Lower fertility associated with obesity and underweight: the US National Longitudinal Survey of Youth

Prevalence and risk factors of obesity among undergraduate student population in Ghana: an evaluation study of body composition indices

BACKGROUND

Obesity is a classified risk factor for several of the world's leading causes of death. In this study, we combined information contained in body mass index (BMI), total percentage body fat (TPBF) and relative fat mass (RFM) to estimate obesity prevalence and examine the risk factors associated with obesity.

METHODS

The study recruited 1027 undergraduate students aged between 16 and 25 years using a cross-sectional study design and two-stage stratified random sampling between January and April 2019 from the Kwame Nkrumah University of Science and Technology, Kumasi, Ghana. Demographic, lifestyle, and family history of chronic disease data, were collected using a structured questionnaire. Bioelectrical impedance, along with height, weight, age, and gender, were used to estimate BMI and TPBF. The RFM was calculated using a published equation. The TPBF and RFM ranges were evaluated based on standard BMI thresholds and an informative combined obesity prevalence estimated in a Bayesian framework. Multiple logistic regression analysis was used to evaluate potential risk factors of overweight/obesity.

RESULTS

Concordance between BMI, TPBF and RFM for obesity classification was 84% among female and 82.9% among male students. The Bayesian analysis revealed a combined prevalence means of obesity of 9.4% (95%CI: 6.9-12.2%) among female students and 6.7% (95%CI:4.3-9.5%) among male students. The odds of obesity were increased between 1.8 and 2.5 for females depending on the classification index. A significant increasing trend of obesity was observed with university-level. A family history of obesity was associated with a high estimate of general, central, and high TPBF.

CONCLUSION

Using multiple adiposity indicators conjointly in a Bayesian framework offers a greater power to examine obesity prevalence. We have applied this and reported high obesity prevalence, especially among female students. University level and family history of obesity were key determinants for obesity among the student population.

Male obesity: Associated effects on fertility and the outcomes of offspring

Obesity rates are increasing globally, making it imperative to comprehend the effects of parental obesity on human reproduction. This review aims to highlight the impact of male obesity on reproductive and offspring outcomes. Male obesity has been shown to affect fertility through various mechanisms, including changes in semen quality, difficulty with natural conception, and worsened assisted reproductive technology outcomes. The evidence regarding the impact of male obesity on success of sperm retrieval is conflicting, but all aforementioned adverse effects may be modifiable with weight loss. Moreover, paternal obesity may influence atypical offspring outcomes, such as placental abnormalities and disruptions in fetal development, which may be moderated by epigenetic pathways. Further research is needed to fully understand the complex relationships and underlying mechanisms involved. Gaining more insight into the impact of male obesity on fertility and offspring outcomes can aid in the development of targeted interventions to improve family planning and the health of future generations.

Association between childhood obesity and infertility in later life: a systematic review of cohort studies

BACKGROUND

The global prevalence of childhood obesity has exhibited a troubling surge in recent years. Due to the raised questions regarding its potential correlation with infertility in adulthood, this systematic review has been undertaken to explore the relationships between childhood obesity, and infertility later in life.

METHODS

A comprehensive search was performed in three international databases (PubMed, Web of Science, and Scopus). All cohort (retrospective or prospective), case-cohort, and nested case-control studies until April 2022 which assessed the association of obesity in children and adolescents with male and female infertility indicators in later life were included. The quality of the included studies was assessed by Newcastle-Ottawa quality assessment checklists.

RESULT

Out of the initial 32,501 documents, eleven eligible studies with a total sample size of 498,980 participants were included. Five studies focused on the number of offspring and indicated that obesity, especially in adolescence had an association with later life lower number of children, nulliparity, and childlessness in both men and women. Concerning conceiving problems, two studies showed that obesity before age 12 increased the risk of female fertility problems in the future. Two studies reported that obesity in early life raised the risk of impaired female reproductive system such as menstrual or ovulatory problems. As well as females, a study discovered that obesity in men during their 20s was linked to an elevated risk of low sperm motility and poor sperm morphology. Another study has reported men with higher pre-pubertal BMI had lower sex hormone-binding globulin; however, the same association was not seen between childhood BMI and semen quality.

CONCLUSION

The evidence suggests a positive association between childhood obesity with infertility indicators in later life. Childhood weight reduction strategies are suggested to be implemented in societies in order to reduce infertility rates in later life.

COVID-19: quarantine, isolation, and lifestyle diseases

Within just a month of the first case of idiopathic pneumonia, on 30 January 2020, WHO declared the outbreak, a Public Health Emergency of International Concern. On 11 February 2019, the Internal Committee on Taxonomy of Virus (ICTV) announced the name of the novel virus as "severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)" and on 11 March 2020, WHO declared it a global pandemic. As a preventive measure, the government of several countries has imposed quarantine and isolation for preventing the further spread of disease. Both of these restrict outdoor activities, which can directly affect the lifestyle of citizens. Quarantine for the long term can result in increased lifestyle disease, mainly cardiovascular diseases, and obesity.

Association of undernutrition and female infertility in East Africa: Finding from multi-country demographic and health surveys

Introduction

Infertility is one of the public health problems affecting a significant number of women in the reproductive age group. Although female fertility is predominantly affected by gynecological and systemic diseases, lifestyle and nutritional factors also play an important role in secondary female infertility. Therefore, this study aimed to determine the pooled prevalence of secondary female infertility and its association with undernutrition using nationwide data from the Demographic and Health Surveys (DHS) of eastern African countries.

