Birth cohort effects on abdominal obesity in the United States: the Silent Generation, Baby Boomers and Generation X

The middle-aged and older Chinese adults' health using actigraphy in Taiwan (MOCHA-T): protocol for a multidimensional dataset of health and lifestyle

BACKGROUND AND OBJECTIVES

Older adults keep transforming with Baby Boomers and Gen Xers being the leading older population. Their lifestyle, however, is not well understood. The middle-aged and older Chinese adults' health using actigraphy in Taiwan (MOCHA-T) collected both objective and subjective data to depict the health and lifestyle of this population. The objectives, design, and measures of the MOCHA-T study are introduced, and the caveats and future directions related to the use of the data are presented.

METHODS

People aged 50 and over were recruited from the community, with a subset of women aged 45-49 invited to supplement data on menopause and aging. Four instruments (i.e., self-reported questionnaires, diary, wrist actigraphy recorder, and GPS) were used to collect measures of sociodemographic, health, psychosocial, behavioral, temporal, and spatial data.

RESULTS

A total of 242 participants who returned the informed consent and questionnaires were recruited in the MOCHA-T study. Among them, 94.6%, 95.0%, and 25.2% also completed the diary, actigraphy, and GPS data, respectively. There was almost no difference in sociodemographic characteristics between those with and without a completed diary, actigraphy, and GPS data, except for age group and educational level for those who returned completed actigraphy data.

CONCLUSION

The MOCHA-T study is a multidimensional dataset that allows researchers to describe the health, behaviors, and lifestyle patterns, and their interactions with the environment of the newer generation of middle-aged and older adults in Taiwan. It can be compared with other countries with actigraphy and GPS-based lifestyle data of middle-aged and older adults in the future.

Body mass index and waist circumference trajectories across the life course and birth cohorts, 1996-2015 Malaysia: sex and ethnicity matter

OBJECTIVE

The global obesity epidemic remains a significant threat to public health and the economy. Age-period-cohort (APC) analysis is one method to model the trajectory of obesity. However, there is scarce published evidence of such analyses among the South East Asian population. This study aims to explore the sex and ethnic variations of BMI and waist circumference trajectories over time among non-institutionalized Malaysian adults aged 18 to 80 years.

METHODS

Data from four population-based National Health and Morbidity Surveys conducted in 1996, 2006, 2010, and 2015 were pooled. Hierarchical Age-Period-Cohort (HAPC) analysis explored the trajectories of BMI and waist circumference across the life course and birth cohorts by sex and ethnicity. These models assumed no period effect.

RESULTS

Generally, BMI and waist circumference trajectories increased across age and birth cohorts. These trajectories varied by sex and ethnicity. Females have more profound increasing BMI and waist circumference trajectories than their male counterparts as they age and as cohort recency increases. Chinese have less profound BMI and waist circumference increases across the life course and birth cohorts than other ethnic groups.

CONCLUSIONS

The profound increasing cohort trajectories of obesity, regardless of sex and ethnicity, are alarming. Future studies should focus on identifying factors associated with the less profound cohort effect among the Chinese to reduce the magnitude of trajectories in obesity, particularly among future generations.

Early life socioeconomic position contributes to adult obesity independent of adult socioeconomic factors: Findings from the sister study cohort

Low socioeconomic position (SEP) has been associated with obesity within life stages; however, life course SEP may also alter downstream obesity risk. Research is needed to understand the impact of childhood SEP, independent of adult SEP, as well as SEP trajectories over the life course on adult obesity risk. We use data from the Sister Study, a prospective U.S. cohort of women aged 35-74 years (N = 50,884; enrollment: 2003-2009). Relative risks (RR) for adult obesity associated with childhood SEP (latent variable) and five latent life course SEP profiles were estimated in overall and race and ethnicity-stratified log binomial regression models. We estimated the direct effect of childhood SEP on adult obesity and mediation by adult SEP. Lower childhood SEP was associated with greater obesity risk (RR = 1.16, 95% CI: 1.15-1.17). In stratified models, RRs were elevated across groups though lower for Black and Hispanic/Latina participants, despite greater prevalence of obesity among Black participants. The direct effect of childhood SEP on adult obesity persisted in mediation models independent of adult SEP (RR = 1.10, 95% CI: 1.08-1.12) with adult SEP mediating approximately 40% of the total effect of childhood SEP on adult obesity. Furthermore, adult obesity risk was elevated for all life course SEP profiles compared to persistent high advantage. Life course SEP profiles indicating greater advantage in adulthood than childhood were not associated with reduced adult obesity risk among those experiencing less than high advantage in childhood. In conclusion, lower childhood SEP, independent of adult SEP, may be an important risk factor for adult obesity.

Health Benefits of a 16-Week Whole Food, High Fiber, Plant Predominant Diet among U.S. Employees

PURPOSE

To assess improvements in eating behaviors and health measures among adults participating in a whole food plant predominant diet, Full Plate Living (FPL) program.

DESIGN

Retrospective, post hoc analysis of self-reported 16-week pre-post participant data obtained over a 3 year program period (2017-19).

SETTING

Wellness offering for employees in Southwest U.S.

SUBJECTS

Of 6,820 enrollees, 4,477 completed the program, further segmented by generational cohorts.

INTERVENTION

FPL program materials and weekly online video lessons.

MEASURES

Baseline and follow-up measures included eating behaviors, self-perceived health status and energy, body weight, and confidence in healthy eating and weight loss.

ANALYSIS

Paired t-tests were used to examine changes in eating behaviors and health measures. Mixed-effects models were used to examine whether changes among generational cohorts differed.

RESULTS

Significant pre-post improvements were demonstrated for all measures, including servings of fruits (1.54 to 2.34), vegetables (2.05 to 2.87), beans (.63 to .99), and weight loss (3.5) (P < .001). Self-perceived health and energy values, and confidence in making healthy food choices and losing weight improved (P < .001). Improvements were observed across generational cohorts (P < .001).

CONCLUSION

The FPL healthy eating approach has a beneficial impact on health measures across generational cohorts, and may be an effective addition to lifestyle medicine and corporate wellness offerings. Longer-term program evaluation is warranted.

Memories of nursing in Singapore - an oral history approach

Background

Documentation of the voices of nurses provided valuable insight and a greater understanding of the nursing experience in Singapore.

Aim

To record nurses' experiences of journey of nursing profession in the acute care setting in Singapore from the early days of formalisation of nursing education to today's practice as a profession with various specialisation and career tracks.

