Pre-pregnancy body mass index and time to pregnancy among couples pregnant within a year: A China cohort study

Background. Higher body mass index (BMI) is associated with subfertility in women and men. This relationship is further substantiated by a few small randomized-controlled trials of weight reduction and success of assisted reproduction. The aim of the current study was to expand the current evidence-base by investigating the association between BMI and subfertility in men and women using multivariable regression and Mendelian randomization. Methods and findings. We studied 34,157 women (average age 30, average BMI 23.1 kg/m2) and 31,496 men (average age 33, average BMI 25.4 kg/m2) who were genotyped and are participating in the Norwegian Mother, Father and Child Cohort Study. Self-reported information was available on time-to-pregnancy and BMI. A total of 10% of couples were subfertile (time-to-pregnancy ≥12 months). Our findings support a J-shaped association between BMI and subfertility in both sexes using multivariable logistic regression models. Non-linear Mendelian randomization validated this relationship. A 1 kg/m2 greater genetically predicted BMI was linked to 15% greater odds of subfertility (95% confidence interval 4% to 28%) in obese women (>=30.0 kg/m2) and 14% lower odds of subfertility (-25% to -3%) in women with BMI <20.0 kg/m2. A 1 kg/m2 higher genetically predicted BMI was linked to 23% greater odds of subfertility (6% to 43%) among obese men and 36% decreased odds (-62% to 7%) among men BMI <20.0 kg/m2. A genetically predicted BMI of 23 and 25 kg/m2 was linked to the lowest subfertility risk in women and men, respectively. The main limitations of our study were that we did not know whether the subfertility was driven by the woman, man, or both; the exclusive consideration of individuals of northern European ancestry; and the limited amount of participants with obesity or BMI values <20.0 kg/m2. Conclusions. We observed a J-shaped relationship between BMI and subfertility in both sexes, when using both a standard multivariable regression and Mendelian randomization analysis, further supporting a potential causal role of BMI on subfertility.

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Faculty Opinions recommendation of A longitudinal cohort study of body mass index and childhood exposure to secondhand tobacco smoke and air pollution: the Southern California Children's Health Study.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.725233321.793523296 ◽

2016 ◽

Author(s):

Sundeep Salvi

Keyword(s):

Body Mass Index ◽

Air Pollution ◽

Cohort Study ◽

Body Mass ◽

Tobacco Smoke ◽

Longitudinal Cohort Study ◽

Health Study ◽

Childhood Exposure ◽

Longitudinal Cohort ◽

Secondhand Tobacco Smoke

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Longitudinal Body Mass Index Trajectories and Incident Chronic Kidney Disease in the General Population: Community-Based Cohort Study

SSRN Electronic Journal ◽

10.2139/ssrn.3541109 ◽

2020 ◽

Author(s):

Hae-Ryong Yun ◽

Hyung Woo Kim ◽

Tae Ik Chang ◽

Ea Wha Kang ◽

HyeonSeon Lim ◽

...

Keyword(s):

Body Mass Index ◽

Chronic Kidney Disease ◽

Cohort Study ◽

Kidney Disease ◽

General Population ◽

Body Mass ◽

Community Based ◽

Incident Chronic Kidney Disease ◽

Body Mass Index Trajectories

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Long-term body mass index changes in overweight and obese adults and the risk of heart failure, cardiovascular disease and mortality: a cohort study of over 260,000 adults in the UK

BMC Public Health ◽

10.1186/s12889-021-10606-1 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Barbara Iyen ◽

Stephen Weng ◽

Yana Vinogradova ◽

Ralph K. Akyea ◽

Nadeem Qureshi ◽

...

Keyword(s):

Heart Failure ◽

Cardiovascular Disease ◽

Body Mass Index ◽

Cohort Study ◽

Body Mass ◽

World Health ◽

Obese Adults ◽

Bmi Trajectories ◽

The Impact

Abstract Background Although obesity is a well-recognised risk factor for cardiovascular disease (CVD), the impact of long-term body mass index (BMI) changes in overweight or obese adults, on the risk of heart failure, CVD and mortality has not been quantified. Methods This population-based cohort study used routine UK primary care electronic health data linked to secondary care and death-registry records. We identified adults who were overweight or obese, free from CVD and who had repeated BMI measures. Using group-based trajectory modelling, we examined the BMI trajectories of these individuals and then determined incidence rates of CVD, heart failure and mortality associated with the different trajectories. Cox-proportional hazards regression determined hazards ratios for incident outcomes. Results 264,230 individuals (mean age 49.5 years (SD 12.7) and mean BMI 33.8 kg/m2 (SD 6.1)) were followed-up for a median duration of 10.9 years. Four BMI trajectories were identified, corresponding at baseline, with World Health Organisation BMI classifications for overweight, class-1, class-2 and class-3 obesity respectively. In all four groups, there was a small, stable upwards trajectory in BMI (mean BMI increase of 1.06 kg/m2 (± 3.8)). Compared with overweight individuals, class-3 obese individuals had hazards ratios (HR) of 3.26 (95% CI 2.98–3.57) for heart failure, HR of 2.72 (2.58–2.87) for all-cause mortality and HR of 3.31 (2.84–3.86) for CVD-related mortality, after adjusting for baseline demographic and cardiovascular risk factors. Conclusion The majority of adults who are overweight or obese retain their degree of overweight or obesity over the long term. Individuals with stable severe obesity experience the worst heart failure, CVD and mortality outcomes. These findings highlight the high cardiovascular toll exacted by continuing failure to tackle obesity.

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