Birth Weight and Cardiorespiratory Fitness Among Young Men Born at Term: The Role of Genetic and Environmental Factors

Influence of Preterm Birth and Low Birthweight on Physical Fitness: A Systematic Review, Meta-Analysis, and Meta-Regression

BACKGROUND

Preterm birth and low birthweight (LBW) might be associated with reduced physical fitness, although evidence remains inconclusive.

OBJECTIVE

To examine the influence of preterm birth and LBW on physical fitness, as well as to assess whether variables such as gestational age, birthweight, or age at assessment moderate these effects.

METHODS

PubMed, Scopus, and PsycINFO were systematically searched from inception to 7 December 2023 for case-control and cohort studies analyzing the association between preterm birth or LBW (or gestational age or birthweight as continuous variables) with at least one physical fitness-related outcome (i.e., cardiorespiratory fitness (CRF), muscle strength, flexibility, speed, agility). Random-effects meta-analysis and meta-regression models were used to estimate the pooled effect size, as well as to examine potential associations between the magnitude of the effect and gestational age, birthweight, or age at assessment.

RESULTS

Fifty-two studies (n = 920,603 participants, average age ranging from 4.7 to 34.4 years) were included. Preterm birth was associated with reduced CRF (standardized mean difference (SMD) = -0.38, 95% confidence interval (CI) = -0.51 to -0.25) and muscle strength (SMD = -0.44, 95% CI = -0.79 to -0.08). LBW was associated with reduced CRF (SMD = -0.40, 95% CI = -0.64 to -0.17), muscle strength (SMD = -0.18, 95% CI = -0.24 to -0.13), flexibility (SMD = -0.11, 95% CI = -0.22 to -0.01), and agility (SMD = -0.99, 95% CI = -1.91 to -0.07). Meta-regression analyses showed that a lower gestational age or birthweight were associated with larger reductions in physical fitness, whereas no consistent association was found for the age at assessment.

CONCLUSION

Both preterm birth and LBW seem associated with reduced physical fitness regardless of age, with larger reductions overall observed in individuals with lower gestational age or birthweight. These findings might support the implementation of preventive strategies (e.g., fitness monitoring and physical exercise interventions) in these populations through the life course. PROSPERO registration: CRD42021231845.

The association between maternal healthy lifestyle factors during pregnancy and the neonatal anthropometric indicators based on a prospective cohort study

BACKGROUND AND OBJECTIVES

We aimed to evaluate the associations between a combined healthy lifestyle during the second and third trimesters and offspring anthropometric outcomes in China.

METHODS AND STUDY DESIGN

We examined these associations among 548 participants from nine community health centers and three hospitals in the North China cohort. A pregnant women's healthy lifestyle score (HLS) was constructed based on six lifestyle factors: smoking, alcohol consumption, physical activity, sedentary behavior, diet, and gestational weight gain. Anthropometric indicators at birth like birth weight (BW), head circumference (HC), and birth length (BL) were collected, and weight to head circumference ratio (WHC, kg/m), body mass index (BMI, kg/m2) and Ponderal Index (PI, kg/m3) were calculated. Multivariate linear and logistic regression models were used to examine the effects of HLS during the second and third trimesters on anthropometric outcomes at birth, respectively.

RESULTS

In fully adjusted models, we found a negative association between second and third-trimester HLS and offspring HC and a positive relationship between second-trimester HLS and BL (p<0.05). Neonates with mothers in the highest HLS tertile had a 5.6% relatively lower HC and 2.3% relatively longer body length than women in the lowest tertile. Each additional unit in third-trimester HLS had an associated decrease in HC by 0.96 cm. None of the associations between HLS and BW, WHC, BMI, and PI of offspring were observed.

CONCLUSIONS

A healthy lifestyle score may significantly impact offspring head circumference and body length, supporting the important role of healthy lifestyles in improving the health of offspring.

