The Medicines Intelligence Data Platform: A Population-Based Data Resource From New South Wales, Australia.

BACKGROUND: The Medicines Intelligence (MedIntel) Data Platform is an anonymised linked data resource designed to generate real-world evidence on prescribed medicine use, effectiveness, safety, costs and cost-effectiveness in Australia. RESULTS: The platform comprises Medicare-eligible people who are ≥18 years and residing in New South Wales (NSW), Australia, any time during 2005-2020, with linked administrative data on dispensed prescription medicines (Pharmaceutical Benefits Scheme), health service use (Medicare Benefits Schedule), emergency department visits (NSW Emergency Department Data Collection), hospitalisations (NSW Admitted Patient Data Collection) plus death (National Death Index) and cancer registrations (NSW Cancer Registry). Data are currently available to 2022, with approval to update the cohort and data collections annually. The platform includes 7.4 million unique people across all years, covering 36.9% of the Australian adult population; the overall population increased from 4.8 M in 2005 to 6.0 M in 2020. As of 1 January 2019 (the last pre-pandemic year), the cohort had a mean age of 48.7 years (51.1% female), with most people (4.4 M, 74.7%) residing in a major city. In 2019, 4.4 M people (73.3%) were dispensed a medicine, 1.2 M (20.5%) were hospitalised, 5.3 M (89.4%) had a GP or specialist appointment, and 54 003 people died. Anti-infectives were the most prevalent medicines dispensed to the cohort in 2019 (43.1%), followed by nervous system (32.2%) and cardiovascular system medicines (30.2%). CONCLUSION: The MedIntel Data Platform creates opportunities for national and international research collaborations and enables us to address contemporary clinically- and policy-relevant research questions about quality use of medicines and health outcomes in Australia and globally.

Smoking Cessation Pharmacotherapy Use in Pregnancy.

Importance: Significant evidence gaps exist regarding the safety of smoking cessation pharmacotherapies during pregnancy, especially for the risk of congenital malformations. Consequently, professional bodies advise against the use of varenicline and bupropion and recommend caution with nicotine replacement therapy (NRT). Contemporary estimates of the use of smoking cessation pharmacotherapies during pregnancy are lacking. Objective: To quantify the proportion of individuals using prescribed smoking cessation pharmacotherapies during pregnancy and during the first trimester specifically, in 4 countries. Design, Setting, and Participants: This retrospective, population-based cohort study used linked birth records, hospital admission records, and dispensing records of prescribed medications from all pregnancies resulting in birth between 2015 and 2020 in New South Wales, Australia; New Zealand; Norway; and Sweden. Data analyses were conducted in October and November 2023. Exposure: Prescribed smoking cessation pharmacotherapy use (varenicline, NRT, and bupropion) during pregnancy was defined as days' supply overlapping the period from date of conception to childbirth. Main Outcomes and Measures: Prevalence of use among all pregnancies and pregnancies with maternal smoking were calculated. Among women who used a pharmacotherapy, the proportion of women with use during the first trimester of pregnancy was also calculated. Results: Among 1 700 638 pregnancies in 4 countries, 138 033 (8.1%) had maternal smoking and 729 498 (42.9%) were younger than 30 years. The prevalences ranged from 0.02% to 0.14% for varenicline, less than 0.01% to 1.86% for prescribed NRT, and less than 0.01% to 0.07% for bupropion. Among pregnant individuals who smoked, use of pharmacotherapies was up to 10 times higher, with maximum prevalences of 1.25% for varenicline in New South Wales, 11.39% for NRT in New Zealand, and 0.39% for bupropion in New Zealand. Use in the first trimester occurred among more than 90% of individuals using varenicline, approximately 60% among those using NRT, and 80% to 90% among those using bupropion. Conclusions and Relevance: In this cohort study of pregnant individuals in 4 high-income countries, the low prevalence of varenicline and bupropion use during pregnancy and higher prevalence of NRT use aligned with current clinical guidelines. As most use occurred in the first trimester, there is a need for evidence on the risk of congenital malformations for these medications.