Method

An oral history research approach was adopted, with purposive and snowball sampling to recruit nurses (both current and retired) who had trained in Singapore from 1956 which marked the beginning of the founding of the School of Nursing to current. Interviews were conducted with an interview guide. Thematic analysis was utilised to analyse the audio-recorded data.

Results

The 54 participants with a range of 10-54 years of nursing experience were interviewed and they completed their nursing training between 1952 and 2006. Four themes were generated: essence of nursing, inevitable changes across nursing profession, resilience and future outlook in nursing.

Conclusions

Understanding the experiences of these nurses generated an in-depth understanding of the personal, social and historical events that were at play in fostering today's nursing practice. With the evolution of the roles in nursing, compassion in current practice needs to be re-evaluated. Continuous learning is essential to meet the needs of the changing healthcare landscape.

The Contribution of Health Behaviors to Depression Risk Across Birth Cohorts

BACKGROUND

More recent birth cohorts are at a higher depression risk than cohorts born in the early 20th century. We aimed to investigate to what extent changes in alcohol consumption, smoking, physical activity, and obesity contribute to these birth cohort variations.

METHODS

We analyzed panel data from US adults born 1916-1966 enrolled in the Health and Retirement Study (N = 163,760 person-years). We performed a counterfactual decomposition analysis by combining age-period-cohort models with g-computation. We thereby compared the predicted probability of elevated depressive symptoms (CES-D 8 score ≥3) in the natural course to a counterfactual scenario where all birth cohorts had the health behaviors of the 1945 birth cohort. We stratified analyses by sex and race-ethnicity.

RESULTS

We estimated that depression risk of the 1916-1949 and 1950-1966 birth cohort would be on average 2.0% (-2.3 to -1.7) and 0.5% (-0.9 to -0.1) higher with the alcohol consumption levels of the 1945 cohort. In the counterfactual with the 1945 BMI distribution, depression risk is on average 2.1% (1.8 to 2.4) higher for the 1916-1940 cohorts and 1.8% (-2.2 to -1.5) lower for the 1950-1966 cohorts. We find no cohort variations in depression risk for smoking and physical activity. The contribution of alcohol is more pronounced for Whites than for other race-ethnicity groups, and the contribution of BMI more pronounced for women than for men.

CONCLUSION

Increased obesity levels were associated with exacerbated depression risk in recent birth cohorts in the United States, while drinking patterns only played a minor role.

Interspecific synchrony on breeding performance and the role of anthropogenic food subsidies

Synchrony can have important consequences for long-term metapopulations persistence, community dynamics and ecosystems functioning. While the causes and consequences of intra-specific synchrony on population size and demographic rates have received considerable attention only a few factors that may affect inter-specific synchrony have been described. We formulate the hypothesis that food subsidies can buffer the influence of environmental stochasticity on community dynamics, disrupting and masking originally synchronized systems. To illustrate this hypothesis, we assessed the consequences of European policies implementation affecting subsidy availability on the temporal synchrony of egg volume as a proxy of breeding investment in two sympatric marine top predators with differential subsidy use. We show how 7-year synchrony appears on egg volume fluctuations after subsidy cessation suggesting that food subsidies could disrupt interspecific synchrony. Moreover, cross correlation increased after subsidy cessation and environmental buffering seems to act during synchronization period. We emphasize that subsidies dynamics and waste management provide novel insights on the emergence of synchrony in natural populations.

Cohort Trends in the Burden of Multiple Chronic Conditions Among Aging U.S. Adults

OBJECTIVES

Multimorbidity, also referred to as multiple chronic conditions (MCCs), is the concurrent presence of 2 or more chronic health conditions. Increasing multimorbidity represents a substantial threat to the health of aging populations. Recent trends suggest greater risk of poor health and mortality among later-born cohorts, yet we are unaware of work examining cohort differences in multimorbidity among aging U.S. adults.

METHODS

We examine intercohort variation in MCC burden in adults aged 51 years and older using 20 years (n = 33,598; 1998-2018) of repeated assessment drawn from the Health and Retirement Study. The index of MCCs included 9 chronic conditions (heart disease, hypertension, stroke, diabetes, arthritis, lung disease, cancer excluding skin cancer, high depressive symptoms, and cognitive impairment). We used linear mixed models with various approaches to estimate age/period/cohort effects to model intercohort patterns in MCC burden. We also explored variation in the specific conditions driving cohort differences in multimorbidity.

RESULTS

More recent cohorts had greater MCC burden and developed multimorbidity at earlier ages than those born to prior generations. The burden of chronic conditions was patterned by life-course sociodemographic factors and childhood health for all cohorts. Among adults with multimorbidity, arthritis and hypertension were the most prevalent conditions for all cohorts, and there was evidence that high depressive symptoms and diabetes contributed to the observed cohort differences in multimorbidity risk.

DISCUSSION

Our results suggest increasing multimorbidity burden among more recently born cohorts of aging U.S. adults and should inform policy to address diminishing health in aging populations.

Age, Period, and Cohort Effects in Alcohol Use in the United States in the 20th and 21st Centuries: Implications for the Coming Decades

This article is part of a Festschrift commemorating the 50th anniversary of the National Institute on Alcohol Abuse and Alcoholism (NIAAA). Established in 1970, first as part of the National Institute of Mental Health and later as an independent institute of the National Institutes of Health, NIAAA today is the world's largest funding agency for alcohol research. In addition to its own intramural research program, NIAAA supports the entire spectrum of innovative basic, translational, and clinical research to advance the diagnosis, prevention, and treatment of alcohol use disorder and alcohol-related problems. To celebrate the anniversary, NIAAA hosted a 2-day symposium, "Alcohol Across the Lifespan: 50 Years of Evidence-Based Diagnosis, Prevention, and Treatment Research," devoted to key topics within the field of alcohol research. This article is based on Dr. Keyes' presentation at the event. NIAAA Director George F. Koob, Ph.D., serves as editor of the Festschrift.

Intergenerational Educational Attainment and Cardiometabolic Health in Latino Individuals Living in the United States

OBJECTIVE

This study aimed to estimate the association between cycles of poverty, measured by intergenerational educational attainment (IEA), and the burden of obesity and metabolic dysfunction among Hispanic/Latino individuals in the United States.