Methods

The data of ten East African countries that comprise a weighted sample of 38,020 women data were accessed from measure DHS. Data processing and analysis were performed using STATA 15 software. A multilevel mixed-effect logistic regression model was fitted to examine the association between undernutrition and secondary infertility. Variables with a p-value < 0.05 were declared as significant factors associated with secondary infertility. Model comparison was done based on Akaike and Bayesian Information Criteria (AIC and BIC). To measure variation (random effects), Community-level variance with standard deviation and intra-cluster correlation coefficient (ICC) was used.

Result

The proportion of women who have secondary infertility was 16.32% with 95%CI (15.96, 16.69), of which 26.94% were undernourished. This study found that being undernutrition (AOR = 1.74; 95%CI: 1.54-1.98) and overweight (AOR = 1.72; 95%CI: 1.62-1.86) were significantly associated with secondary infertility. Women aged >35 years (AOR = 3.47; 95%CI: 2.66-4.55), and rural residents (AOR = 1.16; 95%CI: 1.02-1.37) are other factors that are positively associated with secondary infertility. However, primary education (AOR = 0.87; 95%CI: 0.77-0.97) and richer wealth index (AOR = 0.84; 95%CI: 0.73-0.97) are protective factors for secondary infertility.

Conclusion

This study indicated that there is a strong association between secondary infertility and undernutrition growing in Eastern Africa. Therefore, Health information dissemination and awareness creation on the impact of malnutrition on infertility should be given to the community and health care providers. Given this, it may lead to integrating nutrition counseling into both clinical settings for infertility management as well as national dietary guidelines for individuals of reproductive age.

An optimal growth pattern during pregnancy and early childhood associates with better fertility in men

OBJECTIVE

This study aimed to evaluate the association between birth weight (BW), childhood and adolescent BMI, with reproductive capacity in men.

DESIGN

A prospective, population-based cohort study (Northern Finland birth cohort 1966).

METHODS

Around 6196 men born in 1966 were followed from birth to age 50 years. Weight and height were measured repeatedly by professionals. Reproductive capacity (infertility assessment, male factor infertility and infertility treatment by age 46 years) was evaluated by questionnaires at ages 31 and 46 years. The number of children by the age of 50 years was recovered from registers. After excluding the men who reported never having attempted to have children or not answering the question at age 31 or 46 years (n = 2041), 4128 men were included in the final study population. Results were adjusted for BW, BW for gestational age (GA), mother's smoking status, marital status, educational level and smoking status.

RESULTS

Being small for GA (10.5% vs 8.2%, P = 0.012) or having a lower BW (3495 g vs 3548 g, P = 0.003) were associated with childlessness. The association was however no longer significant after adjusting for marital status. Being underweight in early childhood was associated with an increased risk of infertility assessment (adjusted, aOR: 2.04(1.07-3.81)) and childlessness (aOR: 1.47(1.01-2.17)) compared to the normal weight group. Conversely, overweight or obesity in early childhood was associated with a decreased risk of infertility assessment (aOR: 0.60 (0.41-0.87)), treatment (aOR: 0.42 (0.25-0.70)) and male factor infertility (aOR: 0.45 (0.21-0.97)). BMI in mid-childhood or puberty had no association with infertility or childlessness.

CONCLUSION

In boys, an optimal growth trajectory during pregnancy and early childhood seems to be very important for life-long fertility.

Sexually antagonistic selection on educational attainment and body size in Estonian children

Natural selection is a key mechanism of evolution, which results from the differential reproduction of phenotypes. We describe fecundity selection at different parity transitions on 15 anthropometric traits and educational attainment in Estonian children sampled in the middle of 20th century. The direction of selection on educational attainment and bodily traits was sexually antagonistic, and it occurred via different parity transitions in boys and girls. Compared to boys with primary education, obtaining tertiary education was associated with 3.5 times and secondary education two times higher odds of becoming a father. Transition to motherhood was not related to educational attainment, while education above primary was associated with lower odds (OR = 0.5-0.7) to progression to parities above one and two. Selection on anthropometric traits occurred almost exclusively via childlessness in boys, while among the girls, most of the traits that were associated with becoming a mother were additionally associated with a transition from one child to higher parities. Male (but not female) fitness was thus primarily determined by traits related to mating success. Selection favored stronger and larger boys and smaller girls. Selection on girls favored some traits that associate with perceived femininity, while other feminine traits were selected against.

Prevalence of thinness and its effect on height velocity in schoolchildren

Objective

In contrast to childhood obesity, studies involving thin children are much fewer, especially in developed countries. Furthermore, most reports do not address the impact of childhood thinness on height velocity. This study investigated the prevalence of thinness and its effect on height velocity in schoolchildren in the United Arab Emirates (UAE). Weight and height were measured in 29,410 schoolchildren (50.5% females), as part of the health assessment (academic year 2014–2015). The body mass index (BMI) was classified as normal, thinness, overweight, or obese using cutoffs established by the International Obesity Task Force (IOTF), World Health Organization, and Centers for Disease Control.

