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

Anti-Obesity Drug Delivery Systems: Recent Progress and Challenges

Obesity has reached an epidemic proportion in the last thirty years, and it is recognized as a major health issue in modern society now with the possibility of serious social and economic consequences. By the year 2030, nearly 60% of the global population may be obese or overweight, which emphasizes a need for novel obesity treatments. Various traditional approaches, such as pharmacotherapy and bariatric surgery, have been utilized in clinical settings to treat obesity. However, these methods frequently show the possibility of side effects while remaining ineffective. There is, therefore, an urgent need for alternative obesity treatments with improved efficacy and specificity. Polymeric materials and chemical strategies are employed in emerging drug delivery systems (DDSs) to enhance therapy effectiveness and specificity by stabilizing and controlling the release of active molecules such as natural ingredients. Designing DDSs is currently a top priority research objective with an eye towards creating obesity treatment approaches. In reality, the most recent trends in the literature demonstrate that there are not enough in-depth reviews that emphasize the current knowledge based on the creation and design of DDSs for obesity treatment. It is also observed in the existing literature that a complex interplay of different physical and chemical parameters must be considered carefully to determine the effectiveness of the DDSs, including microneedles, for obesity treatment. Additionally, it is observed that these properties depend on how the DDS is synthesized. Although many studies are at the animal-study stage, the use of more advanced DDS techniques would significantly enhance the development of safe and efficient treatment approaches for obese people in the future. Considering these, this review provides an overview of the current anti-obesity treatment approaches as well as the conventional anti-obesity therapeutics. The article aims to conduct an in-depth discussion on the current trends in obesity treatment approaches. Filling in this knowledge gap will lead to a greater understanding of the safest ways to manage obesity.

Transdermal Drug Delivery Systems and Their Use in Obesity Treatment

Transdermal drug delivery (TDD) has recently emerged as an effective alternative to oral and injection administration because of its less invasiveness, low rejection rate, and excellent ease of administration. TDD has made an important contribution to medical practice such as diabetes, hemorrhoids, arthritis, migraine, and schizophrenia treatment, but has yet to fully achieve its potential in the treatment of obesity. Obesity has reached epidemic proportions globally and posed a significant threat to human health. Various approaches, including oral and injection administration have widely been used in clinical setting for obesity treatment. However, these traditional options remain ineffective and inconvenient, and carry risks of adverse effects. Therefore, alternative and advanced drug delivery strategies with higher efficacy and less toxicity such as TDD are urgently required for obesity treatment. This review summarizes current TDD technology, and the main anti-obesity drug delivery system. This review also provides insights into various anti-obesity drugs under study with a focus on the recent developments of TDD system for enhanced anti-obesity drug delivery. Although most of presented studies stay in animal stage, the application of TDD in anti-obesity drugs would have a significant impact on bringing safe and effective therapies to obese patients in the future.

Associations of childhood adiposity with menstrual irregularity and polycystic ovary syndrome in adulthood: the Childhood Determinants of Adult Health Study and the Bogalusa Heart Study

STUDY QUESTION

Is high adiposity in childhood associated with menstrual irregularity and polycystic ovary syndrome (PCOS) in later life?

SUMMARY ANSWER

Overall, greater childhood BMI was associated with menstrual irregularity, and greater childhood BMI and waist/height ratio (WHtR) in white but not black participants were associated with PCOS in adulthood.

WHAT IS KNOWN ALREADY

Increased childhood BMI has been associated with irregular menstrual cycles and PCOS symptoms in adulthood in two longitudinal population-based studies, but no study has reported on associations with childhood abdominal obesity. Few studies have investigated whether there are racial differences in the associations of adiposity with PCOS though there has been some suggestion that associations with high BMI may be stronger in white girls than in black girls.

STUDY DESIGN, SIZE, DURATION

The study included 1516 participants (aged 26-41 years) from the Australian Childhood Determinants of Adult Health study (CDAH) and 1247 participants (aged 26-57 years) from the biracial USA Babies substudy of the Bogalusa Heart Study (BBS) who were aged 7-15 years at baseline. At follow-up, questions were asked about menstruation (current for CDAH or before age 40 years for BBS), ever having had a diagnosis of PCOS and symptoms of PCOS.