Influence of preterm birth on physical fitness in early childhood

Evidence suggests that preterm birth is associated with an impaired physical fitness later in life, but whether these effects are already visible since early childhood remains unknown. We aimed to compare the physical fitness of preterm preschoolers with that of children born at term. Children aged three to six years and born preterm (<35 weeks) were recruited from a Neonatal Intensive Care Unit, and children born at term (>37 weeks) were included as controls. A variety of physical fitness indicators (strength, cardiorespiratory fitness, agility, flexibility and balance) were assessed with the PREFIT battery and the adapted sit and reach test. Physical activity levels were measured through the PrePAQ questionnaire. A total of 98 preterm children (gestational age 32.4 ± 2.3 weeks, age 5.1 ± 0.8 years) and 74 controls (gestational age 39.9 ± 1.0 weeks, age 4.8 ± 0.9 years) were analysed. Despite no significant differences in physical activity levels (p > 0.05), preterm children showed an overall poorer physical fitness compared to controls. Specifically, preterm children had an impaired handgrip strength (-13.95%, p < 0.001), lower-limb muscle strength (-12.67%, p = 0.003), agility (-14.9%, p = 0.001), cardiorespiratory fitness (-12.73% p = 0.005) and flexibility (-17.04%, p = 0.001) compared to controls. An inverse dose-response association was observed between the level of prematurity and physical fitness, with very preterm children (gestational age ≤32 weeks) presenting the poorest fitness levels. In summary, prematurity seems to impair physical fitness since early childhood, which might support the need for promoting preventive strategies (e.g. fitness monitoring and applying exercise interventions).Highlights Preterm children present an impaired physical fitness compared with peers born at term since early childhood (3-6 years), as reflected by lower muscle strength, agility, flexibility and cardiorespiratory fitness.A greater impairment of physical fitness in observed in children born very preterm (≤32 weeks of gestation).These findings might support the implementation of preventive strategies (e.g. fitness monitoring and exercise training) in preterm children since early childhood.

Cardiometabolic sex differences in adults born small for gestational age

Aim

This study aimed to assess the cardiometabolic sex similarities and differences in adults born small for gestational age.

Methods

This study was an ambispective cohort study from a birth registry in Barcelona, Spain, including 523 adult participants (20-40 years-old) subdivided as born small for gestational age (SGA, if birth weight <10th centile) or adequate fetal growth for gestational age (AGA). Cardiometabolic health was assessed by echocardiography, electrocardiogram, blood pressure measurement, vascular ultrasound, anthropometric measurements, and serum glycemia and lipid profile. Stratified analyses by sex were performed by estimation of adjusted absolute difference (AAD) using inverse probability weighting.

Results

Compared with AGA, the stratified analyses by sex showed a more pronounced reduction in ejection fraction [AAD: female -1.73 (95% CI -3.2 to -0.28) vs. male -1.33 (-3.19 to 0.52)] and increment in heart rate [female 3.04 (0.29-5.8) vs. male 2.25 (-0.82 to 5.31)] in SGA females compared with SGA males. In contrast, a more pronounced reduction in PR interval [female -1.36 (-6.15 to 3.42) vs. male -6.61 (-11.67 to -1.54)] and an increase in systolic blood pressure [female 0.06 (-2.7 to 2.81) vs. male 2.71 (-0.48 to 5.9)] and central-to-peripheral fat ratio [female 0.05 (-0.03 to 0.12) vs. male 0.40 (0.17-0.62)] were mainly observed in SGA male compared with SGA female.

Conclusions

Sex differences were observed in the effect of SGA on cardiometabolic endpoints with female being more prone to cardiac dysfunction and male to electrocardiographic, vascular, and metabolic changes. Future research including sex-stratification data is warranted.

Physical activity and associations with health-related quality of life in adults born small for gestational age at term: a prospective cohort study

BACKGROUND

Adults born small for gestational age (SGA) have increased risk of adverse health outcomes. Physical activity (PA) is a key determinant of health and health-related quality of life (HRQoL). We aimed to investigate if being born SGA at term is associated with lower objectively measured and self-reported PA during adulthood. We also examined if objectively measured and self-reported PA were associated with HRQoL.

METHODS

As part of the 32-year follow-up in the NTNU Low Birth Weight in a Lifetime Perspective study, SGA and non-SGA control participants wore two tri-axial accelerometers for seven days (37 SGA, 43 control), and completed the International Physical Activity Questionnaire (IPAQ) (42 SGA, 49 control) and the Short Form 36 Health Survey (SF-36) (55 SGA, 67 control). Group differences in objectively measured daily metabolic equivalent of task (MET) minutes spent sedentary (lying, sitting), on feet (standing, walking, running, cycling), on the move (walking, running, cycling) and running/cycling, and group differences in self-reported daily MET minutes spent walking and in moderate and vigorous PA were examined using linear regression. Associations with SF-36 were explored in a general linear model.

