Breastfeeding and timing of pubertal onset in girls: a multiethnic population-based prospective cohort study

Association between infant breastfeeding practices and timing of peak height velocity: A nationwide longitudinal survey in Japan

BACKGROUND

Several studies have discovered an association between infant feeding practices and puberty timing; however, most have involved female cohorts. We investigated the association between infant feeding practices and the timing of peak height velocity in boys and girls.

METHODS

Data on infant feeding methods and anthropometric measurements were collected from a nationwide Japanese birth cohort study. The age at peak height velocity (APV, years) was estimated and compared. Subsequently, the effects of breastfeeding duration were analyzed.

RESULTS

Of the 13,074 eligible participants, 650, 9455, and 2969 were formula-, mixed-, and exclusively breastfed, respectively. Among girls, the mean APV was significantly later in the mixed-fed (standardized regression coefficient (β): 0.094, 95% confidence interval (CI): 0.004-0.180) and exclusively breastfed (β: 0.150, 95% CI: 0.056-0.250) groups than in the formula-fed group. Among boys, the mean APV was not significantly different among the three groups; however, a sensitivity analysis that excluded preterm birth revealed more significantly delayed APV in the breastfed-only group compared to the formula-fed group. Furthermore, a multiple linear regression model revealed that a longer breastfeeding period was associated with later APV.

CONCLUSIONS

Infant breastfeeding practices can affect the timing of peak height velocity in both boys and girls.

IMPACT

Several studies have discovered an association between infant feeding practices and puberty timing; however, most have involved female cohorts. Age at peak height velocity, derived from longitudinal height measurements, is a useful marker of secondary sexual maturity milestones in boys and girls. A Japanese birth cohort study revealed that breastfed children had a later age at peak height velocity than their formula-fed counterparts; this was more prominent among girls than boys. Furthermore, a duration-effect relationship was observed, where longer breastfeeding duration was associated with a later age at peak height velocity.

Breast and Formula Milk and Early Puberty Onset

Nutrients have an enormous impact on many hormonal systems and aspects of health, and nutrition status is a crucial regulator of growth and pubertal development in children and adolescents. In this narrative review, we explore the connection between these feeding methods and the timing of puberty to provide a clearer understanding of how infant nutrition might contribute to the early development of puberty. Puberty is a key stage in the transition from childhood to adulthood and the timing of puberty represents a significant biological milestone of growth. Breast milk seems to have a pivotal role in puberty onset, mainly due to its dynamism, which shape indirectly the gut microbiota in early life, besides direct exposure of the baby to the milk microbiota through gut-breast axis. Concerning breast and formula milk and their effects on the onset of puberty, a protective role of the former occurs. As for the potential harmful effects of soy-based formulas and the isoflavones that they contain, the studies reported demonstrate conflicting opinions, underlining the need for further research on this topic. A healthy and well-nourished diet from the earliest stages of life has significant preventive potential for overall well-being, reducing the risk of many health problems later in life.

A systematic review on maternal and perinatal factors influencing breast development

BACKGROUND

A secular trend towards earlier age at menarche has been reported, but the trend in breast development is less clear. We reviewed the evidence on the relationship between in utero and early life events and breast onset/development.

METHODS

Eligible studies were identified in PubMed and Embase databases. We selected studies in which female human exposure during fetal or the first years of life was measured or estimated, and associations with breast onset or development were evaluated.

RESULTS

Of the 49 cohort studies and 5 cross-sectional studies identified, 43 provided sufficient data to assess associations. High maternal weight, primiparity, and early weight gain, were related to an increased risk of early breast onset/development in most of the studies that analysed these associations, whereas late breast onset/development was associated with preterm birth. Results were inconsistent for smoking in pregnancy, maternal hypertensive disorders, breastfeeding, diabetes, and small for gestational age. No association emerged for maternal age at delivery, alcohol drinking, and selected drug use during pregnancy, and low birth weight.

