Differences in Body Mass Index between Siblings Who Are Discordant for Exposure to Antenatal Maternal Smoking

Long-term adverse influence of smoking during pregnancy on height and body size of offspring at ten years old in the UK Biobank cohort

Background

To explore the long-term relationship between maternal smoking during pregnancy and early childhood growth in the UK Biobank cohort.

Methods

To estimate the effect of maternal smoking during pregnancy on offspring height and body size at ten years old, we performed binary logistic analyses and reported odds ratios (OR) as well as 95% confidence intervals (95%CIs). We also implemented the cross-contextual comparison study to examine whether such influence could be repeatedly observed among three different ethnicities in the UK Biobank cohort (n = 22,140 for White, n = 7094 for South Asian, and n = 5000 for Black). In particular, we conducted the sibling cohort study in White sibling cohort (n = 9953 for height and n = 7239 for body size) to control for unmeasured familial confounders.

Results

We discovered that children whose mothers smoked during pregnancy had greater risk of being shorter or plumper at age ten in the full UK Biobank White cohort, with 15.3% (95% CIs: 13.0%∼17.7%) higher risk for height and 32.4% (95%CIs: 29.5%∼35.4%) larger risk for body size. Similar associations were identified in the South Asian and Black ethnicities. These associations were robust and remained significant in the White sibling cohort (12.6% [95%CIs: 5.0%∼20.3%] for height and 36.1% [95%CIs: 26.3%∼45.9%] for body size) after controlling for family factors.

Conclusion

This study robustly confirms that maternal smoking during pregnancy can promote height deficit and obesity for offspring at ten years old. Our findings strongly encourage mothers to quit smoking during pregnancy for improving growth and development of offspring.

Interpregnancy weight gain and childhood obesity: analysis of a UK population-based cohort

BACKGROUND

Maternal obesity increases the risk of adverse long-term health outcomes in mother and child including childhood obesity. We aimed to investigate the association between interpregnancy weight gain between first and second pregnancies and risk of overweight and obesity in the second child.

METHODS

We analysed the healthcare records of 4789 women in Hampshire, UK with their first two singleton live births within a population-based anonymised linked cohort of routine antenatal records (August 2004 and August 2014) with birth/early life data for their children. Measured maternal weight and reported height were recorded at the first antenatal appointment of each pregnancy. Measured child height and weight at 4-5 years were converted to age- and sex-adjusted body mass index (BMI z-score). Log-binomial regression was used to examine the association between maternal interpregnancy weight gain and risk of childhood overweight and obesity in the second child. This was analysed first in the whole sample and then stratified by baseline maternal BMI category.

RESULTS

The prevalence of overweight/obesity in the second child was 19.1% in women who remained weight stable, compared with 28.3% in women with ≥3 kg/m2 weight gain. Interpregnancy gain of ≥3 kg/m2 was associated with increased risk of childhood overweight/obesity (adjusted relative risk (95% CI) 1.17 (1.02-1.34)), with attenuation on adjusting for birthweight of the second child (1.08 (0.94-1.24)). In women within the normal weight range at first pregnancy, the risks of childhood obesity (≥95th centile) were increased with gains of 1-3 kg/m2 (1.74 (1.07-2.83)) and ≥3 kg/m2 (1.87 (1.18-3.01)).

CONCLUSION

Children of mothers within the normal weight range in their first pregnancy who started their second pregnancy with a considerably higher weight were more likely to have obesity at 4-5 years. Supporting return to pre-pregnancy weight and limiting weight gain between pregnancies may achieve better long-term maternal and offspring outcomes.

Antenatal Fetal Size and Obesity in Five-Year-Old Children in a Large Cohort Created by Data Linkage

Background: What is not well understood is the gestational age at which the fetal size deviates from normal for children who develop obesity. Here we test the hypothesis that large-for-gestational age before birth is associated with increased risk for obesity in early childhood. Methods: In this retrospective study, routinely acquired antenatal ultrasound assessments in the first, second, and third trimester were linked to anthropometric measurements at 5.5 years. Results: There were 15,760 individuals, including 678 with obesity, 1955 overweight, and 1254 thin. Compared with children of healthy weight, children who had obesity were shorter in the first trimester [mean difference 0.19 z scores (0.10, 0.28)] and heavier in the second [mean difference z scores 0.15 (0.03, 0.27)] and third trimester [mean difference z scores 0.18 (0.05, 0.32)]. Children in the thin category were lighter compared with children of healthy weight in the third trimester and those in the overweight category were heavier compared with children of healthy weight in the third trimester. All associations were independent of birth weight. Conclusions: The difference in growth trajectories between children who have obesity compared with overweight or thin suggests different underlying mechanisms.