METHODS

This is a cross-sectional study utilizing data from 392 adults linked to 286 biologic parents from the Niños Lifestyle and Diabetes Study and the Sacramento Area Latino Study on Aging. The educational attainment of parents and offspring was dichotomized in order to categorize IEA. Outcomes included obesity and metabolic syndrome (MetS). Model-based standardization with population weights was used to compare obesity and MetS across generations, and Poisson regression was used to estimate prevalence ratios by IEA.

RESULTS

A higher prevalence of obesity and MetS was observed in offspring (54% and 69%, respectively) compared with their parents (48% and 42%, respectively). Compared with stable-low IEA, any category with high offspring education was associated with lower obesity and MetS prevalence. The upwardly mobile group saw the greatest benefit; they were 38% (95% CI: 10%-57%) and 46% (95% CI: 21%-63%) less likely to have obesity or MetS.

CONCLUSIONS

IEA strongly patterns cardiometabolic health among Hispanic/Latino individuals living in the United States, suggesting that promotion of higher education is associated with reductions in obesity and MetS, potentially benefitting future generations of this population.

Temporal Trends in Notification and Mortality of Tuberculosis in China, 2004-2019: A Joinpoint and Age-Period-Cohort Analysis

Tuberculosis (TB) remains a major public health problem in China and worldwide. In this article, we used a joinpoint regression model to calculate the average annual percent change (AAPC) of TB notification and mortality in China from 2004 to 2019. We also used an age–period–cohort (APC) model based on the intrinsic estimator (IE) method to simultaneously distinguish the age, period and cohort effects on TB notification and mortality in China. A statistically downward trend was observed in TB notification and mortality over the period, with AAPCs of −4.2% * (−4.9%, −3.4%) and −5.8% (−7.5%, −4.0%), respectively. A bimodal pattern of the age effect was observed, peaking in the young adult (aged 15–34) and elderly (aged 50–84) groups. More specifically, the TB notification risk populations were people aged 20–24 years and 70–74 years; the TB mortality risk population was adults over the age of 60. The period effect suggested that TB notification and mortality risks were nearly stable over the past 15 years. The cohort effect on both TB notification and mortality presented a continuously decreasing trend, and it was no longer a risk factor after 1978. All in all, the age effect should be paid more attention.

Obesity Trends and Associations with Types of Physical Activity and Sedentary Behavior in US Adults: National Health and Nutrition Examination Survey, 2007-2016

OBJECTIVE

Physical activity (PA) and sedentary behavior (SB) have been linked to adult adiposity. This research aims to explore 10-year (2007-2016) trends in obesity and abdominal obesity prevalence and associations with different types of PA and SB among US adults.

METHODS

National Health and Nutrition Examination Survey (NHANES) data were used with 20- to 64-year-old adults (n = 20,360; mean age: 41.9 years; male: 50.5%; non-Hispanic White: 64.3%). Sex- and sex- and race-specific linear trends in the prevalence of obesity, abdominal obesity, and moderate and vigorous work- and recreation-related PA and SB were estimated. Weighted logistic models explored the association between risk of obesity or abdominal obesity with each type of PA and SB by sex, adjusted for relevant confounders.

RESULTS

There were significant increasing trends in obesity and abdominal obesity in both sexes and in Hispanic adults. Men at higher vigorous work-related PA levels (P = 0.045) and women at higher moderate recreational-related PA (P = 0.005) levels had decreased risk of abdominal obesity. Women at the highest versus the lowest level of SB had increased risk of abdominal obesity (P = 0.017).

CONCLUSIONS

There was a significantly reduced risk for abdominal obesity with a few types of PA among both sexes and an increased risk with SB among women only.

Gender-specific temporal trends in overweight prevalence among Chinese adults: a hierarchical age-period-cohort analysis from 2008 to 2015

Background

As a key health risk, the prevalence of overweight has been strikingly increasing worldwide. This study aimed to disentangle the net age, period, and cohort effects on overweight among Chinese adults by gender.

Methods

Data came from the Chinese General Social Survey from 2008 to 2015, which was a repeated cross-sectional survey (n = 55,726, aged 18 and older). χ² or t tests were used to estimate the gender disparities in overweight and socioeconomic status (SES). A series of hierarchical age-period-cohort cross-classified random-effects models were performed using SAS version 9.4 to estimate the overall and gender-specific temporal trends of overweight, as well as the association between SES and overweight. Further, a series of line charts were used to present the age and cohort variations in overweight.

Results

After controlling for covariates, significant age and cohort effects were observed among adults in China (b = 0.0205, p < 0.001; b = 0.0122, p < 0.05; respectively). Specifically, inverted U-shaped age effects were identified for both genders, with a high probability of overweight occurring in middle age (b = -0.0012, p < 0.001). Overweight was more prevalent among men than women before 60 years old, and this trend reversed thereafter (b = -0.0253, p < 0.001). Moreover, men born during the war (before 1950) and reform cohorts (after the 1975s) demonstrated a substantial decline in overweight, while men born in 1950-1975 showed an increasing trend in overweight prevalence (b = 0.0378, p < 0.05). However, the cohort effect on women was not statistically significant. Additionally, a higher SES was related to an elevated probability of overweight.

Conclusion

Gender-specific age and cohort effects on the prevalence of overweight were observed among Chinese adults. Both China and other developing countries need to pay attention to the coming obesity challenge and related health inequality. Full life-cycle overweight prevention interventions should focus on middle-aged adults, men born in the war and reform eras, and adults with a higher SES.

The life-course association of birth-weight genes with self-rated health

This study examines the impact of genes associated with normal-range birth weight (2500-4500 grams) on self-rated health in mid-to-late life course. Fifty-eight previously identified genetic variants that explain the variation in the normal-range birth weight were used to construct a genetic measure of birth weight for the non-Hispanic white sample from the Health and Retirement Study. Our results show that the genetic tendency toward higher birth weight predicts better self-rated health in mid-to-late life course net of various demographic, socioeconomic, and health behavioral factors. We also examine the heterogeneous effects of birth-weight genes across birth cohorts and age groups. Moreover, to clarify the paradox that higher birth weight can predict both better self-rated health and higher BMI, we show the positive association between birth weight genes and BMI can only hold within the normal-range BMI (18 ≤ BMI < 30). Overall, these findings suggest the genetic factors underlying the normal-range birth weight can have life-courseimpacts on health.

