Secular change in size at birth from 1973 to 2003: national data from Denmark

Birthweights at term have increased globally: insights from a systematic review of 183 million births

OBJECTIVE

This study aimed to assess global trends in mean birthweights at term, as reported in peer-reviewed literature.

DATA SOURCES

We electronically searched PubMed, Embase, and Web of Science up to September 2023, using combinations of the search terms: "birth weight"; "birth-weight"; "birthweight"; "trend". There were no restrictions based on language or geographic area.

STUDY ELIGIBILITY CRITERIA

We included all ecological and observational studies reporting mean birthweight at term as a continuous numerical variable over time.

METHODS

We assessed the quality of included studies using the Dufault and Klar checklist modified by Betran et al. Univariate and multivariate linear models were used to examine the effects of time (years) and geographical origins. Subgroup analyses focused on national data sources and on data collected from 1950 onward.

RESULTS

Among 6447 reviewed articles, 29 met our criteria, reporting mean birthweight data from over 183 million infants worldwide. Most studies were hospital-based (48.3%), 44.8% used national data, and a minority used municipality, community, or regional data (6.9%). Geographically, North America (31.0%) had the highest representation, followed by Asia and Europe (27.6% each), and South America and Oceania (6.9% each). Our univariate linear regression model (Model 1) revealed a significant increase in mean birthweight at term over time (4.74 g/y; 95% confidence interval, 3.95-5.53; P<.001). Model 2, incorporating continental dummy variables into the first model, confirmed this trend (3.85 g/y; 95% confidence interval, 2.96-4.74; P<.001). Model 3, focusing on available national data, did not find a significant relationship. Model 4 narrowed its focus on records from 1950 onward, reporting a robust annual increase of 7.26 g/y (95% confidence interval, 6.19-8.33; P<.001). Model 5, adjusting for the number of participants included in each study, reported a conclusive mean term birthweight increase of 1.46 g/y (95% confidence interval, 0.74-2.18; P<.001).

CONCLUSION

This systematic review of 29 studies shows an increase in term birthweights over time, particularly when considering data since 1950. Limitations include study quality variations, data source diversity, and data sparsity, underscoring the need for future research to use precise gestational age distinctions and predetermined time frames to gain a deeper understanding of this trend and its implications for maternal and child health.

Birthweight trends and their explanatory factors in Hungary between 1999 and 2018: an analysis of the Hungarian Tauffer registry

BACKGROUND

The increasing birthweight trend stopped and even reversed in several high income countries in the last 20 years, however the reason for these changes is not well characterized. We aimed to describe birthweight trends of term deliveries in Hungary between 1999 and 2018 and to investigate potential maternal and foetal variables that could drive these changes.

METHODS

We analysed data from the Hungarian Tauffer registry, a compulsory anonymized data collection of each delivery. We included all singleton term deliveries in 1999-2018 (n = 1,591,932). We modelled birthweight trends separately in 1999-2008 and 2008-2018 in hierarchical multiple linear regression models adjusted for calendar year, newborn sex, maternal age, gestational age at delivery, and other important determinants.

RESULTS

Median birthweights increased from 3250/3400 g (girl/boy) to 3300/3440 g from 1999 to 2008 and decreased to 3260/3400 g in 2018. When we adjusted for gestational age at delivery the increase in the first period became more pronounced (5.4 g/year). During the second period, similar adjustment substantially decreased the rate of decline from 2.5 to 1.4 g/year. Further adjustment for maternal age halved the rate of increase to 2.4 g/year in the first period. During the second period, adjustment for maternal age had little effect on the estimate.

CONCLUSIONS

Our findings of an increasing birthweight trend (mostly related to the aging of the mothers) in 1999-2008 may forecast an increased risk of cardiometabolic diseases in offsprings born in this period. In contrast, the decreasing birthweight trends after 2008 may reflect some beneficial effects on perinatal morbidity. However, the long-term effect cannot be predicted, as the trend is mostly explained by the shorter pregnancies.

Association of Triglyceride-Glucose Index with Risk of Large for Gestational Age: A Prospective Cohort Study

Background

To evaluate the association of the baseline triglyceride-glucose (TyG) index in the first trimester of pregnancy with the risk of large for gestational age (LGA) in Southeast Chinese pregnant women.

Methods

A prospective birth cohort study recruiting 12,108 pregnant women at their first prenatal visit before 13 gestation weeks was conducted in 2019-2022. Baseline characteristics were collected from medical records or using questionnaires and blood samples were collected in the first trimester. The TyG index was obtained through the formula: ln[triglyceride (mg/dl)×fasting plasma glucose (mg/dl)/2]. The binary logistic regression model was performed to calculate the odds ratio (OR) and 95% confidence intervals (CI) to reveal the relationship between TyG index and LGA. Receiver-operating characteristic curve analysis was conducted to evaluate the ability of the TyG index to predict the risks of LGA.

Results

The overall incidence of LGA in the current study was 11.4% and the incidence of LGA increased with the baseline TyG index increasing. The risk of LGA was 2.05 (1.64, 2.57) for per unit increase in baseline TyG index. The increasing trend was found across the TyG index quartiles and the highest TyG quartiles raised the risk of LGA to 1.86 (95% CI: 1.51, 2.27) compared to the bottom TyG quartiles after full adjustment. The risk of LGA remained positive after stratification analysis. The AUC was 0.584 (95% CI: 0.569~0.600) in the entire subject, and the threshold was 8.34, with a sensitivity of 0.74 and specificity of 0.38.

Conclusion

The findings suggested that a higher TyG index in the first trimester was independently associated with higher risk of LGA and high TyG index in the first trimester may play as a early predictor for LGA.

Secular Trends of Birth Weight in Twins and Singletons in South Korea from 2000 to 2020

Whether the decline of birth weight (BW) reported in developed countries in the early 2000s is ongoing remains unknown. Furthermore, despite recent sharp increases in twin births, comparing secular trends of BW between singletons and twins is difficult, as studies have rarely examined secular trends of BW in twins and singletons simultaneously. Therefore, this study aimed to investigate the most recent 20-year trends (2000-2020) of BW in twins and singletons in South Korea. Annual natality files from 2000 to 2020 obtained from the Korean Statistical Information Service were analyzed. A yearly decrease of BW was 3 g among singletons and 5 to 6 g in twins from 2000 to 2020, indicating a widening gap of BW between twins and singletons with increasing years. Gestational age (GA) also decreased in twins and singletons with yearly decreases of 0.28 days in singletons and 0.41 days in twins. Whereas BW decreased in term (GA ≥ 37 weeks), and very preterm groups (28 weeks ≤ GA < 32 weeks) from 2000 to 2020 in twins and singletons, it increased in moderate to late preterm (32 weeks ≤ GA < 37 weeks) groups, indicating a non-linear relationship between BW and GA. The prevalence of macrosomia (BW > 4000 g) in singletons decreased from 2000 to 2020, whereas low birth weight (LBW; BW < 2500 g) increased in twins and singletons. LBW is associated with adverse health outcomes. Effective public health strategies aiming at reduction in the incidence of LBW in the population should be developed.