CONCLUSIONS

The results of this review show that high maternal weight, primiparity and early weight gain were associated with an increased risk of early breast onset/development. Late breast onset/development was associated with preterm birth. Breast development is a key physical marker of puberty onset, and early puberty development is linked to consequences that can reverberate throughout life. Answering the questions about the interconnections between pre/postnatal environmental exposures and their impact on puberty, represents an important area of multidisciplinary research.

Diet and Nutrients Intakes during Infancy and Childhood in Relation to Early Puberty: A Systematic Review and Meta-Analysis

The onset of puberty has become earlier over the decades, and nutrients and diet are related to the timing of puberty onset. Hence, we aimed to investigate the association between diet or nutrients in infancy, childhood and early puberty. PubMed, Embase, and Cochrane library were searched systematically up to 15 April 2022. The pooled relative risks (RRs) or regression coefficients (beta) were estimated using the random-effect model or fixed-effect model according to the heterogeneity between studies. Twenty-two articles on diet or nutrients in childhood and six about breastfeeding in infancy were included. The prolonged breastfeeding duration in infancy could reduce the risk of early menarche (beta 0.31, 95% CI: 0.01, 0.60, p = 0.045). The high intake of yogurt was associated with a 35% reduction in the risk of earlier menarche (RR 0.65, 95% CI: 0.47, 0.89, p = 0.008). Girls with severe food insecurity experienced later menarche (RR 0.81, 95% CI: 0.67, 0.98, p = 0.027). Conversely, due to the high intake of protein, the risk of early menarche increased by 8% (RR 1.08, 95% CI: 1.01, 1.16, p = 0.016). High intake of yogurt, longer duration of breastfeeding, and food insecurity decreased the possibility of earlier menarche, while high intake of protein increased that risk. As a modifiable factor, diet and nutrients in infancy and childhood provide new insights into the future prevention of early puberty.

Associations of maternal urinary bisphenol and phthalate concentrations with offspring reproductive development

Fetal exposure to bisphenols and phthalates may influence development of the reproductive system. In a population-based, prospective cohort study of 1059 mother-child pairs, we examined the associations of maternal gestational urinary bisphenols and phthalates concentrations with offspring reproductive development from infancy until 13 years. We measured urinary bisphenol and phthalate concentrations in each trimester. We obtained information on cryptorchidism or hypospadias after birth from medical records. At 9.7 years, we measured testicular and ovarian volume by MRI. At 13.5 years, we measured child Tanner stages and menstruation through questionnaire. We performed linear or logistic regression models for boys and girls to assess the associations of maternal urinary average and trimester-specific bisphenols and phthalates with child reproductive outcomes. Next, to further explore potential synergistic or additive effects of exposures together, we performed mixed exposure models using a quantile g computation approach. Models were adjusted for maternal age, ethnicity, body-mass index, education, parity, energy intake, smoking and alcohol use, and child's gestational age at birth, birthweight and body-mass index. In boys, no associations of maternal gestational phthalate or bisphenol with offspring cryptorchidism and hypospadias were found. Higher maternal high-molecular-weight phthalate and total bisphenol, but not phthalic acid or low-molecular-weight phthalate, were associated with larger child testicular volume at 10 years. Higher maternal phthalic acid and total bisphenol were associated with earlier genital and pubic hair development at 13 years, respectively (p-values<0.05). In girls, we found no associations of maternal urinary bisphenol and phthalate with ovarian volume or menstrual age. Only higher maternal urinary high-molecular-weight phthalate was associated with earlier pubic hair development at 13 years (p-values <0.05). Higher mixture exposure was associated with earlier pubic hair development in both sexes. In conclusion, higher maternal gestational urinary bisphenol and phthalate concentrations were associated with alterations in offspring reproductive development, mainly in boys.

Associations between infant growth and pubertal onset timing in a multiethnic prospective cohort of girls

Background

Early puberty increases risk of adverse health conditions throughout the life course. US girls are experiencing earlier puberty without clear reasons. Studies suggest early life factors, such as infant growth, may influence pubertal timing. We assessed the associations between infant growth and onset of breast development (thelarche), pubic hair development (pubarche), and menarche in girls.