Prevalence and Persistence of Prescription Opioid Use Following Hospital Discharge After Childbirth: An Australian Population-Based Cohort Study.

BACKGROUND: Opioid analgesics are used for acute postpartum pain relief but carry risks, including persistent long-term opioid use. Our primary objective was to estimate the prevalence of persistent use following hospital discharge after childbirth. METHODS: We conducted a population-based cohort study of women discharged from public or private hospitals in New South Wales, Australia, between 2012 and 2018 following vaginal birth (VB) or cesarean delivery (CD). We used linked hospitalization and medicine dispensing data to calculate the prevalence of opioid use within 14 days of hospital discharge for childbirth using an external estimate of the total number of hospital admissions for childbirth per year as the denominator. Among women dispensed an opioid postdischarge, we estimated the prevalence of persistent use defined as ≥3 dispensings between 30- and 365-days postdischarge. To calculate the odds of persistent opioid use, we performed a series of logistic regressions each including a single characteristic of interest. Included characteristics were maternal and birth characteristics, maternal medical conditions, prior use of certain medicines, and the initial opioid dispensed following discharge for childbirth. RESULTS: The final cohort comprised of 38,832 women who were dispensed an opioid in the 14 days following discharge after childbirth. Between 2012 and 2018, the prevalence of opioid use was increased following CD (public hospital 16.6%-21.0%; private hospital 9.8%-19.5%) compared with VB (public hospital 1.5%-1.5%; private hospital 1.2%-1.4%) and was higher following discharge from public hospitals compared with private. The most commonly dispensed opioids following discharge for childbirth were oxycodone (44.8%; 95% confidence interval [CI], 44.3-45.3), codeine (42.1%; 95% CI, 41.6-42.6), and tramadol (12.9%; 95% CI, 12.6-13.2). Among women dispensed an opioid, the prevalence of persistent opioid use was 5.4% (95% CI, 5.1-5.6). This prevalence was 11.4% (95% CI, 10.5-12.3) following a VB as compared with 4.3% (95% CI, 4.1-4.6) among those who underwent a CD ( P < .001). Characteristics associated with persistent opioid use included smoking during pregnancy, age <25 years, living in remote areas, discharged from a public hospital, history of opioid use disorder, other substance use disorder, mental health diagnosis, or prior use of prescription opioids, nonopioid analgesics, or benzodiazepines. CONCLUSIONS: The results of this cohort study indicate that Australian women have a higher prevalence of opioid use following CD compared to VB. One in 19 women dispensed an opioid postdischarge used opioids persistently. Careful monitoring of opioid therapy following childbirth is warranted, particularly among women with characteristics we identified as high risk for persistent opioid use.

High-dose folic acid and cancer risk; unjustified concerns by von Wrede and colleagues regarding our paper.

Women using antiseizure medication in pregnancy are often advised to use high doses of folic acid supplements (1mg to 5 mg) to reduce the risk of teratogenicity. Recently, we published a report showing an association between maternal prescription fill of high dose folic acid in relation to pregnancy and childhood cancer in the offspring. The report has sparked a debate about which dose of folic acid that should be recommended in pregnancy in women in need of antiseizure medication. In this Commentary, we explain our findings and the method used in our report, and answer recent questions that have emerged.

Association of In Utero Antipsychotic Medication Exposure With Risk of Congenital Malformations in Nordic Countries and the US.