PARTICIPANTS/MATERIALS, SETTING, METHODS

In CDAH, a single childhood visit was conducted in 1985. In BBS, multiple childhood visits occurred from 1973 to 2000 and race was reported (59% white; 41% black). In childhood, overweight and obesity were defined by international age-sex-specific standards for BMI and WHtR was considered as an indicator of abdominal obesity. Multilevel mixed-effects Poisson regression estimated relative risks (RRs) adjusting for childhood age, highest parental and own education and age at menarche.

MAIN RESULTS AND THE ROLE OF CHANCE

The prevalence of childhood obesity was 1.1% in CDAH and 7.5% in BBS. At follow-up, menstrual irregularity was reported by 16.7% of CDAH and 24.5% of BBS participants. The prevalence of PCOS was 7.4% in CDAH and 8.0% in BBS participants. In CDAH, childhood obesity was associated with menstrual irregularity (RR = 2.84, 95% CI: 1.63-4.96) and PCOS (RR = 4.05, 95% CI: 1.10-14.83) in adulthood. With each 0.01 unit increase in childhood WHtR there was a 6% (95% CI: 1-11%) greater likelihood of PCOS. Overall, in BBS, childhood obesity was associated with increased risk of menstrual irregularity (RR = 1.44, 95% CI: 1.08-1.92) in adulthood. Significant interaction effects between race and childhood adiposity were detected in associations with PCOS. In BBS white participants, childhood obesity was associated with PCOS (RR = 2.93, 95% CI: 1.65-5.22) and a 0.01 unit increase in childhood WHtR was associated with an 11% (95% CI: 5-17%) greater likelihood of PCOS in adulthood. In BBS black participants, no statistically significant associations of childhood adiposity measures with PCOS were observed.

LIMITATIONS, REASONS FOR CAUTION

The classification of menstrual irregularity and PCOS was based on self-report by questionnaire, which may have led to misclassification of these outcomes. However, despite the limitations of the study, the prevalence of menstrual irregularity and PCOS in the two cohorts was consistent with the literature. While the study samples at baseline were population-based, loss to follow-up means the generalizability of the findings is uncertain.

WIDER IMPLICATIONS OF THE FINDINGS

Greater childhood adiposity indicates a higher risk of menstrual irregularity and PCOS in adulthood. Whether this is causal or an early indicator of underlying hormonal or metabolic disorders needs clarification. The stronger associations of adiposity with PCOS in white than black participants suggest that there are racial differences in childhood adiposity predisposing to the development of PCOS and other environmental or genetic factors are also important.

STUDY FUNDING/COMPETING INTEREST(S)

The CDAH study was supported by grants from the Australian National Health and Medical Research Council (grants 211316, 544923 and 1128373). The Bogalusa Heart Study is supported by US National Institutes of Health grants R01HD069587, AG16592, HL121230, HD032194 and P50HL015103. No competing interests existed.

Substantial Weight Gain in Adulthood Is Associated with Lower Probability of Live Birth Following Assisted Reproduction

BACKGROUND

Overweight and obesity among women have been associated with lower success of assisted reproduction technologies (ARTs). However, the relation of adolescent body weight and adult weight change to ART outcomes is not well understood.

OBJECTIVE

Our objective was to evaluate the associations of female BMI (in kg/m2) at 18 y and weight change from 18 y to current age with ART outcomes.

METHODS

We included 486 women in a prospective cohort at the Massachusetts General Hospital Fertility Center (2004-2018) who underwent 863 ART cycles. At study entry, height and weight were measured by research personnel. Women recalled their weight at 18 y. Restricted cubic splines were used to evaluate the associations between BMI at 18 y and weight change since 18 y and ART outcomes adjusting for age, race, education, smoking, and height and accounting for the correlated cycles within women.

RESULTS

Women had a median (range) BMI of 20.6 (14.8 to 36.4) at 18 y and 23.3 (16.1 to 45.8) at study entry. The median (range) weight change since 18 y was 7.4 kg (-12.1 to 60.1 kg). There was no association between BMI at 18 y and clinical ART outcomes. Long-term weight change had a nonlinear association with live birth such that higher weight gain since 18 y (particularly ≥15 kg) and weight loss were both associated with lower odds of live birth. The negative association between weight change and live birth was stronger in women ≥22.5 kg/m2 at 18 y such that each 10-kg increase was associated with a 30% (6%, 48%) lower odds of live birth.