Socially Active Aging and Self-Reported Health: Building a Sustainable Solidarity Ecosystem

Senior volunteering is associated with improved welfare, in addition to contributing to social development. Thus, the involvement of seniors in non-profit organizations (NPO), the third sector, or the social economy is encouraged by European national governments. At the organizational level, the situation for older volunteers in the third sector has improved in recent years, mainly due to European legal regulations. Despite a certain degree of homogenization across European countries, significant national differences persist in the adoption and promotion of volunteering. The present study examines the link between self-reported health and participation in volunteering activities among European seniors, stratified by sex and generation (the Silent Generation and the Baby Boomer Generation). We focus our analysis on seniors living in Germany, Poland, Romania, Russia, Slovenia, Spain, Sweden, Turkey, and Ukraine. Analyses were conducted using empirical micro data from the World Values Survey (WVS; 1994/98, 2005/09 and 2010/14). Our results demonstrate the positive impact of volunteering on health status among the elderly, although we observed marked differences in the associated benefits between sexes, generational cohorts, and countries. Public policies should be developed with this important source of social capital in mind, but should also seek to address existing inequity.

Recent increases in depressive symptoms among US adolescents: trends from 1991 to 2018

BACKGROUND

Mental health problems and mental health related mortality have increased among adolescents, particularly girls. These trends have implications for etiology and prevention and suggest new and emerging risk factors in need of attention. The present study estimated age, period, and cohort effects in depressive symptoms among US nationally representative samples of school attending adolescents from 1991 to 2018.

METHODS

Data are drawn from 1991 to 2018 Monitoring the Future yearly cross-sectional surveys of 8th, 10th, and 12th grade students (N = 1,260,159). Depressive symptoms measured with four questions that had consistent wording and data collection procedures across all 28 years. Age-period-cohort effects estimated using the hierarchical age-period-cohort models.

RESULTS

Among girls, depressive symptoms decreased from 1991 to 2011, then reversed course, peaking in 2018; these increases reflected primarily period effects, which compared to the mean of all periods showed a gradual increase starting in 2012 and peaked in 2018 (estimate = 1.15, p < 0.01). Cohort effects were minimal, indicating that increases are observed across all age groups. Among boys, trends were similar although the extent of the increase is less marked compared to girls; there was a declining cohort effect among recently born cohorts, suggesting that increases in depressive symptoms among boys are slower for younger boys compared to older boys in recent years. Trends were generally similar by race/ethnicity and parental education, with a positive cohort effect for Hispanic girls born 1999-2004.

CONCLUSIONS

Depressive symptoms are increasing among teens, especially among girls, consistent with increases in depression and suicide. Population variation in psychiatric disorder symptoms highlight the importance of current environmental determinants of psychiatric disorder risk, and provide evidence of emerging risk factors that may be shaping a new and concerning trend in adolescent mental health.

Prospective cohort studies of birth weight and risk of obesity, diabetes, and hypertension in adulthood among the Chinese population

BACKGROUND

Low birth weight (LBW) has been associated with subsequent risks of obesity and certain chronic diseases, but evidence for the associations is limited for the Chinese population.

METHODS

In this study we analyzed data from two population-based prospective cohort studies, the Shanghai Women's Health Study and the Shanghai Men's Health Study, to examine the associations between LBW and the risk of obesity and chronic diseases. Birth weight was self-reported at baseline; anthropometric measurements were made at study enrollment. Type 2 diabetes mellitus (T2DM) diagnoses were self-reported, whereas hypertension diagnoses were based on self-report and blood pressure measurements at baseline and follow-up surveys.

RESULTS

Birth weight was available for 11 515 men and 13 569 women. Non-linear associations were observed for birth weight with baseline body mass index (BMI), waist circumference (WC), waist:  hip ratio (WHR), and waist:  height ratio (WHtR; P < 0.05 for non-linearity), and LBW was linked with lower BMI, smaller WC, and larger WHR and WHtR. An excess risk of T2DM was observed for LBW (<2500 g) versus birth weight 2500-3499 g since baseline (hazard ratio [HR] 1.17; 95% confidence interval [CI] 0.92-1.49) and since birth (HR 1.29; 95% CI 1.07-1.54), whereas the HRs for hypertension since baseline and birth were 1.13 (95% CI 1.01-1.27) and 1.20 (95% CI 1.11-1.30), respectively. The risk of the diseases decreased as birth weight increased up to ~4000 g; further increases in birth weight did not convey additional benefits.

CONCLUSION

The results suggest that LBW, an index of poor intrauterine nutrition, may affect health risks later in life in the Chinese population.

Epidemiology of Obesity in Adults: Latest Trends

PURPOSE OF REVIEW

An increasing trend in obesity prevalence since the early 1980s has posed a significant population health burden across the globe. We conducted a systematic review for studies using measured anthropometry to examine trends in obesity in the USA published from 2012 to 2018 and for systematic reviews to document trends in obesity across the globe published from 2014 to 2018.

RECENT FINDINGS

For the USA, the only nationally representative data source capturing trends in obesity in this period was the National Health and Nutrition Examination Survey, which uses repeated cross-sectional data to document national trends in obesity in the USA. For global trends, the only systematic reviews of obesity across the globe were the Global Burden of Disease Obesity study and the Non-communicable Disease Risk Factor Collaboration study. In general, the population distribution of body mass index (BMI) in the USA has shifted towards the upper end of its distribution over the past three decades. The global distribution has similarly increased, albeit with large regional differences. US and global studies suggest an increasing trend in obesity since the 1980s, and there is a dearth of nationally representative longitudinal studies using measured anthropometry to capture trends in adult obesity in the USA for the same individuals over time. Greater efforts are needed to identify factors contributing to the continued increases in obesity.

Cohort Contributions to Race- and Gender-Specific Trends in the Incidence of Hepatocellular Carcinoma in the USA

INTRODUCTION

Increasing incidence of lifelong obesity and associated nonalcoholic steatohepatitis in younger birth cohorts may have contributed to growing incidence of hepatocellular carcinoma (HCC) in the USA. Yet, the contribution of cohort effects to trends in HCC incidence is unclear.

METHODS

Using data from the Surveillance, Epidemiology, and End Results (SEER) program 1973-2013, race- and gender-specific trends in HCC incidence in the USA were decomposed using age-period-cohort (APC) modeling.

RESULTS

Among SEER registry sites included in the analysis, there were 25,532 cases of HCC diagnosed including 15,867 (62%) White males, 3541 (14%) Black males, 5009 (20%) White females, and 1115 (4%) Black females. HCC incidence increases across periods, especially among men. Underlying this increase, APC models found significant cohort effects among White men, White women, and Black men, with rapid growth in HCC risk among cohorts born after 1940. A similar cohort trend among Black women did not reach statistical significance when compared to an age-period model.