Importance: Psychiatric disorders are common among female individuals of reproductive age. While antipsychotic medication use is increasing, the safety of such medications in pregnancy is an area with large evidence gaps. Objective: To evaluate the risk of first-trimester antipsychotic exposure with respect to congenital malformations, focusing on individual drugs and specific malformation subtypes. Design, Setting, and Participants: This cohort study used data from nationwide health registers from the 5 Nordic countries and the US and spanned 1996 to 2018. The Nordic cohort included all pregnancies resulting in singleton live-born infants, and the US cohort consisted of publicly insured mothers linked to their live-born infants nested in the nationwide Medicaid Analytic eXtract. Data were analyzed from November 2020 to April 2022. Exposures: One or more first-trimester dispensing of any atypical, any typical, and individual antipsychotic drugs. Main Outcomes and Measures: Any major congenital malformation and specific malformation subtypes previously suggested to be associated with antipsychotic exposure in utero: cardiovascular malformations, oral clefts, neural tube defects, hip dysplasia, limb reduction defects, anorectal atresia/stenosis, gastroschisis, hydrocephalus, other specific brain anomalies, and esophageal disorders. Propensity score stratification was used to control for potential confounders. Pooled adjusted estimates were calculated using indirect standardization. Results: A total of 6 455 324 unexposed mothers (mean maternal age range across countries: 24-31 years), 21 751 mothers exposed to atypical antipsychotic drugs (mean age range, 26-31 years), and 6371 mothers exposed to typical antipsychotic drugs (mean age range, 27-32 years) were included in the study cohort. Prevalence of any major malformation was 2.7% (95% CI, 2.7%-2.8%) in unexposed infants, 4.3% (95% CI, 4.1%-4.6%) in infants with atypical antipsychotic drug exposure, and 3.1% (95% CI, 2.7%-3.5%) in infants with typical antipsychotic drug exposure in utero. Among the most prevalent exposure-outcome combinations, adjusted relative risks (aRR) were generally close to the null. One exception was olanzapine exposure and oral cleft (aRR, 2.1 [95% CI, 1.1-4.3]); however, estimates varied across sensitivity analyses. Among moderately prevalent combinations, increased risks were observed for gastroschisis and other specific brain anomalies after atypical antipsychotic exposure (aRR, 1.5 [95% CI, 0.8-2.6] and 1.9 [95% CI, 1.1-3.0]) and for cardiac malformations after chlorprothixene exposure (aRR, 1.6 [95% CI, 1.0-2.7]). While the association direction was consistent across sensitivity analyses, confidence intervals were wide, prohibiting firm conclusions. Conclusions and Relevance: In this study, considering the evidence from primary and sensitivity analyses and inevitable statistical noise for very rare exposure-outcome combinations, in utero antipsychotic exposure generally was not meaningfully associated with an increased risk of malformations. The observed increased risks of oral clefts associated with olanzapine, gastroschisis, and other specific brain anomalies with atypical antipsychotics and cardiac malformations with chlorprothixene requires confirmation as evidence continues to accumulate.

Cancer Risk in Children of Mothers With Epilepsy and High-Dose Folic Acid Use During Pregnancy.

Importance: Women with epilepsy are recommended high doses of folic acid before and during pregnancy owing to risk of congenital anomalies associated with antiseizure medications. Whether prenatal exposure to high-dose folic acid is associated with increases in the risk of childhood cancer is unknown. Objective: To assess whether high-dose folic acid supplementation in mothers with epilepsy is associated with childhood cancer. Design, Setting, and Participants: Observational cohort study conducted with nationwide registers in Denmark, Norway, and Sweden from 1997 to 2017. Analyses were performed during January 10, 2022, to January 31, 2022. Mother-child pairs were identified in medical birth registers and linked with information from patient, prescription, and cancer registers, as well as with sociodemographic information from statistical agencies, and were categorized by maternal diagnosis of epilepsy. The study population consisted of 3 379 171 children after exclusion of 126 711 children because of stillbirth or missing or erroneous values on important covariates. Exposures: Maternal prescription fills for high-dose folic acid tablets (≥1 mg daily) between 90 days before pregnancy start and birth. Main Outcomes and Measures: First onset of childhood cancer at younger than 20 years. Cox proportional hazards models were used to calculate adjusted hazard ratios with corresponding 95% CIs, adjusted for potential confounders. Cumulative incidence at aged 20 years was used as a measure of absolute risk. Results: The median age at the end of follow-up in the study population of 3 379 171 children was 7.3 years (IQR, 3.5-10.9 years). Among the 27 784 children (51.4% male) born to mothers with epilepsy, 5934 (21.4%) were exposed to high-dose folic acid (mean dose, 4.3 mg), with 18 exposed cancer cases compared with 29 unexposed, producing an adjusted hazard ratio of 2.7 (95% CI, 1.2-6.3), absolute risk if exposed of 1.4% (95% CI, 0.5%-3.6%), and absolute risk if unexposed of 0.6% (95% CI, 0.3%-1.1%). In children of mothers without epilepsy, 46 646 (1.4%) were exposed to high-dose folic acid (mean dose, 2.9 mg), with 69 exposed and 4927 unexposed cancer cases and an adjusted hazard ratio of 1.1 (95% CI, 0.9-1.4; absolute risk, 0.4% [95% CI, 0.3%-0.5%]). There was no association between children born to mothers with epilepsy who were prenatally exposed to antiseizure medications, but not high-dose folic acid, and an increased risk of cancer (absolute risk, 0.6%; 95% CI, 0.2%-1.3%). Conclusions and Relevance: Prenatal exposure to high-dose folic acid was associated with increased risk of cancer in children of mothers with epilepsy.