CONCLUSIONS

Weight gain in adulthood is negatively associated with ART success, particularly among women who were heavier at 18 y. These results add to the growing literature supporting the benefits of preventing weight gain in adulthood on female fertility.

Relationships between menstrual status and obesity phenotypes in women: a cross-sectional study in northern China

BACKGROUND

One of most important concerns of postmenopausal women is obesity. The relationships between menstruation status and obesity phenotypes are unclear. This study aimed to assess the associations between menstrual status and different obesity phenotypes in women.

METHODS

In total, 5373 women aged ≥40 years were recruited from the Jidong and Kailuan communities. Basic information was collected via clinical examination, laboratory testing and standardized questionnaires. The women were stratified into the following three groups: menstrual period, menopausal transition period and postmenopausal period. General obesity was defined as a body mass index (BMI) of ≥28 kg/m². Central obesity was defined as a waist-to-hip ratio (WHR) of > 0.85. Visceral obesity was defined as the presence of nonalcoholic fatty liver disease (NAFLD) and increased pericardial fat volume (PFV).

RESULTS

The numbers of women in the menstrual, menopausal transition, and postmenopausal periods were 2807 (52.2%), 675 (12.6%) and 1891 (35.2%), respectively. The adjusted odds ratio (OR) and 95% confidence interval (CI) for central obesity among women in the menopausal transition and postmenopausal periods compared with women in the menstrual period were 0.99 (0.82-1.19) and 1.52 (1.26-1.84), respectively. The OR for NAFLD among postmenopausal women was 1.78 (1.44-2.20). The adjusted β-coefficient (standard error, SE) for PFV among postmenopausal women was 41.25 (7.49). The adjusted OR for general obesity among postmenopausal women was 1.01 (0.77-1.34).

CONCLUSIONS

This study demonstrated that menopause is an independent risk factor for central and visceral obesity but not general obesity.

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

Background

Extreme pre-pregnancy body mass index (BMI) values have been associated with reduced fecundability and prolonged time to pregnancy in previous studies. However, the effect in fertile couples is unclear.

Objectives

This study aimed to evaluate the association between pre-pregnancy BMI and fecundability, measured as time to pregnancy (TTP), among couples that achieved pregnancy within 1 year.

Methods

This was a retrospective cohort study of 50,927 couples wishing to conceive, enrolled in the National Free Preconception Health Examination Project (NFPHEP) in Chongqing, China, during 2012–2016. Participants’ weight and height were measured by NFPHEP-trained preconception guidance physicians. TTP measured in months was used to determine subfecundity (TTP >6 months). The strength of association between BMI and TTP/subfecundity was measured with fecundability odds ratios (FOR)/odds ratios (OR) and their corresponding 95% confidence intervals (CI), calculated with Cox and logistic regression analysis. We used restricted cubic spline regression (RCS) to test the observed FOR trends.

Results

Compared to women with normal BMI, women with pre-pregnancy overweight/obesity had longer TTP (FOR = 0.96, 95% CI: 0.94–0.99) and increased risk of subfecundity (OR = 1.08, 95% CI: 1.00–1.17). There was no association between TTP and male BMI. RCS trends varied when data were stratified by male pre-pregnancy BMI, with the greatest change detected in pre-pregnancy underweight men.

Conclusions

Pre-pregnancy overweight/obesity was associated with longer TTP and subfecundity among women who became pregnant within 1 year; this effect was likely mediated by their partners’ pre-pregnancy BMI. These findings indicate that BMI could affect fecundability, independently of affecting the risk of sterility. Advice on weight management and maintaining healthy weight should be included in couples’ preconception guidance.

Obesity and Reproduction

OBJECTIVE

To provide a comprehensive review and evidence-based recommendations for the delivery of fertility care to women with obesity.

OUTCOMES

The impact of obesity on fertility, fertility treatments, and both short and long-term maternal fetal outcomes was carefully considered.

EVIDENCE

Published literature was reviewed through searches of MEDLINE and CINAHL using appropriate vocabulary and key words. Results included systematic reviews, clinical trials, observational studies, clinical practice guidelines, and expert opinions.