CONCLUSIONS

Cohort-specific trends have significantly contributed to increasing HCC incidence in recent decades. The rapid increase in HCC risk among younger cohorts suggests that the incidence of HCC will continue increasing in the near future.

Generational differences in dietary pattern among Brazilian adults born between 1934 and 1975: a latent class analysis

OBJECTIVE

To identify generational differences in the dietary patterns of Brazilian adults born between 1934 and 1975.

DESIGN

A cross-sectional study from the baseline of the multicentre Brazilian Longitudinal Study of Adult Health (ELSA-Brasil) cohort. Year of birth was categorized into three birth generations: Traditionalists (born between 1934 and 1945); Baby Boomers (born between 1946 and 1964); and Generation X (born between 1965 and 1975). Food consumption was investigated using an FFQ. Latent class analysis (LCA) was used to identify data-driven dietary patterns.

SETTING

Brazil.

SUBJECTS

Individuals (n 15 069) aged 35-74 years.

RESULTS

A three-class model was generated from the LCA for each birth generation. Generation X presented higher energy intakes (kJ/kcal) from soft drinks (377·4/90·2) and sweets (1262·3/301·7) and lower energy intakes from fruit (1502·5/359·1) and vegetables (311·3/74·4) than Baby Boomers (283·7/67·8, 1047·7/250·4, 1756·0/419·7 and 365·3/87·3, respectively) and Traditionalists (186·2/44·5, 518·8/124·0, 1947·7/465·5 and 404·6/96·7, respectively). For Baby Boomers and Generation X, we found food patterns with similar structures: mixed pattern (22·7 and 29·7 %, respectively), prudent pattern (43·5 and 34·9 %, respectively) and processed pattern (33·8 and 35·4 %, respectively). Among Traditionalists, we could also identify mixed (30·9 %) and prudent (21·8 %) patterns, and a third pattern, named restricted dietary pattern (47·3 %).

CONCLUSIONS

The younger generation presented higher frequencies of consuming a pattern characterized by a low nutritional diet, compared with other generations, indicating that they may age with a greater burden of chronic diseases. It is important to develop public health interventions promoting healthy foods, focusing on the youngest generations.

Socioeconomic disparities in abdominal obesity over the life course in China

BACKGROUND

Abdominal obesity has become an important public health issue in China. Socioeconomic disparities are thought to be closely related to the prevalence of abdominal obesity. Exploring socioeconomic disparities in abdominal obesity over the life course in China could inform the design of new interventions to prevent and control abdominal obesity.

METHODS

The China Health and Nutrition Survey (CHNS) was a prospective household-based study involving seven rounds of surveys between 1993 and 2011. Twenty three thousand, two hundred and forty-three individuals were followed up over an 18-year period. The mixed effects models with random intercepts were used to assess the effects on abdominal obesity. Six key socioeconomic indicators, with age and age-squared added to the models, were used to identify socioeconomic disparities in abdominal obesity over the adult life course.

RESULTS

Prevalence of abdominal obesity increased non-linearly with age over the adult life course. Abdominal obesity was more prevalent in younger than older birth cohorts. Positive period effects on the prevalence of abdominal obesity were substantial from 1993 to 2011, and were stronger among males than females. Prevalence of abdominal obesity was higher among ethnic Han Chinese and among the married [coefficient (95% confidence intervals): 0.03(0.003, 0.057) and 0.035(0.022, 0.047), respectively], and was lower among males [coefficient (95% confidence intervals): - 0.065(- 0.075,-0.055)]. A higher-level of urbanization and higher household income increased the probability of abdominal obesity [coefficient (95% confidence intervals): 0.160(0.130, 0.191), 3.47E^- 4 (2.23E^- 4, 4.70E^- 4), respectively], while individuals with more education were less likely to experience abdominal obesity [coefficient (95% confidence intervals): - 0.222 (- 0.289, - 0.155)] across adulthood.

CONCLUSIONS

In China, abdominal obesity increased substantially in more recent cohorts. And people with lower educational attainment, with higher household income, or living in more urbanized communities may be the disadvantaged population of abdominal obesity over the adult life course. Effective interventions targeting the vulnerable population need to be developed.

Does stress influence sleep patterns, food intake, weight gain, abdominal obesity and weight loss interventions and vice versa?

Decades of research have reported only weak associations between the intakes of specific foods or drinks and weight gain and obesity. Randomized controlled dietary intervention trials have only shown very modest effects of changes in nutrient intake and diet composition on body weight in obese subjects. This review summarizes the scientific evidence on the role mental stress (either in or not in association with impaired sleep) may play in poor sleep, enhanced appetite, cravings and decreased motivation for physical activity. All these factors contribute to weight gain and obesity, possibly via decreasing the efficacy of weight loss interventions. We also review evidence for the role that lifestyle and stress management may play in achieving weight loss in stress-vulnerable individuals with overweight.

The Health of the Nation's Custodial Grandfathers and Older Single Fathers: Findings From the Behavior Risk Factor Surveillance System

Two important parent groups are solo grandfathers and single fathers raising children alone. The health of male caregivers raising children has received little attention by scholars. Investigating the health of single male caregivers raises awareness about their physical vulnerability. This study uses the 2012 Behavioral Risk Factor Surveillance System to compare health characteristics of 82 solo grandfathers with 396 single fathers aged 50 years and older. The findings suggest that grandfathers exhibited a high prevalence for various health conditions, including diabetes (44%), heart attack (27%), chronic obstructive pulmonary disease (23%), and stroke (6%). Almost half of grandfathers rated their health as fair/poor (47%), and nearly two in five had functional limitations (38%). Although older single fathers had better health characteristics than grandfathers, their health profile was poorer than population norms. Logistic regression analysis suggests that solo grandfathers are more at risk for poor health outcomes than older single fathers. Practice interventions to minimize health risks are discussed.

Population-Based Study of Changes in Arthritis Prevalence and Arthritis Risk Factors Over Time: Generational Differences and the Role of Obesity

OBJECTIVE

To investigate cohort effects in arthritis prevalence across 4 birth cohorts: World War II (born 1935-1944), older and younger baby boomers (born 1945-1954 and 1955-1964, respectively), and Generation X (born 1965-1974), and to determine whether birth cohort effects in arthritis prevalence were associated with differences in risk factors over time or period effects.