Proton pump inhibitors and survival in patients with colorectal cancer: a Swedish population-based cohort study.

BACKGROUND: Proton pump inhibitors (PPIs) are associated with microbiome changes of the gut, which in turn may affect the progression of colorectal cancer (CRC). This study aims to assess the associations between PPI use and all-cause and CRC-specific mortality. METHODS: We selected all patients registered in the Swedish Prescribed Drug Registry who were diagnosed with CRC between 2006 and 2012 (N = 32,411, 54.9% PPI users) and subsequently followed them through register linkage to the Swedish Causes of Death Registry until December 2013. PPI users were patients with ≥1 post-diagnosis PPI dispensation. Time-dependent Cox-regression models were performed with PPI use as time-varying exposure. RESULTS: Overall 4746 (14.0%) patients died, with an aHR of 1.38 (95% CI 1.32-1.44) for all-cause mortality comparing PPI users with PPI nonusers. Higher-magnitude associations were observed among male, cancer stage 0-I, rectal cancer and patients receiving CRC surgery. The PPI-all-cause mortality association was also more pronounced comparing new users to non-users (aHR = 1.47, 95%CI 1.40-1.55) than comparing continuous users to non-users (aHR = 1.32, 95%CI 1.24-1.39). The risk estimates for CRC-specific mortality comparing PPI users to PPI nonusers were similar to those for all-cause mortality. CONCLUSION: PPI use after the CRC diagnosis was associated with increased all-cause and CRC-specific mortality.

Risk of squamous cell carcinoma of the lip and cutaneous melanoma in older Australians using hydrochlorothiazide: A population-based case-control study.

Recent European and US studies reported increased risks of skin cancers associated with hydrochlorothiazide (HCTZ) treatment. Our study aimed to determine the risk of lip cancer and malignant melanoma among Australians prescribed HCTZ. We conducted a case-control study nested within a population of veterans residing in New South Wales in 2004-2015, using Australian Department of Veterans' Affairs data linked with cancer registrations, hospitalisation and prescription dispensings. Among DVA healthcare card holders 65 years and older, we identified incident cases of squamous cell carcinoma of the lip and of cutaneous melanoma, each matched with up to 20 controls through risk-set sampling. We estimated odds ratios (ORs) associating HCTZ use with each cancer using conditional logistic regression, adjusting for predefined confounders. For lip cancer (45 cases), ever-use of HCTZ yielded an OR of 2.6 (95% CI: 1.4-5.0) and high HCTZ use (≥25 000 mg) an OR of 4.7 (95% CI: 1.6-13.7). For cutaneous melanoma (659 cases), ever-use of HCTZ resulted in an OR of 1.2 (95% CI 1.0-1.5) and high HCTZ use in an OR of 1.2 (95% CI: 0.8-1.8). Our findings align with risk estimates from previous studies and provide further evidence that HCTZ's photosensitising properties may promote carcinogenesis in sun-exposed tissues.