Methods

A prospective cohort of girls born at a Kaiser Permanente Northern California medical facility in 2005–11 was used. Weight-for-age z-scores were calculated at birth and 24 months. Difference in z-scores greater than 0.67 represent rapid “catch-up” growth, less than -0.67 represent delayed “catch-down” growth, and between -0.67 and 0.67 represent “normal” growth. Pubertal onset was measured using clinician-assessed sexual maturity ratings (SMRs) and defined as the age at transition from SMR 1 to SMR 2 + for both thelarche and pubarche. SMR data was collected through June 2020. Menarche was analyzed as a secondary outcome. Weibull and modified Poisson regression models were used. Models were adjusted for potential confounders.

Results

There were 15,196 girls included in the study. Approximately 30.2% experienced catch-up growth, 25.8% experienced catch-down growth, and 44% had normal growth. Girls with catch-up growth had increased risk of earlier thelarche (hazard ratio = 1.26, 95% confidence interval (CI): 1.18, 1.35), pubarche (1.38, 95% CI: 1.28, 1.48), and menarche (< 12y, relative risk = 1.52, 95% CI: 1.36, 1.69) compared to those with normal growth, after adjusting for covariates. These associations were partially mediated by childhood body mass index. Catch-down growth was associated with later pubertal onset.

Conclusions

Girls who experience infant catch-up growth have higher risk of earlier pubertal development compared to girls with normal growth and the associations are partially explained by childhood obesity. This information may help clinicians to monitor girls who are at high risk of developing earlier.

Analysis of Early-Life Growth and Age at Pubertal Onset in US Children

Importance

Earlier pubertal onset may be associated with an increased risk of chronic diseases. However, the extent to which growth in the first 5 years of life-an important developmental life stage that lays the foundation for later health outcomes-is associated with pubertal onset remains understudied.

Objective

To assess whether changes in weight, length or height, and body mass index (BMI, calculated as weight in kilograms divided by height in meters squared) during the first 5 years of life are associated with earlier pubertal onset.

Design, Setting, and Participants

This cohort study used data from 36 cohorts participating in the Environmental Influences on Child Health Outcomes program from January 1, 1986, to December 31, 2015. Participant inclusion required at least 1 anthropometric measure in the first 5 years of life and at least 1 measure of pubertal onset. Data were analyzed from January 1 to June 30, 2021.

Exposures

Standardized velocities of weight, length or height, and BMI gain in early infancy (0-0.5 years), late infancy (0.5-2 years), and early childhood (2-5 years).

Main Outcomes and Measures

Markers of pubertal onset for boys and girls, including age at peak height velocity (APHV), time to puberty score greater than 1, time to Tanner pubic hair stage greater than 1, and time to menarche. Multivariable regression models were used to estimate mean differences in APHV by growth periods.

Results

Of 7495 children included in the study, 3772 (50.3%) were girls, 4505 (60.1%) were White individuals, and 6307 (84.1%) were born during or after the year 2000. Girls had a younger APHV (10.8 vs 12.9 years) than boys. In boys, faster weight gain (per 1-SD increase) in early infancy (β, -0.08 years; 95% CI, -0.10 to -0.06), late infancy (β, -0.10 years; 95% CI, -0.12 to -0.08), and early childhood (β, -0.07 years; 95% CI, -0.08 to -0.05) was associated with younger APHV after adjusting for the child's birth year, race, and Hispanic ethnicity as well as maternal age at delivery; educational level during pregnancy; annual household income during pregnancy; prenatal cigarette smoking; whether the mother was nulliparous; whether the mother had gestational diabetes, hypertension, or preeclampsia; mode of delivery; prepregnancy BMI; gestational weight gain; and gestational age at delivery. Similar associations were observed for length or height and BMI gains during the same age periods. In girls, faster gains (per 1-SD increase) in weight (β, -0.03 years; 95% CI, -0.05 to -0.01) and height (β, -0.02 years; 95% CI, -0.04 to 0.00) in early childhood were associated with younger APHV. Faster BMI gain in late infancy was associated with earlier time to menarche, whereas faster BMI gain in early childhood was associated with earlier time to Tanner pubic hair stage greater than 1.