Birthweight and gestational age in the Faroe Islands: A comparison between birthweight and gestational age in the Faroe Islands and other Nordic countries

INTRODUCTION

This study aimed to examine Faroese infants' birthweight and gestational age in 2010-2019 and compare these findings with other Nordic countries. Risk factors for high birthweight among Faroese infants were also investigated in this study.

MATERIAL AND METHODS

All singleton liveborn infants registered in the Faroese Birth Registry in 2010-2019 were included in the study (n = 6121). A comparison was made with data on birthweight and gestational age from Denmark, Iceland, Norway, and Sweden.

RESULTS

The mean birthweight increased significantly from 3652 g (95% confidence interval [CI]: 3505-3699 g) in 2010 to 3745 g (95% CI: 3700-3790 g) in 2019, a mean increase in birthweight of 93 g (95% CI: 28-158 g) (p < 0.05). The birthweight increased 186 g (95% CI: 179-193 g) for each gestational week and 11 g (95% CI: 7-15 g) for each year. Changes in gestational age explained 31% of the change in birthweight. The proportion of infants weighing 4500 g or more increased significantly from 6.1% in 2010 to 9.6% in 2019 (p < 0.05). The risk of giving birth to an infant weighing 4000 g or more was consistently associated with previously giving birth (OR 1.98 (95% CI: 1.71-2.30)) and gestational age (OR 1.28 (95% CI: 1.23-1.33) per week increase in gestational age). Infants born in gestational weeks 40 and 42 in 2019 had a higher birthweight z-score than infants born in gestational weeks 40 and 42 in 2010. Compared to other Nordic countries, Faroese infants' mean birthweight was high, the Faroe Islands had a higher number of infants born with a weight of 4000 g or more and a higher proportion of infants born in gestational week 41 or later (31.5%).

CONCLUSIONS

Our results showed that the mean birthweight and the proportion of infants with high birthweight significantly increased during 2010-2019 in the Faroe Islands. The mean birthweight, the proportion of infants with high birthweight and the gestational age at birth for Faroese infants was higher than all other Nordic countries. The reasons for this require further investigation.

Risk factors combine in a complex manner in assessment for macrosomia

BACKGROUND

Macrosomia is a serious public health concern. This study aimed to examine the combined effects of various risk factors on macrosomia.

METHODS

The China Labor and Delivery Survey was a multicenter cross-sectional study that included 96 hospitals. Logistic regression analysis was performed to examine the combined effects of the risk factors for macrosomia. The population attributable risk percentage (PAR%) was calculated for the risk factors.

RESULTS

A total of 64,735 live births, including 3,739 neonates with macrosomia, were used for the analysis. The weighted prevalence of macrosomia was 5.8%. Pre-pregnancy overweight/obesity, diabetes, and gestational hypertension have a synergistic effect on increasing the rate of macrosomia in mothers aged < 36 years. The highest odds ratio (36.15, 95% CI: 34.38-38.02) was observed in female fetuses whose mothers had both gestational hypertension and diabetes. However, in mothers aged ≥ 36 years, the synergistic effect of gestational hypertension and other factors did not exist, and the risk for macrosomia was reduced by 70% in female fetuses of mothers with both gestational hypertension and overweight/obesity. Pre-pregnancy risk factors (pre-pregnancy overweight/obesity and advanced maternal age) contributed the most to macrosomia (23.36% of the PAR%), and the single largest risk factor was pre-pregnancy overweight/obesity (17.43% of the PAR%).

CONCLUSION

Macrosomia was related to several common, modifiable risk factors. Some factors have combined effects on macrosomia (e.g., pre-pregnancy overweight/obesity and diabetes), whereas gestational hypertension varies by maternal age. Strategies based on pre-pregnancy risk factors should be given more attention to reduce the burden of macrosomia.

Development of birthweight and length for gestational age and sex references in Yucatan, Mexico

OBJECTIVE

To develop sex- and gestational age specific reference percentiles and curves for birth weight and length for Yucatec neonates using data from birth registers of infants born during 2015-2019.

MATERIAL AND METHODS

Observational, descriptive, epidemiologic study in a 5-year period including every registered birth in the state of Yucatan, Mexico using birth registries. A total of 158 432 live, physically healthy singletons (76 442 females and 81 990 males) between 25 and 42 weeks of gestation were included in the analysis. We used the LMS method to construct smoothed reference centiles (3rd, 10th, 25th, 50th, 75th, 95th, and 97th) and curves for males and females separately.

RESULTS

Mean maternal age was 26 (SD = 6.22) years. Fifty-two percent of births occurred by vaginal delivery, 37% were firstborn and similar proportions were second (33%) and third or more (30%) born. 5.5% of newborns included in the references corresponds to neonates born before 37 weeks of gestation (5.9% boys and 5.1% girls). In both sexes, the percentage of infants with a birthweight less than 2500 g was 6.7%. The birthweight at the 50th percentile for males and females at 40 weeks of gestation in this cohort was 3256 and 3167 g, respectively, and the corresponding values for birth length were 50.23 and 49.84 cm (mean differences between sexes: 89 g and 0.40 cm, respectively).

CONCLUSION

The reference percentile and curves developed in this study are useful for research purposes and can help health practitioners to assess the biological status of infants born in Yucatán.

Pubarche and Gonadarche Onset and Progression Are Differently Associated With Birth Weight and Infancy Growth Patterns

Context

Controversy exists regarding associations between early-life growth patterns and timing of puberty.

Objective

This work aims to investigate associations between birth anthropometry, early growth patterns, and onset/progression of pubertal milestones in boys and girls.

Methods

Among children examined at birth (1997-2003) and at age 36 months in a mother-child cohort, pubertal Tanner stages (B1-5, PH1-5, G1-5) and testicular volume were examined by trained physicians at 1 to 5 follow-up examinations during childhood and adolescence (672 girls and 846 boys, 2006-2013).With parametric survival models we analyzed associations between birth weight, changes in SD scores (SDS) from birth to 36 months (ΔSDS 0-36 > 0.67 SD defining catch-up growth), and age at pubertal onset/attainment of late pubertal stages/menarche.

Results

A 1-kg higher birth weight was associated with earlier onset of B2+ (thelarche): -3.9 months (CI, -6.7 to -1.1 months), G2+ (gonadarche): -2.7 months (-5.3 to -0.1 months), Tvol3+ (testis size > 3 mL): -2.8 months (CI, -4.9 to -0.7 months), but with later G4+ and PH4+ in boys, and a slower progression from B2 to menarche (5.3 months [CI, 1.2 to 9.4 months]) in girls. Catch-up growth was associated with earlier PH2+ (pubarche) in girls (-4.1 months [CI, -7.6 to -0.6 months]), earlier PH2+ in boys (-3.4 months [CI, -6.6 to -0.2 months]), faster progression from B2 to menarche in girls (-9.1 months [CI, 14.6 to 3.5 months]), and earlier G4+ and PH4+ in boys.

Conclusion

Associations between birthweight and infancy catch-up growth differed for gonadarche and pubarche, and for early and late pubertal markers, with similar patterns in both sexes.