Change in modifiable maternal characteristics and behaviours between consecutive pregnancies and offspring adiposity: A systematic review

Causal evidence links modifiable maternal exposures during the periconceptional period with offspring obesity. The interconception period may be an important time to intervene. We systematically identified studies examining change in modifiable maternal exposures between pregnancies and offspring adiposity. We searched for longitudinal studies published between 1990 and 2019, which included measurements taken on at least two occasions in the period from 1 year prior to the conception of the first birth to the time of the second birth, and which included a measure of adiposity in second, or higher order, siblings. Age, ethnicity and genetics were not considered modifiable; all other factors including length of the interpregnancy interval were. Eleven studies satisfied the inclusion criteria. Higher interpregnancy weight gain or loss, maternal smoking inception, mothers smoking in their first pregnancy and quitting, increasing the number of cigarettes smoked and longer interpregnancy intervals were positively associated with adiposity in second or higher order children. Vaginal birth after caesarean delivery was protective. Further research is needed to ascertain whether the risk of adiposity is fixed based on first pregnancy exposures or if interpregnancy change alters the risk for a subsequent child. This can inform the type and effectiveness of interventions for mothers prior to a subsequent pregnancy.

[In Utero Exposure to Maternal Smoking: Impact on the Child from Birth to Adulthood - CNGOF-SFT Expert Report and Guidelines for Smoking Management during Pregnancy]

INTRODUCTION

Smoking during pregnancy leads to fetal passive smoking. It is associated with several obstetrical complications and is a major modifiable factor of maternal and fetal morbidity. Long-term consequences also exist but are less well known to health professionals and in the general population.

METHODS

Consultation of the Medline® database.

RESULTS

Maternal smoking during pregnancy is associated in the offspring with sudden infant death syndrome (NP2), impaired lung function (NP2), lower respiratory infections and asthma (NP2), overweight and obesity (NP2), cancers (NP3), risk of tobacco use, nicotine dependence and early smoking initiation (NP2). Unadjusted analyses show associations between in utero tobacco exposure and cognitive deficits (NP3), impaired school performance (NP3) and behavioral disorders in children (NP2), which are in a large part explained by environmental factors. There is a cross-generational effect of smoking during pregnancy. For example, an increased risk of asthma is observed in the grandchildren of smoking women (NP4). The respective roles of ante- and post-natal smoking remain difficult to assess.

CONCLUSION

These results highlight the importance of prevention measures against tobacco use in the general population, as well as screening measures and support for smoking cessation before or at the beginning of the pregnancy.

Maternal weight change between successive pregnancies: an opportunity for lifecourse obesity prevention

Maternal obesity is a major risk factor for adverse health outcomes for both the mother and the child, including the serious public health problem of childhood obesity which is globally on the rise. Given the relatively intensive contact with health/care professionals following birth, the interpregnancy period provides a golden opportunity to focus on preconception and family health, and to introduce interventions that support mothers to achieve or maintain a healthy weight in preparation for their next pregnancy. In this review, we summarise the evidence on the association between interpregnancy weight gain with birth and obesity outcomes in the offspring. Gaining weight between pregnancies is associated with an increased risk of large-for-gestational age (LGA) birth, a predictor of childhood obesity, and weight loss between pregnancies in women with overweight or obesity seems protective against recurrent LGA. Interpregnancy weight loss seems to be negatively associated with birthweight. There is some suggestion that interpregnancy weight change may be associated with preterm birth, but the mechanisms are unclear and the direction depends if it is spontaneous or indicated. There is limited evidence on the direct positive link between maternal interpregnancy weight gain with gestational diabetes, pre-eclampsia, gestational hypertension and obesity or overweight in childhood, with no studies using adult offspring adiposity outcomes. Improving preconception health and optimising weight before pregnancy could contribute to tackling the rise in childhood obesity. Research testing the feasibility, acceptability and effectiveness of interventions to optimise maternal weight and health during this period is needed, particularly in high-risk and disadvantaged groups.

Effectiveness of a Multifactorial Intervention in the First 1000 Days of Life to Prevent Obesity and Overweight in Childhood: Study Protocol

(1) Background: Obesity is a global health problem, and its prevention must be a priority goal of public health, especially considering the seriousness of the problem among children. It is known that fetal and early postnatal environments may favor the appearance of obesity in later life. In recent years, the impact of the programs to prevent obesity in childhood has been scarce. The aim of this research is to evaluate the effectiveness of an intervention based on the concept of early programming. (2) Methods: Non-randomized controlled trial design. Inclusion criteria are: two-year-old infants whose gestational period begins in the 14 months following the start of the intervention, and whose mothers have made the complete follow-up of their pregnancy in the same clinical unit of the study. The intervention will be developed over all the known factors that affect early programming, during pregnancy up to 2 years of life. Data will be collected through a data collection sheet by the paediatricians. A unibivariate and multivariate analysis of the data will be carried out. (3) Ethics and dissemination: The trial does not involve any risk to participants and their offspring. Signed informed consent is obtained from all participants. Ethical approval has been obtained. (4) Results: It is expected that this study will provide evidence on the importance of the prevention of obesity from the critical period of the first 1000 days of life, being able to establish this as a standard intervention in primary care.