Conclusions and Relevance

This cohort study found that faster gains in weight, length or height, or BMI in early life were associated with earlier pubertal onset. The results suggest that children who experience faster early growth should be monitored closely for earlier onset of puberty and referred as appropriate for supportive services.

Nutrition in adolescent growth and development

During adolescence, growth and development are transformative and have profound consequences on an individual's health in later life, as well as the health of any potential children. The current generation of adolescents is growing up at a time of unprecedented change in food environments, whereby nutritional problems of micronutrient deficiency and food insecurity persist, and overweight and obesity are burgeoning. In a context of pervasive policy neglect, research on nutrition during adolescence specifically has been underinvested, compared with such research in other age groups, which has inhibited the development of adolescent-responsive nutritional policies. One consequence has been the absence of an integrated perspective on adolescent growth and development, and the role that nutrition plays. Through late childhood and early adolescence, nutrition has a formative role in the timing and pattern of puberty, with consequences for adult height, muscle, and fat mass accrual, as well as risk of non-communicable diseases in later life. Nutritional effects in adolescent development extend beyond musculoskeletal growth, to cardiorespiratory fitness, neurodevelopment, and immunity. High rates of early adolescent pregnancy in many countries continue to jeopardise the growth and nutrition of female adolescents, with consequences that extend to the next generation. Adolescence is a nutrition-sensitive phase for growth, in which the benefits of good nutrition extend to many other physiological systems.

Gut microbiota and its derived SCFAs regulate the HPGA to reverse obesity-induced precocious puberty in female rats

The intestinal microbiota and its derived short-chain fatty acids (SCFAs) can reverse obesity and obesity-related metabolic diseases, but whether it has an effect on obesity complicated by precocious puberty and its potential mechanism need to be further understood. The purpose of this study was to investigate the effect of the gut microbiota and its derived short-chain fatty acids (SCFAs) on obesity-induced precocious puberty rats and their regulatory mechanisms. We constructed obesity-induced precocious puberty rats using a high-fat diet (HFD) had notable similarity to precocious puberty caused by obesity due to overeating in children. We then added acetate, propionate, butyrate or their mixture to the HFD, and investigated the effect of intestinal microbiota and its derived SCFAs on the hypothalamic-pituitary-gonadal axis (HPGA) in rats with obesity-induced precocious puberty. We found that obesity-induced precocious puberty rats had an early first estrous cycle, increased hypothalamic mRNA expression of Kiss1, GPR54 and GnRH, and early gonadal maturation. Meanwhile, the intestinal microbiota imbalance and the main SCFAs production decreased in the colon. The addition of acetate, propionate, butyrate or their mixture to the HFD could significantly reverse the precocious puberty of rats, reduce GnRH release from the hypothalamus and delay the development of the gonadal axis through the Kiss1-GPR54-PKC-ERK1/2 pathway. Our findings suggest that gut microbiota-derived SCFAs are promising therapeutic means for the prevention of obesity-induced precocious puberty and provide new therapeutic strategies with clinical value.

Association of mode of delivery with offspring pubertal development in Project Viva: a prospective pre-birth cohort study in the USA

STUDY QUESTION

Is cesarean delivery associated with earlier offspring pubertal development?

SUMMARY ANSWER

We identified that boys born by cesarean delivery developed puberty earlier, evidenced by an earlier age at peak height velocity and earlier attainment of puberty score > 1, than boys born by vaginal delivery.

WHAT IS KNOWN ALREADY

Cesarean delivery is posited to have long-term effects on health outcomes. However, few studies have examined whether mode of delivery is related to pubertal development.