Results

The median age was 10.2 years (range, 3–19). Using the IOTF scale, one-quarter of the children aged 4–6 years and one-third of the children aged 7–9 years were thin (BMI ≤ 18.5 kg/m²). Thinness was less prevalent (8–10%) in adolescents. Group peak height velocity was delayed 1–3 years in thin children and was higher in children with excess body fat. In conclusion thinness was the highest (25–33%) in children aged 4–9 years of age and their peak height velocity was delayed 1–3 years when compared to the other children.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13104-021-05500-3.

Mendelian randomisation approaches to the study of prenatal exposures: A systematic review

BACKGROUND

Mendelian randomisation (MR) designs apply instrumental variable techniques using genetic variants to study causal effects. MR is increasingly used to evaluate the role of maternal exposures during pregnancy on offspring health.

OBJECTIVES

We review the application of MR to prenatal exposures and describe reporting of methodologic challenges in this area.

DATA SOURCES

We searched PubMed, EMBASE, Medline Ovid, Cochrane Central, Web of Science, and Google Scholar.

STUDY SELECTION AND DATA EXTRACTION

Eligible studies met the following criteria: (a) a maternal pregnancy exposure; (b) an outcome assessed in offspring of the pregnancy; and (c) a genetic variant or score proposed as an instrument or proxy for an exposure.

SYNTHESIS

We quantified the frequency of reporting of MR conditions stated, techniques used to examine assumption plausibility, and reported limitations.

RESULTS

Forty-three eligible studies were identified. When discussing challenges or limitations, the most common issues described were known potential biases in the broader MR literature, including population stratification (n = 29), weak instrument bias (n = 18), and certain types of pleiotropy (n = 30). Of 22 studies presenting point estimates for the effect of exposure, four defined their causal estimand. Twenty-four studies discussed issues unique to prenatal MR, including selection on pregnancy (n = 1) and pleiotropy via postnatal exposure (n = 10) or offspring genotype (n = 20).

CONCLUSIONS

Prenatal MR studies frequently discuss issues that affect all MR studies, but rarely discuss problems specific to the prenatal context, including selection on pregnancy and effects of postnatal exposure. Future prenatal MR studies should report and attempt to falsify their assumptions, with particular attention to issues specific to prenatal MR. Further research is needed to evaluate the impacts of biases unique to prenatal MR in practice.

Association between age at menarche and body mass index, waist circumference, waist to hip ratio, and waist to height ratio in adult women

OBJECTIVES

The aim of the present study was to examine associations between age at menarche and body mass index (BMI), waist circumference (WC), waist-to-height ratio (WHtR), and waist-to-hip ratio (WHR) in young adult women.

METHODS

Anthropometric data and age at menarche information were collected in two cross-sectional surveys conducted in the years 2004-2006 (Cohort 1) and 2016-2018 (Cohort 2). A total of 2419 women, aged 19-24 years., were included.

RESULTS

Statistically significant relationships between age at menarche and BMI, WHtR, and WC were observed. The values of the anthropometric parameters decreased with increasing age at menarche. The onset of menstruation before the age of 12 years. was linked to a heightened risk of overweight and obesity (BMI ≥ 25) and abdominal obesity defined as WC > 80 cm and/or WHtR ≥ 0.5. First menstruation after the age of 14 y. was associated with a lower risk of overweight and obesity (BMI ≥ 25, WC > 80 cm and/or WHtR ≥ 0.5), as well as a higher risk of being underweight (BMI < 18.5 and/or WHtR < 0.4). Associations between anthropometry and menarcheal timing were stronger in Cohort 1.

CONCLUSION

Both early and late onset of menarche are associated with abnormal body composition: Early menarche is associated with overweight, while later maturing girls have a heightened risk of underweight.

Overweight/obesity among 15- to 24-year-old women in Ghana: 21-year trend, future projections and socio-demographic correlates

Although developing countries are experiencing some of the fastest rises in the prevalence of adult overweight and obesity, little is known about the pace of the problem among young people in transition from adolescence to adulthood. This study examined the trend and associated socio-demographic predictors of overweight/obesity (BMI ≥25kg/m2) from 1993 to 2014 among women aged 15-24 years in Ghana and projected the future prevalence from 2019 to 2040. Descriptive statistics, the arithmetic linear change model, and binary logistic regression were applied to data on women aged 15-24 years from five nationally representative Ghana Demographic and Health Surveys conducted in 1993 (N=488), 1998 (N=517), 2003 (N=1832), 2008 (N=1693) and 2014 (N=1491). Overall, overweight/obesity among women aged 15-24 years almost tripled between the 1993 (6.8%; 95% CI=4.9-9.3) and 2014 (19.5%; 95% CI=17.3-21.2) surveys. Based on the arithmetic linear change model, overweight/obesity is projected to increase linearly to over 35% among the 15-24 year cohort of women by 2040. Age, educational level, wealth status, occupation, type of locality, ethnicity, frequency of viewing TV per week, parity and contraceptive use were found to be significant predictors of overweight/obesity among this sub-group of women. The trend of overweight/obesity demonstrated in this group of women could potentially provide momentum for further increases in the prevalence of overweight/obesity and associated health outcomes in the coming years in Ghana. This underscores the need for urgent national-level public health intervention efforts to curtail the problem.