Low Birth Weight Increases the Risk of Sudden Cardiac Death in the Young: A Nationwide Study of 2.2 Million People

Background Sudden cardiac death (SCD) constitutes a major health problem worldwide. We investigated whether birth weight (BW), small for gestational age (SGA), and large for gestational age are associated with altered risk of SCD among the young (aged 1-36 years). Methods and Results We included all people born in Denmark from 1973 to 2008 utilizing the Danish Medical Birth Register. All SCDs in Denmark in 2000 to 2009 have previously been identified. We defined 5 BW groups, SGA, and large for gestational age as exposure and SCD as the outcome. We estimated the age-specific relative risk of SCD with 95% CI. Additionally, we investigated if SGA and large for gestational age are associated with pathological findings at autopsy. The study population for the BW analyses comprised 2 234 501 people with 389 SCD cases, and the SGA and large for gestational age analyses comprised 1 786 281 people with 193 SCD cases. The relative risk for SCD was 6.69 for people with BW between 1500 and 2499 g (95% CI, 2.38-18.80, P<0.001) and 5.89 for people with BW ≥4500 g (95% CI, 1.81-19.12, P=0.003) at age 5 years. BW 2500 to 3400 g was the reference group. Compared with an appropriate gestational age, the relative risk for SGA was 2.85 (95% CI, 1.35-6.00, P=0.006) at age 10 years. For the autopsied cases, the relative risk of sudden arrhythmic death syndrome at age 5 years was 4.19 for SGA (95% CI, 1.08-16.22, P=0.038). Conclusions We found an association between BW and SCD in the young, with an increased risk among SGA infants. In addition, we found an association between SGA and sudden arrhythmic death syndrome.

Increasing obstetric intervention for fetal growth restriction is shifting birthweight centiles: a retrospective cohort study

OBJECTIVE

To assess the impact of increasing obstetric intervention on birthweight centiles.

DESIGN

Retrospective cohort study of births in five 2-year epochs: 1983-84, 1993-94, 2003-2004, 2013-2014 and 2016-2017.

POPULATION

665 205 singleton births at ≥32 weeks' gestation.

SETTING

All maternity services in Victoria, Australia.

METHODS

For each epoch, we calculated the birthweight cutoffs defining each birthweight centile at 34, 37 and 40 weeks' gestation. We calculated rates of iatrogenic delivery over time. We then calculated the number of babies whose birthweight would have classified them as ≥3rd centile based on 1983-84 centile definitions but as <3rd centile based on 2016-2017 centile definitions.

MAIN OUTCOME MEASURES

Birthweight centile, and gestation at delivery.

RESULTS

From 1983-84 to 2016-2017, the rate of iatrogenic delivery for singleton pregnancies increased at all term gestations: 1.6-6.4% at 37 weeks', 4.5-18.3% at 38 weeks', 7.6-23.9% at 39 weeks' and 18.4-25.1% at 40 weeks' (all P < 0.001). Over the same period, the birthweight cutoffs defining the 3rd, 5th and 10th centiles increased significantly at term, but not preterm, gestations. This led to increasing numbers of term births being classified as small for gestational age (SGA). Of the 2748 babies born in 2016-2017 at 37-39 weeks' gestation with a birthweight <3rd centile in that period, 1478 (53.8%) would have been classified as ≥3rd centile based on 1983-84 centile definitions.

CONCLUSION

Increasing intervention is shifting the birthweight cutoffs that define birthweight centiles and thereby redefining what constitutes SGA. This undermines the use of population-derived birthweight centiles to audit clinical care.

TWEETABLE ABSTRACT

Increasing obstetric intervention is shifting birthweight centiles and therefore definitions of normality.

Large-for-gestational-age phenotypes and obesity risk in adulthood: a study of 195,936 women

While there is evidence that being born large-for-gestational-age (LGA) is associated with an increased risk of obesity later in life, the data are conflicting. Thus, we aimed to examine the associations between proportionality at birth and later obesity risk in adulthood. This was a retrospective study using data recorded in the Swedish Birth Register. Anthropometry in adulthood was assessed in 195,936 pregnant women at 10-12 weeks of gestation. All women were born at term (37-41 weeks of gestation). LGA was defined as birth weight and/or length ≥2.0 SDS. Women were separated into four groups: appropriate-for-gestational-age according to both weight and length (AGA - reference group; n = 183,662), LGA by weight only (n = 4,026), LGA by length only (n = 5,465), and LGA by both weight and length (n = 2,783). Women born LGA based on length, weight, or both had BMI 0.12, 1.16, and 1.08 kg/m² greater than women born AGA, respectively. The adjusted relative risk (aRR) of obesity was 1.50 times higher for those born LGA by weight and 1.51 times for LGA by both weight and height. Length at birth was not associated with obesity risk. Similarly, women born LGA by ponderal index had BMI 1.0 kg/m² greater and an aRR of obesity 1.39 times higher than those born AGA. Swedish women born LGA by weight or ponderal index had an increased risk of obesity in adulthood, irrespective of their birth length. Thus, increased risk of adult obesity seems to be identifiable from birth weight and ignoring proportionality.

Secular trends of birthweight in boys from 1950 to 2010

BACKGROUND

Birthweight is an indicator of fetal development and intrauterine conditions and is associated with future health outcomes. Secular birthweight trends prior to the 1970s are mostly unknown. Our aim was to explore secular birthweight trends in Swedish boys from 1950 to 2010.

METHODS

We have collected detailed growth data including birthweight from archived School Health Care records for children born in Gothenburg from 1946 and onwards and established a unique population-based cohort, the Body Mass Index Epidemiology Study (BEST). The birthweight cohort spans six decades (1950-2010) and includes 46,548 boys.

RESULTS

The mean birthweight of the complete study cohort was 3580 ± 562 g. Linear regression analysis of the entire period revealed a minimal negative secular trend for birthweight (BETA = -0.4 g/year; p < 0.01). However, three distinct trends appeared during sub-periods: a decrease 1950-80, an increase 1980-2000 and another decrease 2000-2010.

CONCLUSION

We demonstrate that birthweight in boys has undergone periodic decreases and subsequent increases, but the overall trend from the 1950s to the present is stable.

Genetic and environmental factors affecting birth size variation: a pooled individual-based analysis of secular trends and global geographical differences using 26 twin cohorts

Background

The genetic architecture of birth size may differ geographically and over time. We examined differences in the genetic and environmental contributions to birthweight, length and ponderal index (PI) across geographical-cultural regions (Europe, North America and Australia, and East Asia) and across birth cohorts, and how gestational age modifies these effects.

Methods

Data from 26 twin cohorts in 16 countries including 57 613 monozygotic and dizygotic twin pairs were pooled. Genetic and environmental variations of birth size were estimated using genetic structural equation modelling.