STUDY DESIGN, SIZE, DURATION

Prospective pre-birth cohort study consisting of 1485 mother-child pairs enrolled during pregnancy from obstetric practices and followed up until early adolescence (median age 12.9 years). Participant inclusion required data on mode of delivery and at least one measure of pubertal development.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Participants are children from the Project Viva study. We abstracted information on delivery mode from electronic medical records from children followed since birth (1999-2002) and examined the following markers of pubertal development: age at peak height velocity (APHV); age at menarche (girls only); parent-reported pubertal development score; and child-reported pictograph Tanner pubic hair staging. We used multivariable regression models to examine associations of delivery mode with these four pubertal indices, adjusting for the following confounders: demographic and socioeconomic factors; maternal height, pre-pregnancy BMI, total gestational weight gain, pregnancy conditions, parity, and maternal age at menarche; paternal height and BMI; gestational age at delivery and birthweight-for-gestational-age z-score.

MAIN RESULTS AND THE ROLE OF CHANCE

In this study, 23.2% of children were born by cesarean delivery. Girls had an earlier APHV, had a higher pubertal score throughout childhood and in early adolescence, and were more likely to attain puberty score >1 and Tanner pubic hair Stage >1 earlier compared to boys. Mean (SD) age at menarche in girls was 12.4 (1.0) years. Boys born by cesarean delivery had significantly earlier APHV (β -0.23 years; 95% CI -0.40, -0.05) and higher risk of earlier attainment of puberty score > 1 (hazard ratio 1.09; 95% CI 1.01, 1.19) than boys born by vaginal delivery, after adjusting for confounders. These associations were not mediated by pre-pubertal BMI and were similar for planned (no labor) and unplanned (labor) cesarean delivery. No associations were observed between delivery mode and time to attain Tanner pubic hair Stage > 1 in boys. In girls, mode of delivery was not associated with any of the measured pubertal development markers.

LIMITATIONS, REASONS FOR CAUTION

This study used, as secondary outcomes, parent- and child-reported measures of pubertal development, which may be more prone to error and misclassification than information collected by trained observers or physicians during clinical examinations. The findings may also not be generalizable to populations from different settings, because all participants lived in one geographic area, were well educated, and had health care.

WIDER IMPLICATIONS OF THE FINDINGS

Our findings provide support for cesarean delivery as a potential indicator of identifying children who are likely to experience earlier pubertal development; however, more studies are needed to confirm or refute these observations.

STUDY FUNDING/COMPETING INTEREST(S)

The project was funded by grants from the National Institutes of Health. The authors have no financial relationships or competing interests to disclose.

TRIAL REGISTRATION NUMBER

N/A.

Early-life exposures and age at thelarche in the Sister Study cohort

BACKGROUND

Early age at breast development (thelarche) has been associated with increased breast cancer risk. Average age at thelarche has declined over time, but there are few established risk factors for early thelarche. We examined associations between pre- and postnatal exposures and age at thelarche in a US cohort of women born between 1928 and 1974.

METHODS

Breast cancer-free women ages 35-74 years who had a sister diagnosed with breast cancer were enrolled in the Sister Study from 2003 to 2009 (N = 50,884). At enrollment, participants reported information on early-life exposures and age at thelarche, which we categorized as early (≤ 10 years), average (11-13 years), and late (≥ 14 years). For each exposure, we estimated odds ratios (ORs) and 95% confidence intervals (CIs) for early and late thelarche using polytomous logistic regression, adjusted for birth cohort, race/ethnicity and family income level in childhood.

RESULTS

Early thelarche was associated with multiple prenatal exposures: gestational hypertensive disorder (OR = 1.25, 95% CI 1.09-1.43), diethylstilbestrol use (OR = 1.23, 95% CI 1.04-1.45), smoking during pregnancy (OR = 1.20, 95% CI 1.13-1.27), young maternal age (OR 1.30, 95% CI 1.16-1.47 for < 20 vs. 25-29 years), and being firstborn (OR = 1.25, 95% CI 1.17-1.33). Birthweight < 2500 g and soy formula use in infancy were positively associated with both early and late thelarche.