Nutrition and Female Fertility: An Interdependent Correlation

Besides aging, a number of non-modifiable lifestyle-related factors, such as smoking, elevated consumption of caffeine and alcohol, stress, agonist sports, chronic exposure to environmental pollutants, and other nutritional habits exert a negative impact on a women's fertility. In particular, metabolic disorders including diabetes, obesity, and hyperlipidemia commonly associated to hypercaloric diets are suspected to affect a woman's fertility either by direct damage to oocyte health and differentiation, or by indirect interference with the pituitary-hypothalamic axis, resulting in dysfunctional oogenesis. Obese women show decreased insulin sensitivity determining persistent hyperinsulinemia, which may be involved in the pathogenesis of Polycystic Ovary Syndrome. Thus, the reduced insulin secretion induced by dietary adjustments is an attractive non-pharmacological treatment to prevent infertility, and a Mediterranean diet aimed at maintaining normal body mass may be effective in the preservation of ovarian health and physiology. Furthermore, in relation to the oxidative stress as a co-factor of defective oocyte maturation, an appropriate intake of proteins, antioxidants and methyl-donor supplements (1-Carbon Cycle) may decrease the bioavailability of toxic oxidants resulting in the protection of oocyte maturation.

Reproductive Outcomes Among Women with Eating Disorders or Disordered Eating Behavior: Does Methodological Approach Shape Research Findings?

BACKGROUND

There is a well-documented link between eating disorders (EDs) and adverse health outcomes, including fertility difficulties. These findings stem largely from clinical data or samples using a clinical measure (e.g., diagnosis) of EDs, which may limit our understanding of how EDs or disordered eating behaviors (DEBs) shape female fertility.

METHODS

We compared reproductive outcomes from two longitudinal data sources, clinical and population-based data from the Utah Population Database (UPDB) (N = 6,046), and nonclinical community-based data from the National Longitudinal Study of Adolescent to Young Adult Health (Add Health) (N = 5,951). We examined age at first birth using Cox regression and parity using negative binomial regression.

RESULTS

Using the UPDB data, women with diagnosed ED experienced later ages of first birth (hazard rate ratio [HRR] = 0.38; p < 0.01) and lower parity (incidence rate ratio [IRR] = 0.38; p < 0.01) relative to women without EDs. Using the Add Health sample, women who self-reported DEB experienced earlier age of first birth (HRR = 1.16; p < 0.05) and higher parity (IRR = 1.17; p < 0.01) relative to women without DEB.

CONCLUSIONS

Conflicting results suggest two sets of mechanisms, physical/biological (sex specific) and social/behavioral (gender specific), may be simultaneously shaping the reproductive outcomes of women with histories of EDs or DEB. Discipline-specific methodology likely shapes Women's Health research outcomes.

Do the Low WHRs and BMIs Judged Most Attractive Indicate Higher Fertility?

We examine the widely accepted view that very low waist-hip ratios and low body mass indices (BMIs) in women in well-nourished populations are judged attractive by men because these features reliably indicate superior fertility. In both subsistence and well-nourished populations, relevant studies of fertility do not support this view. Rather studies indicate lower fertility in women with anthropometric values associated with high attractiveness. Moreover, low maternal BMI predisposes to conditions that compromise infant survival. Consistent with these findings from the literature, new data from a large U.S. sample of women past reproductive age show that women with lower BMIs in the late teens had fewer live births, controlling for education, marital history, and race. They also had later menarche and earlier menopause compared with women with higher youth BMIs. In addition, data from the 2013 U.S. natality database show that mothers with lower prepregnancy BMIs have an increased risk of producing both low-birth-weight and preterm infants controlling for other relevant variables-conditions that would have adversely affected fitness over almost all of human evolution. Thus, a review of the relevant literature and three new tests fail to support the view that highly attractive women are more fertile.

Childhood adiposity and fertility difficulties: the Bogalusa Heart Study

BACKGROUND

Adult obesity is associated with infertility; however, childhood obesity has received little consideration.

OBJECTIVES

The present study sought to evaluate the impact of childhood adiposity on fertility.

METHODS

Associations between childhood adiposity and self-reported fertility difficulties were estimated among women participating in a long-term study of cardiovascular risks and reproductive health (n = 1061).

RESULTS

Participants with obesity between ages 9 and 12 were more likely to report fertility difficulties (adjusted relative risk [aRR], 1.82, 95% CI 1.17-2.82) and inability to become pregnant when trying (aRR = 1.94, 95% CI 1.22-3.08) as were those with obesity prior to age 9 (aRR = 1.76, 95% CI 1.04-2.97). Similar associations were seen among those ever overweight or obese in childhood. High subscapular skinfold thickness (age < 12) increased risk of receiving help becoming pregnant (aRR = 2.16, 95% CI 1.15-4.06), inability to become pregnant (aRR = 1.46, 95% CI 1.05-2.04) and any fertility difficulties (aRR = 1.56, 95% CI 1.13-2.14); associations for triceps skinfold were attenuated. Participants with increased adiposity also had fewer pregnancies and live births. Effects persisted, excluding women with polycystic ovarian syndrome.

CONCLUSIONS

This study supports an association between childhood adiposity and infertility, not solely driven by polycystic ovarian syndrome.