RESULTS

Mean (SD) daily MET minutes on the move were 218 (127) in the SGA group and 227 (113) in the control group. There were no group differences in objectively measured and self-reported PA or associations with HRQoL. In the SGA group, one MET minute higher objectively measured time on the move was associated with 4.0 (95% CI: 0.6-6.5, p = 0.009) points higher SF-36 physical component summary.

CONCLUSION

We found no differences in objectively measured and self-reported PA or associations with HRQoL between term-born SGA and non-SGA control participants in adulthood.

Benefits and harms associated with an increase in gestational diabetes diagnosis in Queensland, Australia: a retrospective cohort comparison of diagnosis rates, outcomes, interventions and medication use for two periods, 2011-2013 and 2016-2018, using a large perinatal database

OBJECTIVES

To assess benefits and harms arising from increasing gestational diabetes (GDM) diagnosis, including for women with normal-sized babies.

DESIGN, SETTING AND PARTICIPANTS

Diagnosis rates, outcomes, interventions and medication use are compared in a retrospective cohort study of 229 757 women birthing in public hospitals of the Australian State of Queensland during two periods, 2011-2013 and 2016-2018, using data from the Queensland Perinatal Data Collection.

OUTCOME MEASURES

Comparisons include hypertensive disorders, caesarean section, shoulder dystocia and associated harm, induction of labour (IOL), planned birth (PB), early planned birth <39 weeks (EPB), spontaneous labour onset with vaginal birth (SLVB) and medication use.

RESULTS

GDM diagnosis increased from 7.8% to 14.3%. There was no improvement in shoulder dystocia associated injuries, hypertensive disorders or caesarean sections. There was an increase in IOL (21.8%-30.0%; p<0.001), PB (36.3% to 46.0%; p<0.001) and EPB (13.5%-20.6%; p<0.001), and a decrease in SLVB (56.0%-47.3%; p<0.001). Women with GDM experienced an increase in IOL (40.9%-49.8%; p<0.001), PB (62.9% to 71.8%; p<0.001) and EPB (35.3%-45.7%; p<0.001), and a decrease in SLVB (30.01%-23.6%; p<0.001), with similar changes for mothers with normal-sized babies. Of women prescribed insulin in 2016-2018, 60.4% experienced IOL, 88.5% PB, 76.4% EPB and 8.0% SLVB. Medication use increased from 41.2% to 49.4% in women with GDM, from 3.2% to 7.1% in the antenatal population overall, from 3.3% to 7.5% in women with normal-sized babies and from 2.21% to 4.38% with babies less than the 10th percentile.

CONCLUSION

Outcomes were not apparently improved with increased GDM diagnosis. The merits of increased IOL or decreased SLVB depend on the views of individual women, but categorising more pregnancies as abnormal, and exposing more babies to the potential effects of early birth, medication effects and growth limitation may be harmful.

Preterm Birth, Small for Gestational Age, and Large for Gestational Age and the Risk of Atrial Fibrillation Up to Middle Age

Importance

Adverse birth outcomes, including preterm birth, small for gestational age (SGA), and large for gestational age (LGA) are associated with increased risks of hypertension, ischemic heart disease, stroke, and heart failure, but knowledge regarding their associations with atrial fibrillation (AF) is limited and inconsistent.

Objective

To investigate whether preterm birth, SGA, or LGA are associated with increased risks of AF later in life.

Design, Setting, and Participants

This multinational cohort study included Danish, Swedish, and Finnish national health registries. Live singleton births in Denmark from 1978 through 2016, in Sweden from 1973 through 2014, and in Finland from 1987 through 2014, who were followed up until December 31, 2016, in Denmark, December 31, 2021, in Sweden, and December 31, 2014, in Finland were included. Data analyses were performed between January 2021 and August 2022.

Exposures

Preterm birth (less than 37 gestational weeks), SGA (less than 10th percentile birth weight for gestational age), and LGA (more than 90th percentile birth weight for gestational age) identified from medical birth registers.

Main Outcomes and Measures

Diagnosis of AF obtained from nationwide inpatient and outpatient registers. The study team ran multivariable Cox proportional hazard models and flexible parametric survival models to estimate hazard ratios (HRs) and 95% CIs for AF according to preterm birth, SGA, and LGA. Sibling analyses were conducted to control for unmeasured familial factors.

