Having siblings promotes a more healthy weight status—Whereas only children are at greater risk for higher BMI in later childhood

Effect of maternal previous pregnancy on children's pubertal development: an 8-year pubertal cohort

STUDY QUESTION

Does the maternal pregnancy history affect the course of their offspring's pubertal development?

SUMMARY ANSWER

Maternal pregnancy history, particularly adverse outcomes, significantly influences the timing of menarche and the tempo of breast development in girls.

WHAT IS KNOWN ALREADY

Preliminary evidence indicates that parity may affect the onset of puberty, mainly as reflected by changes in the timing of pubic and axillary hair development.

STUDY DESIGN, SIZE, DURATION

This 8-year cohort, conducted semi-annually, was recruited from four primary schools. The average follow-up duration was 6.09 years (range: 2-8 years).

PARTICIPANTS/MATERIALS, SETTING, METHODS

The study cohort comprised 1390 children, including 710 girls and 680 boys, with age ranges of 6.58-19.26 years and 5.81-19.28 years, respectively, over an 8-year follow-up period. The primary exposure was whether the mother has a history of pregnancy prior to the birth of the child, including childbearing, miscarriage, and other adverse pregnancy outcomes. Pubertal milestones as assessed by a professional, including breast and genital development, were modeled using logistic regression, and the age of menarche was documented for girls. Associations between maternal pregnancy history and pubertal progression in both genders were analyzed using generalized linear regression models.

MAIN RESULTS AND THE ROLE OF CHANCE

Girls from non-first pregnancies experienced a delayed age at menarche by 0.22 years (95% CI: 0.05, 0.38) and a more rapid tempo of breast development (0.06; 95% CI: 0.01, 0.11) compared to those from first pregnancies, particularly among girls with a history of maternal adverse pregnancy outcomes. The effect of maternal pregnancy history on pubertal development was less pronounced in boys than in girls.

LIMITATIONS, REASONS FOR CAUTION

The sample was relatively small, and the cohort also lacks sufficient data due to missing data points and some study participants still maturing. While model fitting aids in describing incomplete pubertal development, the logistic growth mixed-effects model's assumptions about growth curves may not fully reflect reality.

WIDER IMPLICATIONS OF THE FINDINGS

Maternal pregnancy history, particularly adverse outcomes, can markedly influence pubertal progression in girls. Previous studies have shown that the timing and tempo of pubertal development impact adolescent psychological and behavioral health, and have implications for reproductive health and diseases in adulthood. Optimal pregnancy planning by mothers is essential for enhancing the well-being of both mother and offspring.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by Chongqing Natural Science Foundation project (CSTB2023NSCQ-MSX0133), National Natural Science Foundation of China (81973067), National Youth Science Fund Project (81502825), and Program for Youth Innovation in Future Medicine, Chongqing Medical University (W0054). This study was conducted according to the guidelines of the Declaration of Helsinki, and approved by the Ethics Committee of Chongqing Medical University (Reference Number: 2023003). Informed consent was obtained from all participants and their guardians involved in the study. The authors declared that they have no conflicts of interest to disclose.

TRIAL REGISTRATION NUMBER

N/A.

Consecutive Lactation, Infant Birth Weight and Sex Do Not Associate with Milk Production and Infant Milk Intake in Breastfeeding Women

BACKGROUND/OBJECTIVES

Optimal infant growth is reliant on the sufficient intake of human milk. Studies in animal models speculate that multiparous mothers produce a higher milk yield compared to primiparous mothers. We aimed to examine if there are relationships between consecutive lactations and infant demographics and both maternal 24 h milk production (MP) and infant milk intake (MI).

METHODS

Lactating mothers 1-6 months postpartum (n = 36; 25 fully breastfeeding (FBF), 11 supplementing with commercial milk formula (partly breastfeeding (PBF)) test-weighed their infants for 24 h during two consecutive lactations and provided demographic information. Twenty-four-hour MP by breast, infant MI (including mothers' own expressed milk and formula), breastfeeding and expressing frequencies were measured. The statistical analysis used linear mixed modelling accounting for infant birth weight (FBF) or time postpartum (PBF) and for the random effect of the participant.

RESULTS

In the FBF group, there were no differences between lactations in terms of MP (p = 0.31) or the infant mother's own MI (p = 0.14). The birth weight was higher for consecutive lactation infants (p = 0.008). Infant sex was not associated with MP (p = 0.12) or the infant mother's own MI (p = 0.090). In the PBF group, the breastfeeding frequency (p = 0.042), MP (p = 0.025) and infant mother's own MI (p = 0.019) were higher in consecutive lactations whilst formula intake was lower (p = 0.004).

CONCLUSIONS

This study suggests that in fully breastfeeding women, there is no significant effect of consecutive lactation or infant sex on MP or infant MI during established lactation.

Data Resource Profile: ECHILD only-children and siblings (ECHILD-oCSib): a national cohort of linked health, education and social care data on mothers and children in England

Introduction

Sibling dynamics play a crucial role in individual development, health and wellbeing. We established a national birth cohort using administrative health, education and social care data in England featuring clusters of mothers and their children (mothers and only-children, MoC; and mothers and siblings, MSib).

Methods

From 13.6 million mother-baby pairs from births between April 1997 and January 2022 captured in Hospital Episode Statistics in England, we identified MoC and MSib clusters by identifying livebirths linked to the same mother. We compared only-children and children with siblings, by ethnicity, sociodemographic variables, and birth characteristics. We calculated birth intervals for children with siblings.

Results

We identified 4,086,648 MoC and 3,957,856 MSib clusters. Compared with only-children, children with siblings were more likely to be Asian, live in more deprived areas, and have younger mothers, but were less likely to be overdue births (>=42 weeks), or to have very low birth weight (<1500g). Children with siblings were also less likely to have been admitted to special neonatal care after birth compared to only-children. Among the MSib clusters, sibship sizes varied between 2 and 15, with a mean of 2.4 children per mother. The median birth interval was 3.0 years.

Conclusion

This national cohort ECHILD-oCSib of 4.1 million MoC and 4.0 million MSib clusters in England is an important resource for investigating the effects of maternal exposures, sibling dynamics and their interplay on individual development, health and wellbeing. Potential sources of bias should be considered in analyses of these data.

Key features

We derived a national cohort of 4.1 million clusters of mothers and only-children and 4.0 million clusters of mothers and siblings using administrative health, education and social care data in England.Compared with only-children, children with siblings were more likely to be Asian, live in more deprived areas, and have younger mothers, but less likely to be overdue births (>=42 weeks of gestation), or to have very low birth weight (<1500 g).Among children with siblings, sibship sizes varied between 2 and 15, with a mean of 2.4 children per mother (median = 2.0). The median birth interval was 3.0 years.The cohort is linked to longitudinal administrative data on health, education and social care use, and provides a valuable opportunity to investigate the effects of maternal factors, sibling dynamics, and their interaction on children development, health, education and wellbeing.The data can be accessed as part of ECHILD database.

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

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