CONCLUSIONS

Associations between pre- and postnatal exposures and age at thelarche suggest that the early-life environment influences breast development and therefore may also affect breast cancer risk by altering the timing of pubertal breast development.

The Role of Pediatric Nutrition as a Modifiable Risk Factor for Precocious Puberty

Puberty is a critical phase of growth and development characterized by a complex process regulated by the neuroendocrine system. Precocious puberty (PP) is defined as the appearance of physical and hormonal signs of pubertal development at an earlier age than is considered normal. The timing of puberty has important public health, clinical, and social implications. In fact, it is crucial in psychological and physical development and can impact future health. Nutritional status is considered as one of the most important factors modulating pubertal development. This narrative review presents an overview on the role of nutritional factors as determinants of the timing of sexual maturation, focusing on early-life and childhood nutrition. As reported, breast milk seems to have an important protective role against early puberty onset, mainly due to its positive influence on infant growth rate and childhood overweight prevention. The energy imbalance, macro/micronutrient food content, and dietary patterns may modulate the premature activation of the hypothalamic-pituitary-gonadal axis, inducing precocious activation of puberty. An increase in knowledge on the mechanism whereby nutrients may influence puberty will be useful in providing adequate nutritional recommendations to prevent PP and related complications.

Obesity is a risk factor for central precocious puberty: a case-control study

BACKGROUND

Obesity is an important underlying cause of central precocious puberty (CPP), but previous large studies are flawed by using just age and breast examination to diagnose CPP. We aimed to determine whether overweight and obesity in childhood increases hormonally diagnosed CPP.

METHODS

Our retrospective, case-control study recruited 846 children diagnosed as having CPP and randomly sampled 1650 healthy control subjects in Xingtai Third Hospital in China between November 2018 and March 2021. Information was obtained from an electronic medical record and questionnaire investigated in the outpatient visit. Observations were made before the a priori hypothesis. Unconditional logistic regression for analysis was used to determine whether overweight and obesity status and duration of overweight/obesity were associated with CPP.

RESULTS

Overweight and obesity were significantly associated with increased odds of CPP among girls, even after adjusting for birth weight, exclusive breastfeeding for 6 month, household income, maternal overweight, paternal overweight, and maternal menarche age (overweight: the adjusted odds ratio (aOR) (95%CI): 1.92 (1.16, 3.24), p = 0.02; obesity: aOR (95%CI): 1.78 (1.13, 3.48), p = 0.03). Furthermore, the effects of overweight and obesity were significant when ongoing for 1 to 2 years, 2 to 3 years, and greater than 3 years, but not at less than 1 year. For boys, association between obesity and increased odds of CPP was observed (aOR (95%CI): 1.68 (1.09, 3.75), p = 0.03). The effects of overweight and/or obesity were only significant when ongoing for greater than 2 years.

CONCLUSIONS

Prolonged overweight and obesity in early childhood may be risk factors for CPP, especially in girls. Weight loss might be an important approach for the prevention of precocious puberty in children.

Breast feeding and timing of puberty in boys and girls: A nationwide cohort study

BACKGROUND

Breast feeding has been associated with improved infant health, but its impact on pubertal timing remains uncertain, particularly in boys.

OBJECTIVE

The objective of this study was to investigate the association between duration of breast feeding and pubertal timing in boys and girls.

METHODS

This population-based cohort study included 13 511 boys and girls from the Puberty Cohort nested within the Danish National Birth Cohort. The children gave half-yearly, self-reported information on pubertal development through questionnaires (Tanner stages, age at menarche, first ejaculation, voice break, axillary hair growth, and acne). Information on breast feeding was provided by the mothers when the children were 6 months of age. We estimated mean differences (in months) in age at attaining each pubertal marker and for overall timing of puberty (combined estimate) for every additional month of exclusive breast feeding. Furthermore, we estimated differences in pubertal age when comparing children never exclusively breastfed and exclusively breastfed <4 months using children exclusively breastfed ≥4 months as reference. In sub-analyses, we further adjusted for infant weight gain and childhood BMI at 7 years to investigate whether these variables mediated the association.