Results

The variance of birthweight and length was predominantly explained by shared environmental factors, whereas the variance of PI was explained both by shared and unique environmental factors. Genetic variance contributing to birth size was small. Adjusting for gestational age decreased the proportions of shared environmental variance and increased the propositions of unique environmental variance. Genetic variance was similar in the geographical-cultural regions, but shared environmental variance was smaller in East Asia than in Europe and North America and Australia. The total variance and shared environmental variance of birth length and PI were greater from the birth cohort 1990-99 onwards compared with the birth cohorts from 1970-79 to 1980-89.

Conclusions

The contribution of genetic factors to birth size is smaller than that of shared environmental factors, which is partly explained by gestational age. Shared environmental variances of birth length and PI were greater in the latest birth cohorts and differed also across geographical-cultural regions. Shared environmental factors are important when explaining differences in the variation of birth size globally and over time.

Estimating secular changes in longitudinal growth patterns underlying adult height with the QEPS model: the Grow Up Gothenburg cohorts

BACKGROUND

Over the past 150 years, humans have become taller, and puberty has begun earlier. It is unclear if these changes are continuing in Sweden, and how longitudinal growth patterns are involved. We aimed to evaluate the underlying changes in growth patterns from birth to adulthood by QEPS estimates in two Swedish cohorts born in 1974 and 1990.

METHODS

Growth characteristics of the longitudinal 1974 and 1990-birth cohorts (n = 4181) were compared using the QEPS model together with adult heights.

RESULTS

There was more rapid fetal/infancy growth in girls/boys born in 1990 compared to 1974, as shown by a faster Etimescale and they were heavier at birth. The laterborn were taller also in childhood as shown by a higher Q-function. Girls born in 1990 had earlier and more pronounced growth during puberty than girls born in 1974. Individuals in the 1990 cohort attained greater adult heights than those in the 1974 cohort; 6 mm taller for females and 10 mm for males.

CONCLUSION

A positive change in adult height was attributed to more growth during childhood in both sexes and during puberty for girls. The QEPS model proved to be effective detecting small changes of growth patterns, between two longitudinal growth cohorts born only 16 years apart.

Birth weight trends in England and Wales (1986-2012): babies are getting heavier

INTRODUCTION

Birth weight is a strong predictor of infant mortality, morbidity and later disease risk. Previous work from the 1980s indicated a shift in the UK towards heavier births; this descriptive analysis looks at more recent trends.

METHODS

Office for National Statistics (ONS) registration data on 17.2 million live, single births from 1986 to 2012 were investigated for temporal trends in mean birth weight, potential years of birth weight change and changes in the proportions of very low (<1500 g), low (<2500 g) and high (≥4000 g) birth weight. Analysis used multiple linear and logistic regression adjusted for maternal age, marital status, area-level deprivation and ethnicity. Additional analyses used the ONS NHS Numbers for Babies data set for 2006-2012, which has information on individual ethnicity and gestational age.

RESULTS

Over 27 years there was an increase in birth weight of 43 g (95% CI 42 to 44) in females and 44 g (95% CI 43 to 45) in males, driven by birth weight increases between 1986-1990 and 2007-2012. There was a concurrent decreased risk of having low birth weight but an 8% increased risk in males and 10% increased risk in females of having high birth weight. For 2006-2012 the birth weight increase was greater in preterm as compared with term births.

CONCLUSIONS

Since 1986 the birth weight distribution of live, single births in England and Wales has shifted towards heavier births, partly explained by increases in maternal age and non-white ethnicity, as well as changes in deprivation levels. Other potential influences include increases in maternal obesity and reductions in smoking prevalence particularly following the introduction of legislation restricting smoking in public places in 2007.

Concentration of 25-hydroxyvitamin D from neonatal dried blood spots and the relation to gestational age, birth weight and Ponderal Index: the D-tect study

Studies have suggested that vitamin D status at birth may be associated with a range of neonatal outcomes. The aim of this study was to assess the association between neonatal 25-hydroxyvitamin D3 (25(OH)D3) concentration and gestational age, birth weight, Ponderal Index and size for gestational age. Neonatal capillary blood stored as dried blood spots was used to assess 25(OH)D3 concentrations among 2686 subjects selected from a random population sub-sample of individuals, born in Denmark from 1 May 1981 to 31 December 2002. There was an inverse association between 25(OH)D3 concentration and gestational age at birth of -0·006 (95 % CI -0·009, -0·003, P<0·001) weeks of gestation per 1 nmol/l increase in 25(OH)D3 concentration. An inverted U-shaped association between 25(OH)D3 and birth weight and Ponderal Index (P=0·04) was found, but no association with size for gestational age was shown. This study suggests that neonatal 25(OH)D3 concentration is associated with anthropometric measures at birth known to be correlated with many subsequent health outcomes such as obesity and type 2 diabetes.

Trend and risk factors of low birth weight and macrosomia in south China, 2005-2017: a retrospective observational study

The percentages of low birth weight (LBW) increased from 7.7% in 2005 to 11.3% in 2011 and declined to 8.1% in 2017. For very low birth weight (VLBW) individuals, the proportion declined -1.0% annually, from 2.5% in 2005 to 1.4% in 2017. Among moderately low birth weight (MLBW) individuals, the proportion first increased 12.8% annually, from 5.0% in 2005 to 9.3% in 2011, and then declined -3.8% annually, from 9.4% in 2011 to 7.0% in 2017. The percentages of macrosomia monotone decreased from 4.0% in 2005 to 2.5% in 2017, an annual decline of -4.0%. Multiple regression analyses showed that boys, maternal age, hypertensive disorders complicating pregnancy (HDCP), and diabetes were significant risk factors for LBW. Boys, maternal age, gestational age, HDCP, diabetes, and maternal BMI were significant risk factors for macrosomia. Although the relevant figures declined slightly in our study, it is likely that LBW and macrosomia will remain a major public health issue over the next few years in China. More research aimed at control and prevention of these risk factors for LBW and macrosomia and their detrimental outcome in the mother and perinatal child should be performed in China.

Trends in Fetal Growth Between 2000 to 2014 in Singleton Live Births from Israel

Trends in birthweight and abnormal fetal growth, namely term low birthweight (LBW), macrosomia, small-for-gestational age (SGA) and large-for-gestational age (LGA), are important indicators of changes in the health of populations. We performed this epidemiological study to evaluate these trends among 2,039,415 singleton live births from Israel over a period of 15 years. Birth certificate data was obtained from the Ministry of Health. Multivariable linear and logistic regression models were used to evaluate crude and adjusted estimates compared to the baseline of 2000 and polynomial trends. During the study period we observed a significant decrease in the rates of infants born SGA and LGA (10.7% to 9.2%, 10.2% to 9.6% respectively). After adjustment, based on the imputed data set, term mean birthweight increased by 6.0 grams (95% CI: 2.9, 9.1), and term LBW odds decreased by 19% in 2014 compared to 2000 (adj ORs: 0.81; 95% CI: 0.77, 0.85). Significant decreases were also observed for adjusted SGA, LGA and macrosomia rates. The decrease in abnormal fetal growth rates were not entirely explained by changes in sociodemographic characteristics or gestational age and may imply real improvement in child intrauterine growth in Israel during the last 15 years, especially in the Jewish population.