Use of proton pump inhibitors and mortality among Icelandic patients with prostate cancer.

Proton pump inhibitors (PPIs) are commonly used drugs among cancer patients. Due to conflicting reports on their safety, we aimed to determine whether PPI use is associated with mortality among prostate cancer patients. In this population-based cohort study, we identified incident diagnoses of prostate cancer between 2007 and 2012 (n = 1058). Follow-up was from 12 months after diagnosis until death, emigration or end the of study. Post-diagnosis use was defined as ≥2 filled prescriptions following diagnosis. We used time-dependent Cox proportional hazard regression models to compute hazard ratios (HRs) and 95% confidence intervals (CIs) for prostate cancer-specific and all-cause mortality associated with post-diagnosis use of PPIs. We identified 347 (32.8%) post-diagnosis PPI users and 711 (67.2%) non-users after diagnosis. Of the 347 patients using PPIs after diagnosis, 59 (17.0%) died due to any cause and 22 (6.3%) due to prostate cancer, compared with 144 (20.3%) and 76 (10.7%) among non-users after diagnosis, respectively. Post-diagnosis PPI use was not associated with prostate cancer-specific mortality (HR 0.88; 95% CI: 0.52-1.48) or all-cause mortality (HR 1.02; 95% CI: 0.73-1.43). Contrary to a previous report, this study did not find evidence of an association between post-diagnosis PPI use and mortality among prostate cancer patients.

Proton pump inhibitor use and risk of breast cancer, prostate cancer, and malignant melanoma: An Icelandic population-based case-control study.

PURPOSE: Increased expression of Vacuolar-type H+ ATPases (V-ATPases), in the plasma membrane of cancer cells has been suggested to contribute to the development of aggressive cancer phenotypes by promoting acidic tumor microenvironments. Accumulating data suggest that proton pump inhibitors (PPIs) may elicit a chemopreventive effect via V-ATPase inhibition in some cancers, but evidence is still limited. Therefore, we aimed to explore a potential preventive role of PPIs in this study. METHODS: In this population-based case-control study, we identified incident cases of breast cancer (n = 1739), prostate cancer (n = 1897), and malignant melanoma (n = 385) in Iceland between 2005 and 2014 from the Icelandic Cancer Registry. We assessed varying levels of PPI use through record linkages to the Icelandic Medicines Registry. For each case, we selected up to 10 age-matched, sex-matched, and calendar-matched population controls using risk-set sampling. Using conditional logistic regression, we calculated odds ratios (ORs) and 95% confidence intervals (CIs) controlling for NSAID use. RESULTS: Adjusted ORs associated with ever use of PPIs were 1.03 (95% CI: 0.92-1.16) for breast cancer, 1.12 (95% CI: 1.00-1.25) for prostate cancer, and 0.84 (95% CI: 0.69-1.12) for malignant melanoma. Analyses of high use of PPIs (≥1000 DDDs) yielded ORs of 0.97 (95% CI: 0.78-1.19), 1.20 (0.99-1.47), and 0.59 (0.40-1.13) for breast cancer, prostate cancer, and malignant melanoma, respectively. Analyses of cumulative exposure to PPIs did not support a dose-response relationship for any of the three cancer types. CONCLUSIONS: Our findings do not support a chemopreventive effect of PPI use on breast cancer, prostate cancer, or malignant melanoma.

Choosing wisely? Quantifying the extent of three low value psychotropic prescribing practices in Australia.