METHODS

Analysis of biannually collected data from the longitudinal Canadian National Population Health Survey, 1994-2011 (n = 8,817 at baseline). Data included self-reported arthritis diagnosed by a health professional, risk factors (years of education, household income, smoking, physical activity, sedentary behavior, body mass index [BMI]), and survey year as an indicator of period. We used hierarchical age-period-cohort analyses to compare the age trajectory of arthritis by birth cohort and to examine the contribution of changes in risk factors and period to cohort differences.

RESULTS

More recent cohorts had successively a greater prevalence of arthritis. Risk factors were significantly associated with arthritis prevalence independently of cohort differences. The effects of increasing education and income over time on potentially reducing the arthritis prevalence were almost counter-balanced by effects of increasing BMI. Significant cohort-BMI and age-BMI interactions indicated an earlier age of arthritis onset for obese individuals than those of normal weight.

CONCLUSION

Projections that only take into account the changing age structure of the population may underestimate future trends. Our understanding of the impact of BMI on arthritis is likely an underestimate. Cohort differences focus attention on the need to target arthritis management education to young and middle-aged adults.

Age-period-cohort analyses of obesity prevalence in US adults

OBJECTIVES

Age-period-cohort analysis is a stream of methodologies that decompose the temporal trends for disease risk into three time scales-age, calendar year (period) and year of birth (cohort). This study conducted age-period-cohort analyses of obesity prevalence in US adults.

STUDY DESIGN

Retrospective data analysis.

METHODS

We constructed regression models based on anthropometric data from the 1999-2012 National Health and Nutrition Examination Survey to correct for the self-reported height/weight in the 1984-2014 Behavioral Risk Factor Surveillance System (BRFSS). We estimated fixed-effects age-period-cohort models based on the BRFSS data for the overall adult sample (n = 6,093,293) and by sex and race/ethnicity, adjusting for individual characteristics and the BRFSS survey design.

RESULTS

An inverted U-shaped age effect on obesity and a positive period effect characterized by over-time increase in obesity risk independent of age and cohort influences were identified in the overall sample and subgroups by sex and race/ethnicity. From 1984 to 2014, the adjusted obesity prevalence increased by 21.1 percentage points among US adults, and 20.9, 21.6, 21.0, 26.4 and 20.1 percentage points in men, women, non-Hispanic whites, African Americans and Hispanics, respectively. In contrast, no consistent evidence was found in support of the cohort effect-the adjusted obesity risk was comparable across birth cohorts after accounting for the age and period effects.

CONCLUSIONS

Shifts in the age distribution and nationwide secular changes may have fuelled the obesity epidemic in the USA over the past decades. Reversing the obesity epidemic may require understanding of the nationwide changes over time that affect weight gain across all population subgroups and promoting universal changes to diet, physical activity and the obesogenic environment.

Non-linear pattern of age-specific bone mineral density and related factors in women: data from the 5th Korea National Health and Nutrition Examination Survey

Age-specific bone mineral density (BMD) of Korean women showed a nonlinear pattern. According to our study, this pattern could be mainly attributed to the nonlinear effects of body composition. Interventions targeting these factors in premenopausal women could be critical for achieving peak BMD.

PURPOSE

The patterns of age-specific bone mineral density (BMD) of femur and spine in women showed a non-unidirectional decrease, with ups and downs around the point of achieving peak BMD, that are not evident in men. We investigated the factors associated with these age-specific BMD in women using linear and nonlinear models.

METHODS

A total of 4681 women recruited during the 5th Korean National Health and Nutrition Examination Survey 2010-2011 (KNHANES V) were included. A range of related factors were considered including body compositional, reproductive, and socio-behavioral factors. Age-specific BMD was demonstrated using a generalized additive model (GAM) with smoothing spline transformation.

RESULTS

Age, lean body mass, fat mass, and age at menarche were significant predictors of BMD in premenopausal women. The GAM plot of BMD according to age revealed two peaks for total femur, femoral neck, and lumbar spine. After adjustment for body compositional factors, the peaks flattened. In the full model, the pattern for lumbar spine showed a single peak around the mid-40s. The GAM showed a generally better performance than the linear model for BMD at all three sites. Reduced models that included only lean body mass and fat mass best explained the variance of BMD in GAMs.

CONCLUSIONS

The BMD of Korean women in reproductive period could be largely attributed to the nonlinear effects of age and body compositional factors. Intervention targeting these factors could be critical for maintaining peak BMD.

Educational attainment and motor burden in Parkinson's disease

OBJECTIVE

Greater educational attainment is a protective factor for neurodegenerative dementias. If education earlier in life leads to greater cerebral reserve, it may play a similar protective role in Parkinson's disease (PD).

METHODS

We conducted a cross-sectional clinical imaging study of 142 subjects with PD. All subjects underwent [(11)C]dihydrotetrabenazine PET to confirm nigrostriatal dopaminergic denervation and brain MRI to estimate adjusted cortical gray matter volume (GMV).

RESULTS

After adjusting for possible confounders, including cognitive and dopaminergic covariates, as well as nonspecific neurodegeneration covariates (age, disease duration, and total adjusted cortical GMV), lower years of education remained a significant predictor of higher total MDS-UPDRS motor score (t = -3.28; P = 0.001). Education level associated inversely with white matter (WM) hyperintensities in a post-hoc analysis (n = 83).

CONCLUSIONS

Higher educational attainment is associated with lower severity of motor impairment in PD. This association may reflect an extranigral protective effect upon WM integrity.

The use of a chronic disease and risk factor surveillance system to determine the age, period and cohort effects on the prevalence of obesity and diabetes in South Australian adults--2003-2013

Background

Age, period and cohort (APC) analyses, using representative, population-based descriptive data, provide additional understanding behind increased prevalence rates.

Methods

Data on obesity and diabetes from the South Australian (SA) monthly chronic disease and risk factor surveillance system from July 2002 to December 2013 (n = 59,025) were used. Age was the self-reported age of the respondent at the time of the interview. Period was the year of the interview and cohort was age subtracted from the survey year. Cohort years were 1905 to 1995. All variables were treated as continuous. The age-sex standardised prevalence for obesity and diabetes was calculated using the Australia 2011 census. The APC models were constructed with ‘‘apcfit’’ in Stata.

Results

The age-sex standardised prevalence of obesity and diabetes increased in 2002-2013 from 18.6% to 24.1% and from 6.2% to 7.9%. The peak age for obesity was approximately 70 years with a steady increasing rate from 20 to 70 years of age. The peak age for diabetes was approximately 80 years. There were strong cohort effects and no period effects for both obesity and diabetes. The magnitude of the cohort effect is much more pronounced for obesity than for diabetes.

