packaging may have effects on smoking prevalence and women's snus use, but is unlikely to reduce men's snus use. The present results may reflect higher effectiveness of standardised packaging for products with stronger health warnings. As the results varied according to samples and outcomes, the study underlines the importance of pre-registering future analyses on this topic. Future confirmatory research should test models of gradual impact of standardised packaging.

Dataset Information

Season of Conception, Smoking, and Preeclampsia in Norway.

Background

Methods

Results

Conclusions

Publications

Season of Conception, Smoking, and Preeclampsia in Norway.

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