Sexual dimorphisms in genetic loci linked to body fat distribution

Obesity is a chronic condition associated with increased morbidity and mortality and is a risk factor for a number of other diseases including type 2 diabetes and cardiovascular disease. Obesity confers an enormous, costly burden on both individuals and public health more broadly. Body fat distribution is a heritable trait and a well-established predictor of adverse metabolic outcomes. Body fat distribution is distinct from overall obesity in measurement, but studies of body fat distribution can yield insights into the risk factors for and causes of overall obesity. Sexual dimorphism in body fat distribution is present throughout life. Though sexual dimorphism is subtle in early stages of life, it is attenuated in puberty and during menopause. This phenomenon could be, at least in part, due to the influence of sex hormones on the trait. Findings from recent large genome-wide association studies (GWAS) for various measures of body fat distribution (including waist-to-hip ratio, hip or waist circumference, trunk fat percentage and the ratio of android and gynoid fat percentage) emphasize the strong sexual dimorphism in the genetic regulation of fat distribution traits. Importantly, sexual dimorphism is not observed for overall obesity (as assessed by body mass index or total fat percentage). Notably, the genetic loci associated with body fat distribution, which show sexual dimorphism, are located near genes that are expressed in adipose tissues and/or adipose cells. Considering the epidemiological and genetic evidence, sexual dimorphism is a prominent feature of body fat distribution. Research that specifically focuses on sexual dimorphism in fat distribution can provide novel insights into human physiology and into the development of obesity and its comorbidities, as well as yield biological clues that will aid in the improvement of disease prevention and treatment.

Developmental influences on fertility decisions by women: an evolutionary perspective

Developmental environments are crucial for shaping our life course. Elements of the early social and biological environments have been consistently associated with reproduction in humans. To date, a strong focus has been on the relationship between early stress, earlier menarche and first child birth in women. These associations, found predominately in high-income countries, have been usefully interpreted within life-history theory frameworks. Fertility, on the other hand--a missing link between an individual's early environment, reproductive strategy and fitness--has received little attention. Here, we synthesize this literature by examining the associations between early adversity, age at menarche and fertility and fecundity in women. We examine the evidence that potential mechanisms such as birth weight, childhood body composition, risky health behaviours and developmental influences on attractiveness link the early environment and fecundity and fertility. The evidence that menarche is associated with fertility and fecundity is good. Currently, owing to the small number of correlational studies and mixed methodologies, the evidence that early adversity predicts fecundity and fertility is not conclusive. This area of research is in its infancy; studies examining early adversity and adult fertility decisions that can also examine likely biological, social and psychological pathways present opportunities for future fertility research.

Socio-demographic trends in overweight and obesity among parous and nulliparous women in Ghana

Background

Overweight and obesity are among the leading threats to global health because of their association with increased risk of morbidity and mortality. Much of the research on overweight and obesity among women largely generalize without due cognisance to differences in their reproductive history. This study explored differences in trends in overweight/obesity, and associated factors between parous and nulliparous women in Ghana.

Methods

Anthropometric measurements from three nationally representative Ghana Demographic and Health Surveys (2003, 2008 and 2014) were analysed using descriptive statistics and multivariate binary logistic regression.

Results

Over all, overweight/obesity increased between 2003 and 2014, with disproportionately higher rates among parous women (from about 30 % in 2003 to about 48 % in 2014) than nulliparous women (from about 15 % in 2003 to about 24 % in 2014). Age, wealth quintile and marital status were associated with overweight/obesity similarly in both women groups. However, there were variations in the association between parous and nulliparious women by educational level, type of locality, occupation and ethnicity.

Conclusion

The trend of overweight/obesity in Ghana warrants urgent national level public health attention to help curb the situation. Such interventions should be tailored bearing in mind the peculiar differences in associated factors between parous and nulliparous women.

Ghrelin acts as energy status sensor of male reproduction by modulating Sertoli cells glycolytic metabolism and mitochondrial bioenergetics

Ghrelin is a growth hormone-releasing peptide that has been suggested to interfere with spermatogenesis, though the underling mechanisms remain unknown. We studied the effect of ghrelin in human Sertoli cells (hSCs) metabolic phenotype. For that, hSCs were exposed to increasing concentrations of ghrelin (20, 100 and 500 pM) mimicking the levels reported in obese, normal weight, and severely undernourished individuals. The metabolite production/consumption was determined. The protein levels of key glycolysis-related transporters and enzymes were assessed. The lactate dehydrogenase (LDH) activity was measured. Mitochondrial complexes protein levels and mitochondria membrane potential were also measured. We showed that hSCs express the growth hormone secretagogue receptor. At the concentration present in the plasma of normal weight men, ghrelin caused a decrease of glucose consumption and mitochondrial membrane potential in hSCs, though LDH activity and lactate production remained unchanged, illustrating an alteration of glycolytic flux efficiency. Exposure of hSCs to levels of ghrelin found in the plasma of severely undernourished individuals decreased pyruvate consumption and mitochondrial complex III protein expression. All concentrations of ghrelin decreased alanine and acetate production by hSCs. Notably, the effects of ghrelin levels found in severely undernourished individuals were more pronounced in hSCs metabolic phenotype highlighting the importance of a proper eating behavior to maintain male reproductive potential. In conclusion, ghrelin acts as an energy status sensor for hSCs in a dose-dependent manner, showing an inverse association with the production of lactate, thus controlling the nutritional support of spermatogenesis.

Association of Fecundity With Changes in Adult Female Weight

OBJECTIVE

To evaluate whether weight change since age 18 years, current body mass index (BMI), and BMI at age 18 years are associated with fecundity.