Results

The cohort included 8 012 433 study participants (maximum age, 49 years; median age, 21 years; male, 51.3%). In 174.4 million person-years of follow-up, 11 464 participants had a diagnosis of AF (0.14%; median age, 29.3 years). Preterm birth and LGA were associated with increased AF risk in both the full population cohort and in the sibling analyses; the multivariate HRs from the cohort analyses were 1.30 (95% CI, 1.18-1.42) and 1.55 (95% CI, 1.46-1.63), respectively. Preterm birth was more strongly associated with AF in childhood than in adulthood. Children born SGA had an increased risk of AF in the first 18 years of life but not afterwards.

Conclusions and Relevance

Preterm births and LGA births were associated with increased risks of AF up to middle age independently of familial confounding factors. Individuals born SGA had an increased AF risk only during childhood.

Body composition and physical fitness in adults born small for gestational age at term: a prospective cohort study

There is lack of research on body composition and physical fitness in individuals born small for gestational age (SGA) at term entering mid-adulthood. We aimed to investigate these outcomes in adults born SGA at term. This population-based cohort study included 46 adults born SGA with birth weight < 10th percentile at term (gestational age ≥ 37 weeks) (22 women, 24 men) and 61 adults born at term with birth weight ≥ 10th percentile (35 women, 26 men) at 32 years. Body composition was examined anthropometrically and by 8-polar bioelectrical impedance analysis (Seca® mBCA 515). Fitness was measured by maximal isometric grip strength by a Jamar hand dynamometer, 40-s modified push-up test and 4-min submaximal step test. Participants born SGA were shorter than controls, but other anthropometric measures did not differ between the groups. Men born SGA had 4.8 kg lower grip strength in both dominant (95% CI 0.6 to 9.0) and non-dominant (95% CI 0.4 to 9.2) hand compared with controls. Grip strength differences were partly mediated by height. In conclusion, body composition and physical fitness were similar in adults born SGA and non-SGA at term. Our finding of reduced grip strength in men born SGA may warrant further investigation.

Comparison of polysomnographic characteristics between low birthweight and normal birthweight children in the Northern Territory of Australia: A case-control study

OBJECTIVES

To describe the sleep architecture of pediatric patients according to whether they were born low birthweight (birthweight <2500 g, LBW) or normal birthweight (birthweight >2500 g).

DESIGN

Case control study.

SETTING

Pediatric sleep laboratory in the Northern Territory of Australia during a 5-year study period (2015- 2020).

PARTICIPANTS

Pediatric patients (aged <18 years) referred to the specialist sleep service for assessment of clinically suspected sleep disorders.

MEASUREMENTS

Sleep onset latency, rapid eye movement (REM) sleep latency, wake time after sleep onset, total sleep time, sleep efficiency, non-rapid eye movement stages N1/N2/N3, and REM sleep duration, total/spontaneous/respiratory/limb related arousal indexes, total/non-rapid eye movement/REM obstructive apnea-hypopnea index and oxygen saturation.

RESULTS

One hundred and seventy-two pediatric patients had birthweight data available of whom 19 were LBW. LBW patients showed significantly greater sleep disruption and higher prevalence of poor sleepers (<80% efficiency). In multivariate regression models, increasing birthweight was associated with significantly greater sleep efficiency and total sleep time. After accounting for gestational age LBW was associated with increased odds of obstructive sleep apnea.

CONCLUSIONS

Among pediatric patients LBW is associated with increased sleep disruption and reduced sleep efficiency. This is attenuated by gestational age, though both gestational age and LBW significantly influence odds of obstructive sleep apnea. This sleep health deficit may contribute to development of chronic disease in this vulnerable population, and should be monitored to provide avenues for early intervention.

Health-related quality of life in young adults born small for gestational age: a prospective cohort study

Background

Individuals born small for gestational age (SGA) have an increased risk of several adverse health outcomes, but their health-related quality of life (HRQoL) across young adulthood has yet to be studied. The main aim of this study was to investigate if being born SGA at term is associated with poor HRQoL at 32 years of age. A second aim was to explore longitudinal changes in HRQoL from age 20 to 32 years.

Methods

In the prospective NTNU Low Birth Weight in a Lifetime Perspective study, 56 participants born SGA and 68 non-SGA control participants completed the Short Form 36 Health Survey (SF-36) at age 32 years to assess HRQoL. The SF-36 was also administrated at age 20 and 28 years. Longitudinal changes in the eight SF-36 domains and the two component summaries from 20 to 32 years were analyzed by linear mixed models. In total, 82 adults born SGA and 98 controls participated at least once and were included in the longitudinal analyses.