BACKGROUND: The global Choosing Wisely campaign has identified the following psychotropic prescribing as low-value (harmful or wasteful): (1) benzodiazepine use in the elderly, (2) antipsychotic use in dementia and (3) prescribing two or more antipsychotics concurrently. We aimed to quantify the extent of these prescribing practices in the Australian population. METHODS: We applied indicators to dispensing claims of a 10% random sample of Australian Pharmaceutical Benefits Scheme beneficiaries to quantify annual rates of each low-value practice from 2013 to 2016. We also assessed patient factors and direct medicine costs (extrapolated to the entire Australian population) associated with each practice in 2016. RESULTS: We observed little change in the rates of the three practices between 2013 and 2016. In 2016, 15.3% of people aged ≥65 years were prescribed a benzodiazepine, 0.5% were prescribed antipsychotics in the context of dementia and 0.2% of people aged ≥18 years received two or more antipsychotics concurrently. The likelihood of elderly people receiving benzodiazepines or antipsychotics in the context of dementia increased with age and the likelihood of receiving all three practices increased with comorbidity burden. In 2016, direct medicine costs to the government of all three practices combined, extrapolated to national figures, were > $21 million AUD. CONCLUSIONS: Our indicators suggest that the frequency of these three practices has not changed appreciably in recent years and that they incur significant costs. Worryingly, people with the greatest risk of harm from these prescribing practices are often the most likely to receive them.

Incidence of Crohn's Disease and Ulcerative Colitis in Rhode Island: Report from the Ocean State Crohn's and Colitis Area Registry.

BACKGROUND: Studies describing the incidence of Crohn's disease (CD) and ulcerative colitis (UC) are uncommon in the United States. We sought to determine the incidence of CD and UC in the state of Rhode Island. METHODS: The Ocean State Crohn's and Colitis Area Registry is a state-based inception cohort of patients newly diagnosed with inflammatory bowel disease (IBD) in Rhode Island. To confirm a diagnosis of CD, UC, or IBD unclassified (IBDU), the National Institute of Diabetes and Digestive and Kidney Diseases IBD Genetics Consortium criteria were applied in a review of medical records from gastroenterology practices located in the state of Rhode Island and adjacent to the Rhode Island border in Massachusetts and Connecticut. Using population-based data, we determined the statewide incidence of IBD in Rhode Island from 2008 to 2010. RESULTS: A total of 971 Rhode Island residents were diagnosed with IBD, including 444 with CD, 486 with UC, and 41 with IBD unclassified from 2008 to 2010. The overall age- and sex-adjusted IBD incidence was 30.2 (95% confidence interval, 28.3-32.1) per 100,000 persons in this time frame with 13.9, 15.1, and 1.3 per 100,000 diagnosed with CD, UC, and IBD unclassified, respectively. Of the total incident cases in Rhode Island, 30% (n = 291) were enrolled in Ocean State Crohn's and Colitis Area Registry for follow-up. CONCLUSIONS: The incidence of IBD in Rhode Island is higher than that previously reported by other population-based cohorts in the United States. Prospective follow-up of individuals enrolled in the community-based Ocean State Crohn's and Colitis Area Registry cohort is ongoing.

Deconstructing the smoking-preeclampsia paradox through a counterfactual framework.

Although smoking during pregnancy may lead to many adverse outcomes, numerous studies have reported a paradoxical inverse association between maternal cigarette smoking during pregnancy and preeclampsia. Using a counterfactual framework we aimed to explore the structure of this paradox as being a consequence of selection bias. Using a case-control study nested in the Icelandic Birth Registry (1309 women), we show how this selection bias can be explored and corrected for. Cases were defined as any case of pregnancy induced hypertension or preeclampsia occurring after 20 weeks' gestation and controls as normotensive mothers who gave birth in the same year. First, we used directed acyclic graphs to illustrate the common bias structure. Second, we used classical logistic regression and mediation analytic methods for dichotomous outcomes to explore the structure of the bias. Lastly, we performed both deterministic and probabilistic sensitivity analysis to estimate the amount of bias due to an uncontrolled confounder and corrected for it. The biased effect of smoking was estimated to reduce the odds of preeclampsia by 28 % (OR 0.72, 95 %CI 0.52, 0.99) and after stratification by gestational age at delivery (<37 vs. ≥37 gestation weeks) by 75 % (OR 0.25, 95 %CI 0.10, 0.68). In a mediation analysis, the natural indirect effect showed and OR > 1, revealing the structure of the paradox. The bias-adjusted estimation of the smoking effect on preeclampsia showed an OR of 1.22 (95 %CI 0.41, 6.53). The smoking-preeclampsia paradox appears to be an example of (1) selection bias most likely caused by studying cases prevalent at birth rather than all incident cases from conception in a pregnancy cohort, (2) omitting important confounders associated with both smoking and preeclampsia (preventing the outcome to develop) and (3) controlling for a collider (gestation weeks at delivery). Future studies need to consider these aspects when studying and interpreting the association between smoking and pregnancy outcomes.