Conclusion

The APC analyses showed a higher than expected peak age for both obesity and diabetes, strong cohort effects with an acceleration of risk after 1960s for obesity and after 1940s for diabetes, and no period effects. By simultaneously considering the effects of age, period and cohort we have provided additional evidence for effective public health interventions.

Benefits gained, benefits lost: comparing baby boomers to other generations in a longitudinal cohort study of self-rated health

POLICY POINTS: Despite beliefs that baby boomers are healthier than previous generations, we found no evidence that the health of baby boomers is substantially different from that of the previous or succeeding cohorts. The effects of increased education, higher income, and lower smoking rates on improving self-rated health were nearly counterbalanced by the adverse effect of increasing body mass index (BMI). Assumptions that baby boomers will require less health care as they age because of better education, more prosperity, and less propensity to smoke may not be realized because of increases in obesity.

CONTEXT

Baby boomers are commonly believed to be healthier than the previous generation. Using self-rated health (SRH) as an indicator of health status, this study examines the effects of age, period, and birth cohort on the trajectory of health across 4 generations: World War II (born between 1935 and 1944), older baby boomers (born between 1945 and 1954), younger baby boomers (born between 1955 and 1964), and Generation X (born between 1965 and 1974).

METHODS

We analyzed Canada's longitudinal National Population Health Survey 1994-2010 (n = 8,570 at baseline), using multilevel growth models to estimate the age trajectory of SRH by cohort, accounting for period and incorporating the influence of changes in education, household income, smoking status, and body mass index (BMI) on SRH over time.

FINDINGS

SRH worsened with increasing age in all cohorts. Cohort differences in SRH were modest (p = 0.034), but there was a significant period effect (p = 0.002). We found marked cohort effects for increasing education, income, and BMI, and decreasing smoking from the youngest to the oldest cohorts, which were much reduced (education and smoking) or removed (income and BMI) once period was taken into account. At the population level, multivariable analysis showed the benefits of increasing education and income and declines in smoking on the trajectory of improving SRH were almost counterbalanced by the effects of increasing BMI (obesity).

CONCLUSIONS

We found no evidence to support the expectation that baby boomers will age more or less healthily than previous cohorts did. We also found that increasing BMI has likely undermined improvements in health that might have otherwise occurred, with possible implications for the need for health care. Period effects had a more profound effect than birth cohort effects. This suggests that interventions to improve health, such as reducing obesity, can be targeted to the entire, or a major portion of the, population and need not single out particular birth cohorts.

Should age-period-cohort studies return to the methodologies of the 1970s?

Social scientists have recognized the importance of age-period-cohort (APC) models for half a century, but have spent much of this time mired in debates about the feasibility of APC methods. Recently, a new class of APC methods based on modern statistical knowledge has emerged, offering potential solutions. In 2009, Reither, Hauser and Yang used one of these new methods - hierarchical APC (HAPC) modeling - to study how birth cohorts may have contributed to the U.S. obesity epidemic. They found that recent birth cohorts experience higher odds of obesity than their predecessors, but that ubiquitous period-based changes are primarily responsible for the rising prevalence of obesity. Although these findings have been replicated elsewhere, recent commentaries by Bell and Jones call them into question - along with the new class of APC methods. Specifically, Bell and Jones claim that new APC methods do not adequately address model identification and suggest that "solid theory" is often sufficient to remove one of the three temporal dimensions from empirical consideration. They also present a series of simulation models that purportedly show how the HAPC models estimated by Reither et al. (2009) could have produced misleading results. However, these simulation models rest on assumptions that there were no period effects, and associations between period and cohort variables and the outcome were perfectly linear. Those are conditions under which APC models should never be used. Under more tenable assumptions, our own simulations show that HAPC methods perform well, both in recovering the main findings presented by Reither et al. (2009) and the results reported by Bell and Jones. We also respond to critiques about model identification and theoretically-imposed constraints, finding little pragmatic support for such arguments. We conclude by encouraging social scientists to move beyond the debates of the 1970s and toward a deeper appreciation for modern APC methodologies.

Gender and reinforcing associations between socioeconomic disadvantage and body mass over the life course

Using the 1957-1993 data from the Wisconsin Longitudinal Study, we explore reciprocal associations between socioeconomic status (SES) and body mass in the 1939 birth cohort of non-Hispanic white men and women. We integrate the fundamental cause theory, the gender relations theory, and the life course perspective to analyze gender differences in (a) the ways that early socioeconomic disadvantage launches bidirectional associations of body mass and SES and (b) the extent to which these mutually reinforcing effects generate socioeconomic disparities in midlife body mass. Using structural equation modeling, we find that socioeconomic disadvantage at age 18 is related to higher body mass index and a greater risk of obesity at age 54, and that this relationship is significantly stronger for women than men. Moreover, women are more adversely affected by two mechanisms underlying the focal association: the obesogenic effect of socioeconomic disadvantage and the SES-impeding effect of obesity. These patterns were also replicated in propensity score-matching models. We conclude that gender and SES act synergistically over the life course to shape reciprocal chains of two disadvantaged statuses: heavier body mass and lower SES.

Obesity, abdominal obesity, physical activity, and caloric intake in US adults: 1988 to 2010

BACKGROUND

Obesity and abdominal obesity are associated independently with morbidity and mortality. Physical activity attenuates these risks. We examined trends in obesity, abdominal obesity, physical activity, and caloric intake in US adults from 1988 to 2010.

METHODS

Univariate and multivariate analyses were performed using National Health and Nutrition Examination Survey data.

RESULTS

Average body mass index (BMI) increased by 0.37% (95% confidence interval [CI], 0.30-0.44) per year in both women and men. Average waist circumference increased by 0.37% (95% CI, 0.30-0.43) and 0.27% (95% CI, 0.22-0.32) per year in women and men, respectively. The prevalence of obesity and abdominal obesity increased substantially, as did the prevalence of abdominal obesity among overweight adults. Younger women experienced the greatest increases. The proportion of adults who reported no leisure-time physical activity increased from 19.1% (95% CI, 17.3-21.0) to 51.7% (95% CI, 48.9-54.5) in women, and from 11.4% (95% CI, 10.0-12.8) to 43.5% (95% CI, 40.7-46.3) in men. Average daily caloric intake did not change significantly. BMI and waist circumference trends were associated with physical activity level but not caloric intake. The associated changes in adjusted BMIs were 8.3% (95% CI, 6.9-9.6) higher among women and 1.7% (95% CI, 0.68-2.8) higher among men with no leisure-time physical activity compared with those with an ideal level of leisure-time physical activity.