SECULAR CHANGES IN BIRTH WEIGHTS AND WOMEN’S BODY SIZE IN KRAKÓW AND POZNAŃ (POLAND) DURING THE LAST CENTURY

Changing socioeconomic conditions over the last century have left their mark on neonatal size and final body size of individuals born in those days. The main aim of this study was to investigate how the historical, political and economic changes occurring from the late 19th century to the 2000s have affected the birth weight of newborns. Additionally, changes in weight and body height in the case of young women (potential mothers) were analysed. Data were from two cities in Poland (Kraków and Poznań) covering 15,884 newborns and 3612 women aged 18 years, derived from 1900 to 2010. Despite short-term fluctuations, the results showed significant increasing trends in all studied features. Changes in birth weight were similar in both cities: in Kraków it increased by 184 g (males) and 206 g (females), and in Poznań by 216 g (males) and 120 g (females). Changes in women’s body size were also significant, but the level was different depending on place of residence. In the last century, women’s body height increased by 8.2 cm in Kraków and by 10.2 cm in Poznań, and their body weight increased by 1 kg and 5 kg respectively. The considered period covered the years of socioeconomic change that occurred as a result of the political system transformation. Crises, periods of prosperity and other factors that determine standard of living and health care have influenced the development of the Polish population’s physical features.

Incidence of infants born small- and large-for-gestational-age in an Italian cohort over a 20-year period and associated risk factors

BACKGROUND

We assessed the incidence of infants born small-for-gestational-age (SGA) and large-for-gestational-age (LGA) in an Italian cohort over 20 years (1993-2013). Furthermore, we investigated maternal factors associated with SGA and LGA births.

METHODS

A retrospective review of obstetric records was performed on infants born in Chieti (Italy) covering every 5(th) year over a 20-year period, specifically examining data for 1993, 1998, 2003, 2008, and 2013. Infants with birthweight <10(th) percentile were defined as SGA, and those with birthweight >90(th) percentile as LGA. Data collected included newborn anthropometry, birth (multiple vs singleton), maternal anthropometry, previous miscarriage, gestational diabetes, hypertension, and smoking during pregnancy.

RESULTS

There were a pooled total of 5896 live births recorded across the 5 selected years. The number of SGA (+60.6 %) and LGA (+90.2 %) births increased considerably between 1993 and 2013. However, there were no marked changes in the incidence of SGA or LGA births (8.3 % and 10.8 % in 1993 versus 7.6 % and 11.7 % in 2013, respectively). Maternal factors associated with increased risk of SGA infants included hypertension, smoking, and previous miscarriage (all p < 0.05), while greater pre-pregnancy BMI and gestational diabetes were risk factors for LGA births (all p < 0.05).

CONCLUSIONS

There was an increase in the number of SGA and LGA births in Chieti over the last two decades, but there was little change in incidence over time. Most maternal factors associated with increased odds of SGA and LGA births were modifiable, thus incidence could be reduced by targeted interventions.

Race Disparities and Decreasing Birth Weight: Are All Babies Getting Smaller?

The mean infant birth weight in the United States increased for decades, but it might now be decreasing. Given race disparities in fetal growth, we explored race-specific trends in birth weight at Magee-Womens Hospital, Pittsburgh, Pennsylvania, from 1997 to 2011. Among singleton births delivered at 37-41 weeks (n = 70,607), we evaluated the proportions who were small for gestational age and large for gestational age and changes in mean birth weights over time. Results were stratified by maternal race/ethnicity. Since 1997, the number of infants born small for their gestational ages increased (8.7%-9.9%), whereas the number born large for their gestational ages decreased (8.9%-7.7%). After adjustment for gestational week at birth, maternal characteristics, and pregnancy conditions, birth weight decreased by 2.20 g per year (P < 0.0001). Decreases were greater for spontaneous births. Reductions were significantly greater in infants born to African-American women than in those born to white women (-3.78 vs. -1.88 per year; P for interaction = 0.010). Quantile regression models indicated that birth weight decreased across the entire distribution, but reductions among infants born to African-American women were limited to those in the upper quartile after accounting for maternal factors. Limiting the analysis to low-risk women eliminated birth weight reductions. Birth weight has decreased in recent years, and reductions were greater in infants born to African-American women. These trends might be explained by accumulation of risk factors such as hypertension and prepregnancy obesity that disproportionately affect African-American women. Our results raise the possibility of worsening race disparities in fetal growth.

Sex Differences in the Association Between Birth Weight and Adult Type 2 Diabetes

Low birth weight is a well-established risk factor for type 2 diabetes, but the risk at high birth weight levels remains uncertain. Potential sex differences in the associations are unexplored. We investigated whether sex influences the association of birth weight and adult type 2 diabetes, using a cohort of 113,801 men and 109,298 women, born 1936-1983, from the Copenhagen School Health Records Register, Denmark. During 5.6 million person-years of follow-up, 7,750 men and 4,736 women had a diagnosis of adult type 2 diabetes (30 years of age or older) obtained from national registers. When birth weights between 3.251 and 3.750 kg were used as the reference group for each sex separately, women with birth weights in the categories of 2.000 to 2.750 kg and 4.751 to 5.500 kg had hazard ratios [HRs] of type 2 diabetes of 1.46 (95% CI, 1.34-1.59) and 1.56 (1.20-2.04), respectively, whereas men had HRs of 1.20 (1.12-1.30) and 0.93 (0.76-1.15). Thus, sex modified the association, with stronger risk estimates of type 2 diabetes in women at both low and high birth weights compared with men (P = 0.001). In conclusion, birth weight is more strongly associated with type 2 diabetes in women than in men. Future search for sex-specific causal mechanisms may provide new insights into the early origins of type 2 diabetes.

Birth weight and childhood obesity: a 12-country study

OBJECTIVES

Few studies have investigated the association between the full range of birth weight and the risk of childhood obesity in high-, middle- and low-income countries. The aim of the present study is to assess the association between different levels of birth weight and the risk of obesity among children aged 9-11 years in 12 countries.

METHODS

A multinational, cross-sectional study of 5141 children aged 9-11 years was conducted in 12 countries. Height and weight were obtained using standardized methods. Time spent in moderate-to-vigorous physical activity (MVPA), sedentary and sleeping were objectively measured using 24-h, waist-worn accelerometer (Actigraph GT3X+) monitored for 7 days. Birth weight and other factors (regions, parental education, maternal history of gestational diabetes, children age, gender, breast feeding, gestational age, unhealthy diet scores and healthy diet scores) were collected by parental and children's questionnaires. Multilevel modeling was used to account for the nested nature of the data.

RESULTS

The overall prevalence of obesity (BMI z-score>+2 s.d.) was 15.4% for boys and 10.0% for girls. There was a positive association between birth weight and BMI z-scores. The multivariable-adjusted odds ratios (ORs) of childhood obesity were significantly higher among children whose birth weights were 3500-3999 g (OR 1.45; 95% confidence interval (CI): 1.10-1.92), and >4000 g (OR 2.08; 95% CI: 1.47-2.93), compared with the reference group (2500-2999 g). The positive association between birth weight and the odds of childhood obesity was seen in girls, whereas a U-shaped association appeared in boys.