Survey of Neonates in Pomerania (SNiP): Study design and cohort update

BACKGROUND

The health status of newborns is a major concern for parents and medical personnel. Recent studies have provided increasing evidence that factors from the foetal and perinatal periods of life influence health later in life. The "Follow-up of the Survey of Neonates in Pomerania" (SNiP-I-Follow-up) is the first follow-up of the population-based birth cohort study, SNiP-I, established in north-east Germany.

OBJECTIVES

The primary aim of SNiP-I-Follow-up study was the collection of longitudinal data on children and adolescents. The associations will be analysed between risk factors in pregnancy and the perinatal period and health status in infancy and later childhood.

POPULATION

The population-based cohort study SNiP-I was conducted in Pomerania in north-east Germany between February 2002 and November 2008. All mothers from the SNiP-I birth cohort were recontacted when their children were from 9 to 15 years of age.

DESIGN

The SNiP-I-Follow-up study was carried out between December 2016 and August 2017 and is a questionnaire-based survey.

METHODS

Physical development, health status, and social behaviour (school and leisure behaviour) of children were analysed using a questionnaire comprising medical, epidemiological, and socio-economic data, associated health care risk factors, and life circumstances of newborns, children, and their parents.

PRELIMINARY RESULTS

Out of 5725 children invited to participate in the SNiP-I-Follow-up study between December 2016 and August 2017, 29% (n = 1665) children participated in the SNiP-I-Follow-up study, providing data on 1665 mothers-child dyads. Responders had higher socio-economic status, especially in relation to maternal education status.

CONCLUSION

As a longitudinal birth cohort from rural Germany, the SNiP cohort will be a resource to address urgent research needs and contribute to overall population health.

Examining Associations between Perinatal and Postnatal Risk Factors for Childhood Obesity Using Sibling Comparisons

Background: One of the major criticisms of observational studies examining risk factors for childhood obesity is unmeasured confounding. We examined the associations between breastfeeding initiation, cesarean delivery, prenatal smoking, and gestational diabetes mellitus (GDM) with childhood obesity using both a traditional observational approach and a sibling-pair design with family fixed effects. Methods: We used data from the Linked the Collecting Electronic Nutrition Trajectory Data Using e-Records of Youth (CENTURY) Study, a clinical database created through the linkage of well-child visits with children's birth certificates, with obesity measured at 2 (N = 55,058) and 5 (N = 43,894) years of age. We conducted three sets of regression models: (1) full sample to examine the adjusted association between each risk factor and obesity with clustering by family; (2) rerun only among siblings with clustering by family; and (3) fixed effects analysis among siblings. Results: Across risk factors, 30%-39% of children had siblings. In the full sample, breastfeeding initiation was associated with a lower BMI z-score, while cesarean delivery and smoking during pregnancy were associated with a higher BMI z-score. Effect sizes were consistent in models with siblings only. However, in the fixed effects models, the coefficients attenuated and were no longer significant for each of these risk factors. We found no association between GDM and child BMI z-score in any of the models. Results were consistent for childhood obesity as a dichotomous measure and at 5 years of age. Conclusions: Our findings suggest that unmeasured genetic, environmental, and familial factors are likely confounding associations between breastfeeding, cesarean delivery, prenatal smoking, and GDM with childhood obesity in observational studies.

Maternal smoking early in pregnancy is associated with increased risk of short stature and obesity in adult daughters

We assessed anthropometry in 22,421 adult daughters in association with their mothers’ tobacco smoking early in pregnancy (at their first antenatal visit) in Sweden, particularly their risk of short stature and obesity. Adult daughters were grouped by maternal smoking levels during pregnancy: Non-smokers (58.5%), Light smokers (24.1%; smoked 1–9 cigarettes/day), and Heavier smokers (17.4%; smoked ≥10 cigarettes/day). Anthropometry was recorded on the adult daughters at approximately 26.0 years of age. Obesity was defined as BMI ≥30 kg/m², and short stature as height more than two standard deviations below the population mean. Daughters whose mothers were Light and Heavier smokers in early pregnancy were 0.8 cm and 1.0 cm shorter, 2.3 kg and 2.6 kg heavier, and had BMI 0.84 kg/m² and 1.15 kg/m² greater, respectively, than daughters of Non-smokers. The adjusted relative risk of short stature was 55% higher in women born to smokers, irrespectively of smoking levels. Maternal smoking had a dose-dependent association with obesity risk, with offspring of Heavier smokers 61% and of Light smokers 37% more likely to be obese than the daughters of Non-smokers. In conclusion, maternal smoking in pregnancy was associated with an increased risk of short stature and obesity in their adult daughters.