CONCLUSIONS

Our analyses highlight important dimensions of the public health problem of obesity, including trends in younger women and in abdominal obesity, and lend support to the emphasis placed on physical activity by the Institute of Medicine.

Are Baby Boomers healthier than Generation X? A profile of Australia's working generations using National Health Survey data

Background

To determine differences in sociodemographic and health related characteristics of Australian Baby Boomers and Generation X at the same relative age.

Methods

The 1989/90 National Health Survey (NHS) for Boomers (1946–1965) and the 2007/08 NHS for Generation Xers (1966–1980) was used to compare the cohorts at the same age of 25–44 years. Generational differences for males and females in education, employment, smoking, physical activity, Body Mass Index (BMI), self-rated health, and diabetes were determined using Z tests. Prevalence estimates and p-values are reported. Logistic regression models examining overweight/obesity (BMI≥25) and diabetes prevalence as the dependent variables, with generation as the independent variable were adjusted for sex, age, education, physical activity, smoking and BMI(diabetes model only). Adjusted odds ratios (OR) and 95% confidence intervals are reported.

Results

At the same age, tertiary educational attainment was higher among Generation X males (27.6% vs. 15.2% p<0.001) and females (30.0% vs. 10.6% p<0.001). Boomer females had a higher rate of unemployment (5.6% vs. 2.5% p<0.001). Boomer males and females had a higher prevalence of “excellent” self-reported health (35.9% vs. 21.8% p<0.001; 36.3% vs. 25.1% p<0.001) and smoking (36.3% vs. 30.4% p<0.001; 28.3% vs. 22.3% p<0.001). Generation X males (18.3% vs. 9.4% p<0.001) and females (12.7% vs. 10.4% p = 0.015) demonstrated a higher prevalence of obesity (BMI>30). There were no differences in physical activity. Modelling indicated that Generation X were more likely than Boomers to be overweight/obese (OR:2.09, 1.77–2.46) and have diabetes (OR:1.79, 1.47–2.18).

Conclusion

Self-rated health has deteriorated while obesity and diabetes prevalence has increased. This may impact workforce participation and health care utilization in the future.

Changing incidence of orthopedic surgery in rheumatic disease: contributing factors

Rheumatic diseases are multisystem conditions that predominantly affect the musculoskeletal system, leading to soft tissue and articular damage. Historically, medical therapy was able to slow, but not prevent, erosion and joint destruction, resulting in the frequent need for orthopedic procedures to maintain function and minimize pain. However, the widespread use of disease-modifying anti-rheumatic drugs (DMARDs) and biologic therapy over the last twenty years has resulted in a dramatic decrease in the incidence of musculoskeletal damage and impairment among these patients. This review will discuss changing patterns of orthopedic surgery among patients with rheumatic diseases, focusing on rheumatoid arthritis and systemic lupus erythematosus.

Disruption of the gastroesophageal junction by central obesity and waist belt: role of raised intra-abdominal pressure

Obesity is a major reason for the recent increase in incidence of reflux disease and cancers at the distal esophagus and gastroesophageal junction (GOJ) and is mediated through a rise in the intra-abdominal pressure (IAP) but the exact mechanisms are unclear. Raised IAP from obesity and with application of waist belt produces mechanical distortion of the GOJ through formation of partial hiatus hernia. Even though there is no trans-sphincteric acid reflux, there is increased ingress of acid into the lower sphincter (intra-sphincteric reflux) as a consequence of raised IAP. In addition, short segment acid reflux is more evident in obese subjects with a belt on. Acid pocket is also enlarged in hiatus hernia, and acts as a reservoir of acid available to reflux whenever the sphincter fails. Above mechanisms may explain the common occurrence of cardiac lengthening and inflammation found in asymptomatic obese subjects. The inflamed cardia is also immunohistochemically similar to non-intestinal Barrett's mucosa, which is of etiological importance for cancers at the GOJ. Interventions that can reduce the mechanical distortion and acid exposure at the GOJ, including diet, exercise, drugs, sphincter augmentation therapy, and surgery, are clinically relevant in the treatment of gastroesophageal reflux disease but more data are needed whether if these strategies are also effective in preventing cancer. As a conclusion, raised IAP produces silent mechanical disruption of the GOJ, which may explain the high occurrence of cancers in this region and it is potentially reversible with early interventions.

Pre-eclampsia rates in the United States, 1980-2010: age-period-cohort analysis

OBJECTIVE

To estimate the contributions of biological aging, historical trends, and birth cohort effects on trends in pre-eclampsia in the United States.

DESIGN

Population based retrospective study.

SETTING

National hospital discharge survey datasets, 1980-2010, United States.

PARTICIPANTS

120 million women admitted to hospital for delivery.

MAIN OUTCOME MEASURES

Temporal changes in rates of mild and severe pre-eclampsia in relation to maternal age, year of delivery, and birth cohorts. Poisson regression as well as multilevel age-period-cohort models with adjustment for obesity and smoking were incorporated.

RESULTS

The rate of pre-eclampsia was 3.4%. The age-period-cohort analysis showed a strong age effect, with women at the extremes of maternal age having the greatest risk of pre-eclampsia. In comparison with women delivering in 1980, those delivering in 2003 were at 6.7-fold (95% confidence interval 5.6-fold to 8.0-fold) increased risk of severe pre-eclampsia. Period effects declined after 2003. Trends for severe pre-eclampsia also showed a modest birth cohort effect, with women born in the 1970s at increased risk. Compared with women born in 1955, the risk ratio for women born in 1970 was 1.2 (95% confidence interval 1.1 to 1.3). Similar patterns were also evident for mild pre-eclampsia, although attenuated. Changes in the population prevalence of obesity and smoking were associated with period and cohort trends in pre-eclampsia but did not explain the trends.

CONCLUSIONS

Rates of severe pre-eclampsia have been increasing in the United States and age-period-cohort effects all contribute to these trends. Although smoking and obesity have driven these trends, changes in the diagnostic criteria may have also contributed to the age-period-cohort effects. Health consequences of rising obesity rates in the United States underscore that efforts to reduce obesity may be beneficial to maternal and perinatal health.