Body Mass Index, Smoking and Hypertensive Disorders during Pregnancy: A Population Based Case-Control Study.

While obesity is an indicated risk factor for hypertensive disorders of pregnancy, smoking during pregnancy has been shown to be inversely associated with the development of preeclampsia and gestational hypertension. The purpose of this study was to investigate the combined effects of high body mass index and smoking on hypertensive disorders during pregnancy. This was a case-control study based on national registers, nested within all pregnancies in Iceland 1989-2004, resulting in birth at the Landspitali University Hospital. Cases (n = 500) were matched 1:2 with women without a hypertensive diagnosis who gave birth in the same year. Body mass index (kg/m2) was based on height and weight at 10-15 weeks of pregnancy. We used logistic regression models to calculate odds ratios and corresponding 95% confidence intervals as measures of association, adjusting for potential confounders and tested for additive and multiplicative interactions of body mass index and smoking. Women's body mass index during early pregnancy was positively associated with each hypertensive outcome. Compared with normal weight women, the multivariable adjusted odds ratio for any hypertensive disorder was 1.8 (95% confidence interval, 1.3-2.3) for overweight women and 3.1 (95% confidence interval, 2.2-4.3) for obese women. The odds ratio for any hypertensive disorder with obesity was 3.9 (95% confidence interval 1.8-8.6) among smokers and 3.0 (95% confidence interval 2.1-4.3) among non-smokers. The effect estimates for hypertensive disorders with high body mass index appeared more pronounced among smokers than non-smokers, although the observed difference was not statistically significant. Our findings may help elucidate the complicated interplay of these lifestyle-related factors with the hypertensive disorders during pregnancy.

Smoking and obesity among pregnant women in Iceland 2001-2010.

BACKGROUND: The prevalence of smoking during pregnancy in Western societies has decreased in the last decades, whereas prevalence of overweight and obesity has increased. Our objective was to study secular trends and patterns of smoking and body weight among pregnant women in Iceland, during a period of dramatic changes in the nation's economy. METHODS: On the basis of the Medical Birth Registry, we used a random sample of 1329 births between 1 January 2001 and 31 December 2010. Information on smoking, body mass index and background factors during pregnancy was retrieved from the Medical Birth Register and maternity records. Trends in smoking, overweight, obesity and body mass index were assessed using logistic and linear regression analyses. Logistic regression analysis was used to examine the annual odds of smoking and obesity and by socio-demographic characteristics. RESULTS: We found a decrease in the prevalence of continued smoking during pregnancy from 12.4% in 2001 to 7.9% in 2010 [odds ratio (OR) = 0.94, 95% confidence interval (CI) (0.88-1.00)], particularly among women with Icelandic citizenship [OR = 0.92, 95% CI (0.86-0.98)], whereas no changes in obesity [OR = 1.02, 95% CI (0.96-1.07)] were observed. The highest prevalence of maternal smoking and obesity was observed in 2005-06. CONCLUSION: Our results indicate that smoking during pregnancy decreased among Icelandic women in 2001-10, whereas an initial increase in obesity prevalence seemed to level off towards the end of the observation period. Interestingly, we found that both of these maternal risk factors reached their highest prevalence in 2005-06, which coincides with a flourishing period in the nation's economy.