METHODS

Our study included 1,950 women in the Nurses' Health Study 3 (2010-2014), a prospective cohort study, currently attempting pregnancy. Height, current weight, and weight at age 18 years were self-reported on the baseline questionnaire. Every 3-6 months thereafter, women reported the current duration of their pregnancy attempt. Multivariable-accelerated failure time models were used to estimate the time ratios and 95% confidence intervals (CIs).

RESULTS

For every 5-kg increase in body weight from age 18 years, current duration of pregnancy attempt increased by 5% (95% CI 3-7%). Compared with women who maintained weight, the adjusted median current duration was 0.5 months shorter in those who lost weight, 0.3 months longer for those who gained 4-9.9 kg and 10-19.9 kg, and 1.4 months longer for those who gained 20 kg or more (P trend ≤.001). The adjusted time ratio (95% CI) for a 5-kg/m increase in current BMI was 1.08 (1.04-1.12). After multivariable adjustment (including adjustment for current BMI), being underweight at age 18 years (BMI less than 18.5) was associated with a longer current duration of pregnancy attempt compared with normal-weight women (time ratio 1.25, 95% CI 1.07-1.47); however, being overweight or obese at age 18 years was not associated with fecundity.

CONCLUSION

Gaining weight in adulthood, being overweight or obese in adulthood, and being underweight at age 18 years were associated with a modest reduction in fecundity.

LEVEL OF EVIDENCE

II.

[Gender Obesity Report--Influence of obesity on Reproduction and Pregnancy]

Obesity influences reproduction in men and women at all ages. The increasing prevalence of obesity is associated with rising numbers of reproductive disorders in both sexes. Obesity influences menstrual cycle and ovulation irregularities, increases pregnancy complications and complication rates in assisted reproductive technologies in women and in men obesity is associated with lower semen parameters. Weight loss through lifestyle changes or bariatric surgery has positive effects on hormonal parameters and fertility in both men and women.

Paternal obesity negatively affects male fertility and assisted reproduction outcomes: a systematic review and meta-analysis

This systematic review investigated the effect of paternal obesity on reproductive potential. Databases searched were Pubmed, Ovid, Web of Science, Scopus, Cinahl and Embase. Papers were critically appraised by two reviewers, and data were extracted using a standardized tool. Outcomes were: likelihood of infertility, embryo development, clinical pregnancy, live birth, pregnancy viability, infant development, sperm; concentration, morphology, motility, volume, DNA fragmentation, chromatin condensation, mitochondrial membrane potential (MMP), and seminal plasma factors. Thirty papers were included, with a total participant number of 115,158. Obese men were more likely to experience infertility (OR = 1.66, 95% CI 1.53-1.79), their rate of live birth per cycle of assisted reproduction technology (ART) was reduced (OR = 0.65, 95% CI 0.44-0.97) and they had a 10% absolute risk increase of pregnancy non-viability. Additionally, obese men had an increased percentage of sperm with low MMP, DNA fragmentation, and abnormal morphology. Clinically significant differences were not found for conventional semen parameters. From these findings it can be concluded that male obesity is associated with reduced reproductive potential. Furthermore, it may be informative to incorporate DNA fragmentation analysis and MMP assessment into semen testing, especially for obese men whose results suggest they should have normal fertility.

Lack of association between leptin G-2548A polymorphisms and obesity risk: Evidence based on a meta-analysis

BACKGROUND

The prevalence of obesity is increasing in most industrialized and developing countries. We aimed to investigate the association between leptin (LEP) G-2548A polymorphisms and the risk of obesity.

METHODS

We searched the PubMed, Web of Science, and China National Knowledge Infrastructure databases for studies that evaluated the association between LEP G-2548A polymorphisms and obesity risk prior to March 2014. The odds ratio (OR) and its 95% confidence interval (95% CI) were calculated to estimate the risk of obesity. Meta-analysis of subgroup populations and different control sources was conducted using homozygote (AA vs. GG), allelic (A vs. G), dominant (AA+GA vs. GG), recessive (AA vs. GG+GA), and heterozygote (AG vs. GG) models. The heterogeneity of the studies was assessed using χ(2)-tests based on Q-statistics. The pooled ORs were calculated using a random-effects model if there was no heterogeneity; otherwise, a random-effects model was used. Two authors extracted the data independently. The funnel plots, Begg's and Egger's test were used to assess publication bias. All statistical analyses were performed using STATA 12.0 software.

RESULTS

Nine case-controlled publications that evaluated the association between LEP G-2548A polymorphisms and obesity risk, which included 2594 subjects (1235 obesity cases and 1359 controls), were included in our meta-analysis. No significant association between this polymorphism and obesity risk was observed (P>0.05). Significant heterogeneity was detected among the studies. The results of subgroup analysis according to ethnicity and different control groups suggested that LEP G-2548A polymorphisms might increase the obesity risk in African populations in the homozygote (AA vs. GG: OR=2.38, 95% CI=1.15-4.93, P=0.020) and recessive (AA vs. GG+GA: OR=2.03, 95% CI=1.34-3.06, P=0.001) models.

CONCLUSIONS

Overall, this meta-analysis indicated that LEP G-2548A polymorphisms are not associated with obesity risk, although significant associations were observed in the homozygote model (AA vs. GG) and the recessive model (AA vs. GG+GA) in Africa populations. Further studies are still needed to validate and confirm this association.