RESULTS

Boys tended to reach pubertal markers later for every additional month of exclusive breast feeding (combined estimate: 0.2 (95% confidence interval [CI] 0.0, 0.4 months). Never exclusively breastfed boys reached pubertal markers earlier than the boys exclusively breastfed ≥4 months (combined estimate: -4.1 (95% CI -6.7, -1.6) months). Boys exclusively breastfed <4 months also reached pubertal markers earlier than those never exclusively breastfed but with smaller differences. In girls, duration of breast feeding was not associated with pubertal development. When including infant weight gain or childhood BMI, the results remained essentially unchanged.

CONCLUSIONS

Shorter duration of exclusive breast feeding was associated with earlier pubertal development in boys but not in girls.

Breastmilk Feeding during the First 4 to 6 Months of Age and Childhood Disease Burden until 10 Years of Age

BACKGROUND

Breastfeeding is recommended due to its beneficial effects on human health. However, the effect of breastfeeding on health differs, resulting in various childhood diseases.

OBJECTIVE

Our purpose was to investigate the association between breastfeeding at least in the first 4 months and the subsequent development of 15 certainly defined childhood diseases until 10 years of age, the all-cause hospitalization rate and growth at 6-7 years of age.

METHODS

Participants included propensity-score matched 188,052 children born between January 2008 and December 2009, who were followed up till 10 years of age. Data were taken from the National Investigation of birth Cohort in Korea study 2008 database. Risk ratios were obtained using a modified Poisson regression and weighted risk differences using binomial regression.

RESULTS

Compared to formula feeding, breastfeeding was associated with decreased risks of febrile convulsion, attention deficit hyperactivity disorder and autism spectrum disorder, pneumonia, acute bronchiolitis, hypertrophic pyloric stenosis, asthma, all-cause hospitalization, overweight/obesity and short stature. Exclusive breastfeeding at 4 to 6 months of age had similar results to exclusive breastfeeding over 6 months of age.

CONCLUSIONS

Breastfeeding in early infancy reduces the risk for various childhood diseases, all-cause hospitalization rate, obesity, and short stature during childhood.

The link between obesity and puberty: what is new?

PURPOSE OF REVIEW

The objective of this review is to assess the most recent literature on pubertal trends in boys and girls as well as evaluate genetic, epigenetic, and environmental factors implicated in the timing of pubertal progression.

RECENT FINDINGS

Recent studies confirm the previously described link between increased adiposity and earlier onset of puberty in girls, and more recent studies shed light onto the previously unclear situation in boys as a preponderance of recent longitudinal studies suggests that increased adiposity is linked with earlier pubertal timing also in boys. Discoveries of novel pathways highlights the complexity of pubertal development and suggest mechanistic links between nutrition, obesity, leptin, insulin resistance, and puberty. Furthermore, genetic and epigenetic variants can be linked to early puberty. Other factors, such as prenatal and postnatal environment, gut microbiota, and endocrine-disrupting chemicals have also been linked to both obesity and earlier puberty.

SUMMARY

Understanding how the interactions of these factors contribute the relationship between obesity and early pubertal onset is crucial as early puberty has been linked with long-term consequences, such as short stature, earlier type 2 diabetes, cardiovascular disease, and poor psychological and behavioral outcomes.

Association of Soy and Exclusive Breastfeeding With Central Precocious Puberty: A Case-Control Study

Introduction

While soy is suggested as a possible risk factor, exclusive breastfeeding (EBF) has a likely protective effect in precocious puberty. Our aim was to evaluate the association between both of these variables with central precocious puberty (CPP).