CONCLUSIONS

High levels of birth weight, defined as birth weight ⩾3500 g, were associated with increased odds of obesity among 9-11-year-old children in 12 countries. However, sex differences in the association between birth weight and the risk of obesity need to be considered when planning interventions to reduce childhood obesity.

Changes in weight, length, head circumference, and ponderal index at birth of healthy term newborns in nine cities in China during the period of rapid social development 1985-2005

The changes in the anthropometric parameters at birth of healthy singleton term newborns in nine cities in China were analyzed by means of the data collected in three large-scale cross-sectional physical growth surveys in 1985, 1995, and 2005 (n=6660, 7109 and 6144). Between 1985 and 2005, average increases in body weight (BW), body length (BL), ponderal index (PI), and head circumference (HC) of newborns were statistically significant: 107g, 0.2cm, 0.6kg/m(3) and 0.4cm, respectively. The relative increase in BW was more than that in BL (3.4% vs 0.4%) in the last two decades, leading to an increase in PI. The distribution of birth size shifted slightly to the right, and the proportion of macrosomia increased from 3.2% in 1985 to 3.4% in 1995 and to 4.3% in 2005. The increases in BW and PI and the increase in rate of macrosomia are concerns from public health perspectives.

Fetal growth and subsequent maternal risk of colorectal cancer

BACKGROUND

High birth weight has been associated with subsequent increased risk of breast cancer in the infant's mother, possibly related to maternal estrogen and growth factor pathways. However, its association with maternal risk of colorectal cancer, the third most common cancer among women, is unknown.

METHODS

We conducted a national cohort study of 1,838,509 mothers who delivered 3,590,523 babies in Sweden in 1973-2008, followed up for colorectal cancer incidence through 2009.

RESULTS

There were 7,318 mothers diagnosed with colorectal cancer in 36.8 million person-years of follow-up. After adjusting for maternal age, body mass index, diabetes, and other potential confounders, high fetal growth was associated with a subsequent increased risk of colorectal cancer in the mother [incidence rate ratio (IRR) per additional 1 SD relative to mean birth weight for gestational age and sex, 1.05; 95% confidence intervals (CI), 1.03-1.07; P < 0.0001]. Each 1,000 g increase in the infant's birth weight was associated with a 12% increase in the mother's subsequent risk of colorectal cancer (IRR, 1.12; 95% CI, 1.07-1.17; P < 0.0001). Multiple gestation was also independently associated with increased maternal risk of colorectal cancer (IRR for twin or higher order vs. singleton, 1.22; 95% CI, 1.04-1.44; P = 0.02).

CONCLUSION

In this large cohort study, high fetal growth and multiple gestation were independently associated with subsequent higher maternal risk of colorectal cancer. These findings warrant further investigation of maternal growth factor and estrogen pathways in the etiology of colorectal cancer.

IMPACT

If confirmed, our findings may help identify subgroups of women at high risk of colorectal cancer.

Initial assessment and management of the newborn

This article summarizes the initial assessment of normal newborns and describes a few of the common variations that may occur. These variations require a pediatric provider to reassure anxious new parents and provide follow-up communication with the subsequent primary care provider.

Length and weight of newborns in Croatia from 1985 to 2009

BACKGROUND

Constitutional characteristics of humans are changing. People are becoming taller and they weigh more. These changes influence birth weight and birth length as well.

METHODS

A study was conducted on 2414 mothers and their newborns from 1985 to 2009 in Zagreb, Croatia, to establish a secular change in the weight and length of infants and the factors that are most related to these changes.

RESULTS

Birth weight has increased significantly in the past 25 years, and it is higher in male newborns. Taller mothers, with higher weight and body mass index, deliver newborns with higher birth weight. Weight gain in pregnancy has positive impact on birth weight. Multiparas and older and more educated women deliver newborns with higher weight. Birth weight does not depend on father's education. The number of newborns with birth weight more than 4000 g is increasing, but not significantly. Birth length was not significantly higher. Birth length is higher in male newborns, in newborns with higher birth weight and newborns of older and more educated mothers.

CONCLUSION

Better life conditions and better health care improves population constitutional characteristics that have implications in higher birth weight and birth length. This could be an important change that influences delivery modalities.

Aberrant upregulation of miR-21 in placental tissues of macrosomia

OBJECTIVE

With China's rapid economic growth in the past 3 decades, an increase in rate of macrosomia has been reported in China. Fetal growth is a result of multiple factors including genetic potential for growth, maternal nutrition, maternal metabolism, endocrine factors and placental perfusion and function. However, the detailed mechanism of how macrosomia happened remains poorly known. Recent studies showed that the expression of a number of microRNAs (miRNAs) in placentas is involved in fetal growth. We hypothesized that aberrant expression of microRNA-21 (miR-21) and microRNA-16 (miR-16) in placenta is associated with macrosomia.

STUDY DESIGN

Using quantitative real time PCR, we analyzed the expression level of miR-21 and miR-16 in terminal placentas of macrosomia pregnancies (n=35) and normal controls (n=35). Potential target genes of miRNA were predicted using TargetScan, miRanda and PicTar. Target genes were mapped to KEGG pathways using KEGG Mapper with an in-house Perl script with KEGG Gene IDs.

RESULT

MiR-21 showed significant up-regulation in macrosomia (P=0.037). After controlling the potential confounders, multivariable logistic regression analysis suggested the risk of macrosomia increased, multivariable adjusted ORs of macrosomia for those in the highest tertile was 3.931 (95%CI: 1.049-14.736) compared with those in the lowest tertile in terms of miR-21 level. The target genes of miR-21 were involved in eight possible signaling pathways. They were pathways in P53 signaling pathway, MAPK signaling pathway, HIF-1 signaling pathway, TGF-beta signaling pathway and PI3K-Akt signaling pathway (P<0.001), Wnt signaling pathway, Jak-STAT signaling pathway and mTOR signaling pathway (P<0.05).

CONCLUSION

Our study is the first to investigate the association between placental miRNA expression and macrosomia. Our results indicate that the expression level of miR-21 in placental tissue may be involved in the development of macrosomia.

Weight at birth and subsequent fecundability: a prospective cohort study

Objective

To examine the association between a woman's birth weight and her subsequent fecundability.

Method

In this prospective cohort study, we included 2,773 Danish pregnancy planners enrolled in the internet-based cohort study “Snart-Gravid”, conducted during 2007–2012. Participants were 18–40 years old at study entry, attempting to conceive, and were not receiving fertility treatment. Data on weight at birth were obtained from the Danish Medical Birth Registry and categorized as <2,500 grams, 2,500–2,999 grams, 3,000–3,999 grams, and ≥4,000 grams. In additional analyses, birth weight was categorized according to z-scores for each gestational week at birth. Time-to-pregnancy measured in cycles was used to compute fecundability ratios (FR) and 95% confidence intervals (CI), using a proportional probabilities regression model.