Prevalence of maternal preconception risk factors: an Italian multicenter survey

Objectives

Adequate preconception maternal health care is essential to reduce the risk of unwanted pregnancy outcomes and complications. Still, many women are exposed to a number of unhealthy risk factors both before and early in pregnancy. This study aimed to estimate the prevalence of a number of important preconception risk factors using data from a recent multicenter study in Italy.

Methods

The study was based on cross-sectional data from seven maternity clinics located in six different regions in Italy during the period January – June, 2012. Data on maternal preconception risk factors and characteristics were collected from 1,892 women who delivered healthy children and 320 women who were pregnant in the first trimester.

Results

About 97% of the women (n = 2,212) were exposed to one or more preconception risk factors. The overall prevalence of the most essential maternal risk factors was as follows: 41% had a age ≥35 years, 36% mistimed or did not intend their pregnancy, 58% did not request a preconception health visit to their doctor, 76% did not use folic acid supplements before pregnancy, 26% smoked at the last menstrual period, 19% had a body mass index ≥25 kg/m² before pregnancy, and 10% suffered from pregestational chronic diseases. The prevalence of certain variables varied between the maternity clinics.

Conclusions

Many Italian women are exposed to a number of preconception risk factors that have been associated with adverse pregnancy complications and outcomes. More effective intervention programs to improve preconception health in Italian women are strongly needed.

Male fertility is reduced by chronic intermittent hypoxia mimicking sleep apnea in mice

STUDY OBJECTIVES

Obstructive sleep apnea (OSA) is characterized by intermittent hypoxia and oxidative stress. However, it is unknown whether intermittent hypoxia mimicking OSA modifies male fertility. We tested the hypothesis that male fertility is reduced by chronic intermittent hypoxia mimicking OSA in a mouse model.

DESIGN

Case-control comparison in a murine model.

SETTING

University research laboratory.

PARTICIPANTS

Eighteen F1 (C57BL/6xCBA) male mice.

INTERVENTIONS

Mice were subjected to a pattern of periodic hypoxia (20 sec at 5% O2 followed by 40 sec of room air) 6 h/day for 60 days or normoxia. After this period, mice performed a mating trial to determine effective fertility by assessing the number of pregnant females and fetuses.

MEASUREMENTS AND RESULTS

After euthanasia, oxidative stress in testes was assessed by measuring the expression of glutathione peroxidase 1 (Gpx1) and superoxide dismutase-1 (Sod1) by reverse-transcription polymerase chain reaction. Sperm motility was determined by Integrated Semen Analysis System (ISAS). Intermittent hypoxia significantly increased testicular oxidative stress, showing a reduction in the expression of Gpx1 and Sod1 by 38.9% and 34.4%, respectively, as compared with normoxia (P < 0.05). Progressive sperm motility was significantly reduced from 27.0 ± 6.4% in normoxia to 12.8 ± 1.8% in the intermittent hypoxia group (P = 0.04). The proportion of pregnant females and number of fetuses per mating was significantly lower in the intermittent hypoxia group (0.33 ± 0.10 and 2.45 ± 0.73, respectively) than in normoxic controls (0.72 ± 0.16 and 5.80 ± 1.24, respectively).

CONCLUSIONS

These results suggest that the intermittent hypoxia associated with obstructive sleep apnea (OSA) could induce fertility reduction in male patients with this sleep breathing disorder.

Early developmental conditioning of later health and disease: physiology or pathophysiology?

Extensive experimental animal studies and epidemiological observations have shown that environmental influences during early development affect the risk of later pathophysiological processes associated with chronic, especially noncommunicable, disease (NCD). This field is recognized as the developmental origins of health and disease (DOHaD). We discuss the extent to which DOHaD represents the result of the physiological processes of developmental plasticity, which may have potential adverse consequences in terms of NCD risk later, or whether it is the manifestation of pathophysiological processes acting in early life but only becoming apparent as disease later. We argue that the evidence suggests the former, through the operation of conditioning processes induced across the normal range of developmental environments, and we summarize current knowledge of the physiological processes involved. The adaptive pathway to later risk accords with current concepts in evolutionary developmental biology, especially those concerning parental effects. Outside the normal range, effects on development can result in nonadaptive processes, and we review their underlying mechanisms and consequences. New concepts concerning the underlying epigenetic and other mechanisms involved in both disruptive and nondisruptive pathways to disease are reviewed, including the evidence for transgenerational passage of risk from both maternal and paternal lines. These concepts have wider implications for understanding the causes and possible prevention of NCDs such as type 2 diabetes and cardiovascular disease, for broader social policy and for the increasing attention paid in public health to the lifecourse approach to NCD prevention.

Perception of weight status and its impact on gestational weight gain in an urban population

To examine the association between actual and perceived overweight/obese status and excess gestational weight gain (GWG). As part of an infant feeding trial, multi-ethnic lower and moderate income women-completed a checklist of current health conditions, including "overweight/obesity," "asthma," and "hypertension" while pregnant. Odds of excessive GWG per the Institute of Medicine guidelines in 'accurate' versus 'inaccurate' reporters, by overweight status were analyzed with multivariate logistic regression for women with pre-or early pregnancy BMIs of ≥18.5. 775 women met study criteria. Just 21 % (n = 107) of overweight/obese women accurately identified their weight status, compared to >90 % accurate report of documented hypertension or asthma. Compared to normal-weight accurate reporters, the adjusted odds of excessive GWG in overweight/obese women was 2.3 (95 % CI 1.4, 3.7) in accurate reporters, and 2.5 (95 % CI 1.7, 3.4) in inaccurate reporters. Overweight/obesity is associated with excessive GWG, but this risk is not modified by inaccurate reporting/perception of weight-status.