VALUES

The Canadian Fertility & Andrology Society (CFAS) is a multidisciplinary, national non-profit society that serves as the voice of reproductive specialists, scientists, and allied health professionals working in the field of assisted reproduction in Canada. The evidence obtained for this guideline was reviewed and evaluated by the Clinical Practice Guideline (CPG) Committee of the CFAS under the leadership of the principal authors.

BENEFITS, HARMS, AND COSTS

The implementation of these recommendations should assist clinicians and other health care providers in counselling and providing reproductive care to women with obesity.

VALIDATION

This guideline and its recommendations have been reviewed and approved by the membership, the CPG Committee and the Board of Directors of the CFAS.

SPONSORS

Canadian Fertility & Andrology Society.

RECOMMENDATIONS

Twenty-one evidence based recommendations are provided. These recommendations specifically evaluate the impact of obesity on natural fertility, fertility treatments, and maternal-fetal outcomes. Strategies to lose weight and BMI cut-offs are also addressed.

Vitamin D and Obesity: Two Interacting Players in the Field of Infertility

Obesity plays an important role in human fertility in both genders. The same is true for vitamin D, for which accumulating evidence from observational human studies suggests a key role for both male and female fertility. In the latter case, however, robust data from relevant interventional studies are currently lacking. It is also not clear whether obesity and vitamin D deficiency, besides their independent effect on human infertility, act in synergy. Several pathogenetic mechanisms may be proposed as a linkage between vitamin D deficiency and obesity, with respect to infertility. In any case, the independent contribution of vitamin D deficiency in obese infertile states needs to be proven in interventional studies focusing on either vitamin D supplementation in obese or weight loss strategies in vitamin D-deficient infertile patients.

Low-Dose Urinary Human Chorionic Gonadotropin Is Effective for Oocyte Maturation in In Vitro Fertilization/ Intracytoplasmic Sperm Injection Cycles Independent of Body Mass Index

BACKGROUND

Currently, there is no agreement on the optimal urinary derived human chorionic gonadotropin (u-hCG) dose requirement for initiating final oocyte maturation prior to oocyte collection in in vitro fertilization (IVF), but doses that range from 2500- 15000 IU have been used. We intended to determine whether low dose u-hCG was effective for oocyte maturation in IVF/intracytoplasmic sperm injection (ICSI) cycles independent of body mass index (BMI).

MATERIALS AND METHODS

We retrospectively evaluated a cohort of 295 women who underwent their first IVF/ICSI cycles between January 2003 and December 2010 at the Division of Reproductive Endocrinology and Infertility, Wayne State University, Detroit, MI, USA. Treatment cycles were divided into 3 groups based on BMI (kg/ m²): <25 (n=136), 25- <30 (n=84), and ≥30 (n=75) women. Patients received 5000, 10000 or 15000 IU u-hCG for final maturation prior to oocyte collection. The primary outcome was clinical pregnancy rates (CPRs) and secondary outcome was live birth rates (LBRs).

RESULTS

Only maternal age negatively impacted (P<0.001) CPR [odds ratio (OR=0.85, confidence interval (CI: 0.79-0.91)] and LBR (OR=0.84, CI: 0.78-0.90).

CONCLUSION

Administration of lower dose u-hCG was effective for oocyte maturation in IVF and did not affect the CPRs and LBRs irrespective of BMI. Women's BMI need not be taken into consideration in choosing the appropriate dose of u-hCG for final oocyte maturation prior to oocyte collection in IVF. Only maternal age at the time of IVF negatively influenced CPRs and LBRs in this study.

Association between the CLOCK gene 3111 T > C polymorphism and an irregular menstrual cycle in Korean adolescents