Results

Relative to women with a birth weight of 3,000–3,999 grams, FRs adjusted for gestational age, year of birth, and maternal socio-demographic and medical factors were 0.99 (95% CI: 0.73;1.34), 0.99 (95% CI: 0.87;1.12), and 1.08 (95% CI: 0.94;1.24) for birth weight <2,500 grams, 2,500–2,999 grams, and ≥4,000 grams, respectively. Estimates remained unchanged after further adjustment for markers of the participant's mother's fecundability. We obtained similar results when we restricted to women who were born at term, and to women who had attempted to conceive for a maximum of 6 cycles before study entry. Results remained similar when we estimated FRs according to z-scores of birth weight.

Conclusion

Our results indicate that birth weight appears not to be an important determinant of fecundability.

Perspectives on weight gain and lifestyle practices during pregnancy among women with a history of macrosomia: a qualitative study in the Republic of Ireland

BACKGROUND

Excessive weight gain during pregnancy is a major risk factor for macrosomia (high birth weight delivery). This study aimed to explore views about weight gain and lifestyle practices during pregnancy among women with a history of macrosomia.

METHODS

A qualitative descriptive study was conducted. Twenty-one second-time mothers whose first infant was macrosomic (>4 kg) were recruited from a randomised trial in a large maternity hospital in the Republic of Ireland. Semi-structured interviews were conducted with participants at both 6 and 12 months after their second pregnancy. Inductive thematic analysis was used to identify distinct themes.

RESULTS

The mothers believed in following their prenatal food cravings to meet their baby's needs, but this led some to eat excessively. Many of the women cut back heavily on physical activity during pregnancy due to perceived risks to the baby. Physical conditions and discomforts during pregnancy often limited maternal control over weight and lifestyle practices. The women were not particularly concerned about weight gain during pregnancy and most did not favour the notion of introducing weight gain guidelines into routine antenatal care. Common differences perceived by the women between their first and second pregnancy included: increased concern about weight gain in their second pregnancy due to prior difficulties with postpartum weight loss and increased time demands in their second pregnancy impeded healthy lifestyle practices. Most women did not alter their perspectives on weight gain and lifestyle practices in their second pregnancy in response to having a macrosomic infant in their first pregnancy.

CONCLUSIONS

This analysis exposed numerous barriers to healthy pregnancy weight gain. The findings suggest that women may need to be advised to follow their prenatal food cravings in moderation. Pregnant women with children already may benefit from education on time-efficient methods of integrating healthy eating practices and physical activity into their lifestyles. Women with a history of macrosomia may need information about the importance of avoiding high weight gain in subsequent pregnancies.

Maternal lipids and small for gestational age birth at term

OBJECTIVE

To compare maternal lipid and lipoprotein concentrations between small for gestational age (SGA) infants and infants with normal growth born at term.

STUDY DESIGN

This was a case-control study nested within a large (n = 5337) prospective multicenter cohort of pregnant women followed to delivery. SGA cases (n = 323) were all term infants with birth weight below the 10th percentile for their gestational age and sex. Controls (n = 671) were selected at random from term infants with birth weight between the 25th and 75th percentiles. Plasma samples obtained at 24-26 weeks were analyzed for lipoproteins using a recently developed nuclear magnetic resonance-based procedure that distinguishes high-density lipoprotein (HDL) and low-density lipoprotein particles of different sizes. Apolipoprotein A-1 and C-II levels were analyzed using turbidimetric methods.

RESULTS

Compared with controls, mothers of SGA cases had significantly higher mean concentrations of total HDL particles, medium and small HDL particles, and apolipoprotein A-1, with evidence of a dose-response relationship across quartiles of the control distribution. aORs for the highest quartiles were 2.8 (95% CI, 1.7-4.5) for total HDL particles and 3.1 (95% CI, 1.9-5.0) for apolipoprotein A-1.

CONCLUSION

Our results suggest that the higher HDL particle and apolipoprotein A-1 concentrations in mothers of SGA cases may reflect defective placental transport of HDL, which could compromise cholesterol uptake by the developing fetus.

New population-based references for birth weight, length, and head circumference in singletons and twins from 23 to 43 gestation weeks

BACKGROUND AND OBJECTIVES

Birth size curves are needed for clinical and epidemiological purposes. We constructed birth weight (BW), length (BL), and head circumference (BHC) references, assessed effects of twinness and parity, and defined cut-off points for small, appropriate, and large for gestational age.

MATERIALS AND METHODS

Birth register data of all 753,036 infants born in 1996-2008 in Finland were cleaned to create references reflecting optimal intrauterine growth. The final data included 533,666 singletons and 15,033 twins (median gestation weeks (gws) 40.0 and 37.1, respectively, 41.6% primiparous). Sex-specific BW, BL, and BHC references were constructed from 23 to 43 gws separately for singletons and twins born to primiparous or multiparous mothers. GAMLSS method was used for modelling.

RESULTS

In singletons from 36 gws onwards, increased BW and BL were observed in comparison to previous reference from 1979-1983. Twins diverged from singletons from 30 gws onwards. At 37.0 gws, mean BW was 400 g lower and mean BL 1.2 cm shorter than in singletons. From 30 gws onwards, birth size was larger in infants of multiparous than primiparous mothers.

CONCLUSIONS

Population-based birth size references are available for the evaluation of birth size. Accounting for plurality and parity improves the accuracy of birth size evaluation.

Radiographic fetal osteometry: approach on age estimation for the Portuguese population

The estimation of gestational age (GA) on fetal remains can be an important forensic issue. Forensic specialists usually use reference tables and regression equations derived from reference collections, which are quite rare in what fetuses are concerned. Since these tools are mostly grounded on ultrasonographic measurements, which are known to differ from real bones measurements or are based on ancient literature, this study aimed the construction of tables and regression equations for the Portuguese population on the basis of diaphyseal bone length measurements (femur, tibia and humerus) of 100 fetuses of known GA, using post-mortem radiographs. There is a strong correlation between the longitudinal length of studied bones and GA; the femur exhibits the strongest correlation (r=0.969; p=0.000), followed by the tibia (r=0.966; p=0.000) and the humerus (r=0.963; p=0.000). Therefore it was possible to obtain regression equations and to build tables with reference values for each of the diaphysis analyzed.

Neonatal anthropometrics and correlation to childhood obesity--data from the Danish Children's Obesity Clinic

Recent evidence has demonstrated the prenatal initiation of childhood obesity as epidemiological studies and animal studies have illustrated the effect of the intrauterine milieu for subsequent development of childhood obesity. This study investigates the relationship between severe childhood obesity and the preceding in utero conditions expressed by birth weight and birth length, birth-weight-for-gestational-age and neonatal ponderal index in a Danish cohort of 1,171 severely obese children (median age 11.48 years, range 3.13 to 17.98 years) with a mean body mass index-standard derivation score (BMI-SDS) of +2.96 (range +1.65 to +9.72) treated in our national referral centre. In a linear general regression model adjusted for socioeconomic status and breastfeeding duration, a significant linear correlation between BMI-SDS at time of enrolment and both birth weight (p, 3.8 × 10(-6)) and birth length (p, 6.1 × 10(-4)), birth-weight-for-gestational-age (p, 4.3 × 10(-7)) and the neonatal ponderal index (p, 0.02) was demonstrated. Duration of breastfeeding, however, was not found to be significant for either the BMI-SDS/BW or the BMI-SDS/BL correlation.