Methods

We performed a retrospective, case-control study. A total of 161 girls were divided into two groups: 84 patients diagnosed with CPP composed the case group and 77 patients without the diagnosis of CPP (had gone through normal onset of puberty) were the control group.

Results

Our control group had a higher presence of EBF >6 months, which was an important protective factor for CPP (OR: 0.5; IC 95%: 0.3-0.9, p = 0.05) and also correlated negatively with the presence of it (r = -0.2; p < 0.05). Oppositely, the use of soy was significantly higher in the CPP group, (OR: 3.8; IC 95%: 1.5-6, p < 0.05) and positively correlating (r = 0.2; p < 0.01) with the presence of CPP. Duration of soy intake (years) correlated with bone age (r = 0.415; p < 0.05). A logistic regression was performed to evaluate the effects of EBF duration and soy on CPP. The model was significant (x² (2) = 20,715, p = <0.001) and explained 12.2% (Nagelkerke R2) of the variance, correctly classifying 62.5% of cases. EBF was associated with a reduction of likelihood of having CPP [OR = 0,187 (CI = 0.055-0,635); Wald = 7,222, p = 0.007], while soy intake increased the risk [OR = 3.505 (CI) = 1,688-7,279, Wald = 11,319, p = 0.001].

Conclusion

Our data found the use of soy was associated with CPP. Additionally, EBF was pointed as a protective factor. However, future prospective studies are needed to clarify this issue.

The Role of Fetal, Infant, and Childhood Nutrition in the Timing of Sexual Maturation

Puberty is a crucial developmental stage in the life span, necessary to achieve reproductive and somatic maturity. Timing of puberty is modulated by and responds to central neurotransmitters, hormones, and environmental factors leading to hypothalamic-pituitary-gonadal axis maturation. The connection between hormones and nutrition during critical periods of growth, like fetal life or infancy, is fundamental for metabolic adaptation response and pubertal development control and prediction. Since birth weight is an important indicator of growth estimation during fetal life, restricted prenatal growth, such as intrauterine growth restriction (IUGR) and small for gestational age (SGA), may impact endocrine system, affecting pubertal development. Successively, lactation along with early life optimal nutrition during infancy and childhood may be important in order to set up timing of sexual maturation and provide successful reproduction at a later time. Sexual maturation and healthy growth are also influenced by nutrition requirements and diet composition. Early nutritional surveillance and monitoring of pubertal development is recommended in all children, particularly in those at risk, such as the ones born SGA and/or IUGR, as well as in the case of sudden weight gain during infancy. Adequate macro and micronutrient intake is essential for healthy growth and sexual maturity.

Prenatal anxiety, breastfeeding and child growth and puberty: linking evolutionary models with human cohort studies

Background: Stress experienced by mothers during pregnancy can have both immediate and long-term effects on child development, potentially mediated by breastfeeding.Aim: Using a UK birth cohort study, we asked how maternal stress relates to breastfeeding and consequences for growth and puberty onset.Subjects and methods: We analysed data from the Avon Longitudinal Study of Parents and Children, collected via questionnaires and clinic visits (N: 698-8,506). We used reports of prenatal anxiety, breastfeeding, early growth and age at menarche or first voice change. Confounding by maternal age, parity, smoking, education and body mass index (BMI) was considered.Results: Mothers with higher levels of reported anxiety were less likely to breastfeed (Odds ratio (OR): 0.83, 95% confidence interval (CI): 0.71, 0.97). Breastfed infants had slower growth before weaning, although growth differences were unclear thereafter. Being breastfed for more than six months was associated with later puberty onset in females (2.76 months later than non-breastfed; CI: 0.9, 4.63), although the association was attenuated by confounders and BMI (1.51 months, CI: -0.38, 3.40). No association between breastfeeding and puberty onset in males was found.Conclusion: Our studies fit results shown previously, and we consider these in light of evolutionary life history theory while discussing key challenges in such an approach.