The menstrual cycle is an example of a human infradian rhythm, but an altered sleep-wake cycle or a disrupted circadian rhythm can change the regularity of the menstrual cycle. In this study, we investigated whether an irregular menstrual cycle is associated with polymorphisms in the CLOCK (3111T > C) and/or PER3 (variable number tandem repeat, VNTR) genes, which are known to have an impact on the circadian rhythm. One hundred ninety-seven postmenarchal, adolescent girls from two girls' high schools in Seoul, Korea, were studied. All participants were requested to complete the Perceived Stress Scale (PSS), the State-Trait Anxiety Inventory (STAI), and the Beck Depression Inventory (BDI) to assess the emotional distress that might cause menstrual irregularity. Every participant donated a blood sample from which DNA was extracted and genotyped for the CLOCK 3111T > C and PER3 VNTR polymorphisms. A significant association was found between the CLOCK 3111T > C genotype and irregular menstrual cycles. Subjects with the 3111T > C genotype had a high risk of an irregular menstrual cycle compared with 3111T/T homozygous subjects (odds ratio [OR] = 2.88; 95% confidence interval [CI]: 1.26-6.55). When multivariate logistic regression analysis was performed to adjust for age, PSS, STAI, BDI and BMI, subjects with the 3111T > C polymorphism showed a significantly increased OR for irregular menstrual cycles (OR = 3.09; 95% CI: 1.32-7.21). There was no significant association between the PER3 VNTR polymorphism and the irregularity of the menstrual cycle (p > 0.05). The results of this study suggest that the CLOCK 3111T > C polymorphism could be an independent risk factor for irregular menstrual cycles, irrespective of psychological distress and endocrine or metabolic conditions, and could be used as a molecular marker for gynecological studies on this aspect.

[Impact of maternal overnutrition on the periconceptional period]

Overnutrition may lead to obesity. Maternal obesity may affect fertility not only via anovulation, but also through direct effects on oocytes and preimplantation embryos, indicating that the periconceptional period is sensitive to conditions of overnutrition. The periconceptional period includes from folliculogenesis to implantation. Animal model studies suggest that oocytes derived from obese females usually have a small size and mitochondrial abnormalities. These disruptions are probably induced by changes in the components of the ovarian follicular fluid. Experimental evidence also suggests that obesity may affect the microenvironment in oviducts and uterus, resulting in development of preimplantation embryos with reduced cell numbers and up-regulation of proinflammatory genes. However, further research is needed for in-depth characterization of the effects of maternal obesity during the periconceptional period.

Early origins of chronic obstructive lung diseases across the life course

Chronic obstructive lung diseases, like asthma and chronic obstructive pulmonary disease, have high prevalences and are a major public health concern. Chronic obstructive lung diseases have at least part of their origins in early life. Exposure to an adverse environment during critical periods in early life might lead to permanent developmental adaptations which results in impaired lung growth with smaller airways and lower lung volume, altered immunological responses and related inflammation, and subsequently to increased risks of chronic obstructive lung diseases throughout the life course. Various pathways leading from early life factors to respiratory health outcomes in later life have been studied, including fetal and early infant growth patterns, preterm birth, maternal obesity, diet and smoking, children's diet, allergen exposure and respiratory tract infections, and genetic susceptibility. Data on potential adverse factors in the embryonic and preconception period and respiratory health outcomes are scarce. Also, the underlying mechanisms how specific adverse exposures in the fetal and early postnatal period lead to chronic obstructive lung diseases in later life are not yet fully understood. Current studies suggest that interactions between early environmental exposures and genetic factors such as changes in DNA-methylation and RNA expression patterns may explain the early development of chronic obstructive lung diseases. New well-designed epidemiological studies are needed to identify specific critical periods and to elucidate the mechanisms underlying the development of chronic obstructive lung disease throughout the life course.

The Generation R Study: Biobank update 2015

The Generation R Study is a population-based prospective cohort study from fetal life until adulthood. The study is designed to identify early environmental and genetic causes and causal pathways leading to normal and abnormal growth, development and health from fetal life, childhood and young adulthood. In total, 9,778 mothers were enrolled in the study. Data collection in children and their parents include questionnaires, interviews, detailed physical and ultrasound examinations, behavioural observations, Magnetic Resonance Imaging and biological samples. Efforts have been conducted for collecting biological samples including blood, hair, faeces, nasal swabs, saliva and urine samples and generating genomics data on DNA, RNA and microbiome. In this paper, we give an update of the collection, processing and storage of these biological samples and available measures. Together with detailed phenotype measurements, these biological samples provide a unique resource for epidemiological studies focused on environmental exposures, genetic and genomic determinants and their interactions in relation to growth, health and development from fetal life onwards.