Results

At age 32 years the participants born SGA scored 14.8 (95% CI 4.7 to 25.3) points lower in the SF-36 role-physical domain compared with the control group, i.e. more problems with work or other daily activities due to physical health problems. The longitudinal analyses showed significant group differences from 20 to 32 years in the role-emotional domain, and in the physical and mental component summaries. Among participants born SGA, the physical component summary decreased from age 20 to 28 years (-3.2, 95% CI -5.0 to -1.8), while the mental component summary (6.0, 95% CI 2.9 to 8.6) and role-emotional domain score (19.3, 95% CI 9.9 to 30.3) increased, but there were no further changes from 28 to 32 years. There were no longitudinal changes in the control group from 20 to 32 years.

Conclusion

Overall, individuals born SGA at term reported similar HRQoL at age 32 years compared with non-SGA controls. Self-perceived mental health improved during young adulthood among individuals born SGA, while self-perceived physical health deteriorated. The latter findings warrant further investigation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12955-022-01948-4.

The association between birth by cesarean section and adolescent cardiorespiratory fitness in a cohort of 339,451 Swedish males

Birth by cesarean section is increasing worldwide and associates with offspring morbidities capable of adversely impacting cardiorespiratory fitness later in life. Whether birth by cesarean section associates with lower levels of cardiorespiratory fitness later in life is unknown and is of interest to public health. Four Swedish national registers were linked to follow 339,451 singleton males, born between 1973–1987 until December 31 2005, for Watt-maximum achieved on a cycle ergometer test at conscription into the Swedish military. Main exposure was birth by cesarean section which was compared to vaginal birth. A sub-population of 45,999 males born between 1982–1987 was identified to explore differentiated associations between elective and non-elective cesarean section with Watt-maximum. Within-family analyses of 34,252 families with 70,632 biological male siblings, who conscripted during the study period, were performed to explore the role of familial confounding on Watt-maximum. Swedish males born by cesarean section achieved lower mean Watt-maximum (− 2.32 W, 95%C.I. − 2.90 to − 1.75) and displayed excess odds of low cardiorespiratory fitness (aOR = 1.08, 95%C.I. 1.05 to 1.11) at conscription in the eighteenth life-year compared to males born vaginally after adjusting for birth characteristics, maternal morbidities and parental socioeconomic position. In the sub-population, males born 1982–1987, there was a greater negative association of elective cesarean section with cardiorespiratory fitness (− 4.42 W, 95%C.I. − 6.27 to − 2.57, p < 0.001) than non-elective cesarean sections (− 1.96 W, 95%C.I. − 3.77 to − 0.16, p = 0.033) as compared to vaginal births. No associations between modes of cesarean delivery and cardiorespiratory fitness levels persisted in the within-family analyses where biological male siblings were compared whilst controlling for factors shared within families. Males born by cesarean section had lower levels of cardiorespiratory fitness eighteen years later compared to males born vaginally. These findings appear to be largely explained by factors of familial confounding.

Birth Weight and Cardiorespiratory Fitness Among Young Men Born at Term: The Role of Genetic and Environmental Factors

Background Preterm delivery and low birth weight are prospectively associated with low cardiorespiratory fitness (CRF). However, whether birth weight, within the at-term range, is associated with later CRF is largely unknown. Thus, the aim of the current study was to examine this issue and whether such association, if any, is explained by shared and/or nonshared familial factors. Methods and Results We conducted a prospective cohort study, including 286 761 young male adults and a subset of 52 544 siblings born at-term. Objectively measured data were retrieved from total population registers. CRF was tested at conscription and defined as the maximal load obtained on a cycle ergometer. We used linear and nonlinear and fixed-effects regression analyses to explore associations between birth weight and CRF. Higher birth weight, within the at-term range, was strongly associated with increasing CRF in a linear fashion. Each SD increase in birth weight was associated with an increase of 7.9 (95% CI, 7.8-8.1) and 6.6 (95% CI; 5.9-7.3) Wmax in the total and sibling cohorts, respectively. The association did not vary with young adulthood body mass index. Conclusions Birth weight is strongly associated with increasing CRF in young adulthood among men born at-term, across all categories of body mass index. This association appears to be mainly driven by factors that are not shared between siblings. Hence, CRF may to some extent be determined already in utero. Prevention of low birth weight, also within the at-term-range, can be a feasible mean of increasing adult CRF and health.