Non-linear associations between stature and mate choice characteristics for American men and their spouses

OBJECTIVES

Although male height is positively associated with many aspects of mate quality, average height men attain higher reproductive success in US populations. We hypothesize that this is because the advantages associated with taller stature accrue mainly from not being short, rather than from being taller than average. Lower fertility by short men may be a consequence of their and their partner's lower scores on aspects of mate quality. Taller men, although they score higher on mate quality compared to average height men, may have lower fertility because they are more likely to be paired with taller women, who are potentially less fertile.

METHODS

We analyzed data from The Integrated Health Interview Series (IHIS) of the United States (N = 165,606). Segmented regression was used to examine patterns across the height continuum.

RESULTS

On all aspects of own and partner quality, shorter men scored lower than both average height and taller men. Height more strongly predicted these aspects when moving from short to average height, than when moving from average to taller heights. Women of a given height who scored lower on mate quality also had shorter partners.

CONCLUSIONS

Shorter men faced a double disadvantage with respect to both their own mate quality and that of their spouses. Scores of taller men were only marginally higher than those of average height men, suggesting that being tall is less important than not being short. Although effect sizes were small, our results may partly explain why shorter and taller men have lower fertility than those of average stature.

Body mass index at age 20 and subsequent childbearing: the Adventist Health Study-2

BACKGROUND

Some epidemiological, clinical, and laboratory studies suggest that underweight and obesity impact fertility.

METHODS

This is cross-sectional study of 33,159 North American Adventist women, who were nulliparous at age 20 years and who, as a group, have a healthy lifestyle. Logistic regression analysis was used to assess how body mass index (BMI, kg/m(2)) at age 20 was related to never becoming pregnant, never giving birth to a living child, or not giving birth to a second or third child.

RESULTS

A total of 4954 (15%) of the women reported never becoming pregnant (nulligravidity) and 7461 (23%) women remained nulliparous. Underweight (BMI<18.5 kg/m(2)) at age 20 was associated with approximately 13% increased risk of nulligravidity or nulliparity. Women with BMI≥32.5 kg/m(2) when aged 20 had 2.5 (95% CI: 2.0, 3.1) times increased odds of nulliparity compared to women with BMI 20-24.9 kg/m(2). Increased risk was found for all groups of overweight women (BMI≥25 kg/m(2)). However, if the women gave birth to one live child after age 20, BMI≥32.5 kg/m(2) at age 20 had less impact (OR 1.6 [95% CI: 1.2, 2.2]) on the likelihood of not delivering a second child. In women who delivered two living children, obesity at age 20 had no bearing on the odds of having a third child.

CONCLUSIONS

Obesity and, to a lesser extent, underweight at age 20 increases the nulliparity rate. The results underscore the importance of a healthy weight in young women.

Obesity at age 20 and the risk of miscarriages, irregular periods and reported problems of becoming pregnant: the Adventist Health Study-2

In a group of 46,000 North-American Adventist women aged 40 and above, we investigated the relationships between body mass index (BMI, kg/m²) at age 20 and the proportion of women who reported at least one miscarriage, periods with irregular menstruation or failing to become pregnant even if trying for more than one straight year. Approximately 31, 14 and 17 %, respectively, reported the three different problems related to reproduction. Positive age- and marital status adjusted relationships were found between BMI at age 20 and periods with irregular menstruation or failing to become pregnant even if trying for more than 1 year, but not with the risk of miscarriages. Women with BMI ≥ 32.5 kg/m² when aged 20 had approximately 2.0 (95 % CI: 1.6, 2.4) and 1.5 (95 % CI: 1.3, 1.9) higher odds for irregular periods or failing to get pregnant, respectively, than women with BMI in the 20–24.9 kg/m² bracket. These relationships were consistently found in a number of strata of the population, including the large proportion of the women who never had smoked or never used alcohol. Underweight (BMI < 18.5 kg/m²) when aged 20 marginally (approximately 15 %) increased the risk of failing to get pregnant within a year. Thus, obesity at age 20 increases the risk of reporting some specific reproductive problems, but not the risk of miscarriages.

Impact of body mass index on seminal oxidative stress

Male obesity has been linked with a reduction in sperm concentration and motility, an increase in sperm DNA damage and changes in reproductive hormones. Recent large observational studies have linked male obesity with a reduced chance of becoming a father. One of the potential underlying pathological mechanisms behind diminished reproductive performance in obese men is sperm oxidative stress. The primary aim of this study was to determine if sperm oxidative stress was more common in obese/overweight men. A total of 81 men had their body mass index (BMI) correlated with seminal reactive oxygen species (ROS) production (Nitro Blue Tetrazolium assay), sperm DNA damage (TUNEL), markers of semen inflammation (CD45, seminal plasma PMN elastase and neopterin concentration) and routine sperm parameters, together with reproductive hormones. The principal finding from this study was that oxidative stress did increase with an increase in BMI, primarily due to an increase in seminal macrophage activation. However, the magnitude of this increase was small and only of minor clinical significance as there was no associated decline in sperm DNA integrity or sperm motility with increasing ROS production. Increased BMI was also found to be significantly linked with a fall in sperm concentration and serum testosterone, and an increase in serum oestradiol.