Female obesity and infertility

Infertility affects one in seven couples, and its rate is on the increase. Ovulatory defects and unexplained causes account for >50% of infertile aetiologies. It is postulated that a significant proportion of these cases are either directly or indirectly related to obesity. The prevalence of overweight and obese men and women has topped 50% in some developed countries. Obesity is on the increase worldwide; in turn, the consequences in terms of the associated morbidity and mortality have also been increasing. Obesity is associated with various reproductive sequelae including anovulation, subfertility and infertility, increased risk of miscarriage and poor neonatal and maternal pregnancy outcomes. Thus, the combination of infertility and obesity poses some very real challenges in terms of both the short- and long-term management of these patients. The mechanism with which obesity impacts female reproductive function is summarised in this review.

Prepregnancy and early adulthood body mass index and adult weight change in relation to fetal loss

OBJECTIVE

To examine prospectively the relationships of prepregnancy body mass index (BMI), BMI at age 18 years, and weight change since age 18 years with risk of fetal loss.

METHODS

Our prospective cohort study included 25,719 pregnancies reported by 17,027 women in the Nurses' Health Study II between 1990 and 2009. In 1989, height, current weight, and weight at age 18 years were self-reported. Current weight was updated every 2 years thereafter. Pregnancies were self-reported, with case pregnancies lost spontaneously and comparison pregnancies ending in ectopic pregnancy, induced abortion, or live birth.

RESULTS

Incident fetal loss was reported in 4,494 (17.5%) pregnancies. Compared with those of normal BMI, the multivariate relative risks of fetal loss were 1.07 (95% CI [confidence interval] 1.00-1.15) for overweight women, 1.10 (95% CI 0.98-1.23) for class I obese women, and 1.27 (95% CI 1.11-1.45) for class II and class III obese women (P trend ≤ .001). Body mass index at age 18 years was not associated with fetal loss (P trend=.59). Compared with women who maintained a stable weight (± 4 kg) between age 18 years and before pregnancy, women who lost weight had a 20% (95% CI 9-29%) lower risk of fetal loss. This association was stronger among women who were overweight at age 18 years.

CONCLUSION

Being overweight or obese before pregnancy was associated with higher risk of fetal loss. In women overweight or obese at age 18 years, losing 4 kg or more was associated with a lower risk of fetal loss.

LEVEL OF EVIDENCE

: II.

Soy isoflavone intake and the likelihood of ever becoming a mother: the Adventist Health Study-2

Objectives

As little is known about the possible relationship between the intake of phytoestrogens and female fertility, we investigated the relationship between soy isoflavone intake and the risk of nulliparity and nulligravidity.

Methods

A cross-sectional study of 11,688 North American Adventist women aged 30–50 years old with data regarding childbearing. These women were, as a group, characterized by a high proportion (54%) of vegetarians and a healthy lifestyle with a very low prevalence of smoking and alcohol use.

Results

The mean isoflavone intake (17.9 mg per day) was very high compared to other Western populations. Only 6% of the women indicated no intake of isoflavones. We found, after adjustment for age, marital status, and educational level, an inverse relationship (P=0.05) between isoflavone intake and the likelihood of ever having become a mother. In women with high (≥40 mg/day) isoflavone intake (12% of this group of women), the adjusted lifetime probability of giving birth to a live child was reduced by approximately 3% (95% CI: 0, 7) compared to women with low (<10 mg/day) intake. No relationships were found between the isoflavone intake and parity or age at first delivery in parous women. A similar inverse relationship (P=0.03) was found between the isoflavone intake and the risk of nulligravidity with a 13% (95% CI: 2, 26) higher risk of never have been pregnant in women with high (≥40 mg/day) isoflavone intake. These relationships were found mainly in women who reported problems becoming pregnant.

Conclusion

The findings suggest that a high dietary isoflavone intake may have significant impact on fertility.

The Rotterdam Study: 2014 objectives and design update

The Rotterdam Study is a prospective cohort study ongoing since 1990 in the city of Rotterdam in The Netherlands. The study targets cardiovascular, endocrine, hepatic, neurological, ophthalmic, psychiatric, dermatological, oncological, and respiratory diseases. As of 2008, 14,926 subjects aged 45 years or over comprise the Rotterdam Study cohort. The findings of the Rotterdam Study have been presented in over a 1,000 research articles and reports (see www.erasmus-epidemiology.nl/rotterdamstudy ). This article gives the rationale of the study and its design. It also presents a summary of the major findings and an update of the objectives and methods.

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.