CONCLUSION

These results indicate that the prenatal period can be considered as a potential window of opportunity for prevention of childhood overweight and obesity and anthropological measurements may in theory be used to help identify neonates at high risk for developing childhood obesity.

Male specific association between xenoestrogen levels in placenta and birthweight

BACKGROUND

Fetal exposure to endocrine disrupting chemicals may increase the risk for adverse health effects at birth or later in life.

OBJECTIVES

The objective of this study is to analyze the combined effect of xenoestrogens on reproductive and perinatal growth outcomes (child birthweight, early rapid growth and body mass index (BMI) at 14 months) using the biomarker total effective xenoestrogen burden (TEXB).

METHODS

490 placentas were randomly collected in the Spanish prospective birth cohort Environment and Childhood (INMA) project. TEXB was used to assess the estrogenicity of placental samples in two fractions: that largely attributable to environmental organohalogenated xenoestrogens (TEXB-alpha), and that mostly due to endogenous estrogens (TEXB-beta), both expressed in estrogen equivalent units (Eeq) per gram of tissue. Linear or logistic regression models were performed adjusting for cohort and confounders. Sex interactions were investigated.

RESULTS

The median TEXB-alpha level was 0.76 pM Eeq/g (interquartile range (iqr): 1.14). In multivariate models, higher TEXB-alpha levels (third tertile, >1.22 pM Eeq/g; iqr: 1.73) were associated with increased birthweight in boys but not in girls (β=148.2 g, 95% CI: 14.01, 282.53, p(int)=0.057). Additionally, higher TEXB-alpha values in boys were related with a lower risk of early rapid growth (OR=0.37; 95% CI: 0.15, 0.88) and with a non significant association with larger BMI z-scores at 14 months of age (β=0.29; 95% CI: -0.11, 0.69).

CONCLUSIONS

These findings suggest that prenatal exposure to xenoestrogens may increase birthweight in boys, which might have an impact on child obesity and other later health outcomes.

Declines in birth weight and fetal growth independent of gestational length

OBJECTIVE

To estimate whether the decrease in birth weight of term singletons in the United States and elsewhere over the past decade, despite trends in common maternal characteristics expected to contribute toward an increase, is attributable to the simultaneous decrease in gestational length.

METHODS

Using data from Intermountain Healthcare, where a successful initiative reduced the number of early-term (37-38 weeks) elective deliveries, we examined trends in birth weight, being small for gestational age (SGA), and being large for gestational age (LGA) among 219,694 singleton neonates born between July 2000 and December 2008 at 37-41 weeks of gestation.

RESULTS

Over the 8.5 years, births through scheduled deliveries at 37-38 weeks decreased (9.7-4.4%), but overall scheduled deliveries increased (29-34%) and mean gestational age at birth (39.1 weeks) did not change. Mean birth weight (3,410-3,383 g) and LGA status (9.0-7.4%) both decreased, whereas SGA increased (7.5-8.2%). In multivariable analyses adjusting for maternal and newborn characteristics, birth weight decreased (-36 g; 95% confidence interval [CI] -31 to -42), especially among neonates born at 37-38 weeks of gestation (-40 g; 95% CI -30 to -49) or among those with medical indications for urgent deliveries (-48 g; 95% CI -34 to -63). Odds of being LGA decreased (0.77; 95% CI 0.73-0.82) and odds of being SGA increased (1.12; 95% CI 1.06-1.19).

CONCLUSION

Even in a population in which gestational length did not change, birth weight and fetal growth declined. Decrease not only in gestational length but also in fetal growth is likely to be contributing to the widely observed recent decrease in birth weight.

LEVEL OF EVIDENCE

I.

Pregestational body mass index is related to neonatal abdominal circumference at birth--a Danish population-based study

OBJECTIVES

To examine the impact of maternal pregestational body mass index (BMI) and smoking on neonatal abdominal circumference (AC) and weight at birth. To define reference curves for birth AC and weight in offspring of healthy, nonsmoking, normal weight women.

DESIGN

Population-based study.

SETTING

Data from the Danish Medical Birth Registry.

POPULATION

All live singletons without congenital malformations in Denmark 2004-10.

METHODS

Data on 366,886 singletons at 35(+0) to 41(+6) weeks(+days) of gestation were extracted and analysed using multivariate linear regressions.

MAIN OUTCOME MEASURES

Birth AC and weight in relation to pregestational maternal BMI, maternal smoking and medical conditions (any).

RESULTS

Birth AC and weight increased with increasing pregestational BMI, and decreased with smoking (P < 0.0001). Reference curves were created for offspring of healthy, nonsmoking mothers with normal pregestational BMI. Mean AC ranged from 30.1 cm and 30.2 cm at 35 weeks of gestation to 33.9 cm and 34.1 cm at 41 weeks of gestation, for girls and boys, respectively. Mean birthweight ranged from 2581 and 2666 g at 35 weeks to 3705 and 3852 g at 41 weeks of gestation for girls and boys, respectively. Pregestational BMI correlated more to the Z score of birthweight than to the Z score of AC (P < 0.0001).

CONCLUSION

Birth AC and weight are affected by maternal smoking status and pregestational BMI. Pregestational BMI correlated more to birthweight than to AC. Using data from healthy, nonsmoking mothers with normal pregestational BMI we have provided new reference curves for birth AC and birthweight.

Risk factors and long-term health consequences of macrosomia: a prospective study in Jiangsu Province, China

We sought to determine risk factors associated with fetal macrosomia and to explore the long-term consequence of infant macrosomia at the age of 7 years. A prospective population based cohort study was designed to examine the associations between maternal and perinatal characteristics and the risk of macrosomia. A nested case-control study was conducted to explore the long-term health consequence of infant macrosomia. The mean maternal age of the macrosomia group was 24.74±3.32 years, which is slightly older than that in the control group (24.35±3.14 years, P = 0.000). The mean maternal body mass index (BMI) at early pregnancy was 22.75±2.81 kg/m², which was also higher than that in the control group (21.76±2.59 kg/m², P = 0.000). About 64.6% of macrosomic neonates were males, compared with 51.0% in the control group (P = 0.000). Compared with women with normal weight (BMI: 18.5-23.9 kg/m²), women who were overweight (BMI: 24-27.9 kg/m²) or obese (BMI≥28 kg/m²), respectively, had a 1.69-fold (P = 0.000) and a 1.49-fold (P = 0.000) increased risks of having a neonate with macrosomia, while light weight (BMI<18.5 kg/m²) women had an approximately 50% reduction of the risk. Furthermore, macrosomia infant had a 1.52-fold and 1.50-fold risk, respectively, of developing overweight or obesity at the age of 7 years (P = 0.001 and P = 0.000). Older maternal age, higher maternal BMI at early pregnancy and male gender were independent risk factors of macrosomia. Macrosomic infant was associated with an increased predisposition to develop overweight or obesity at the beginning of their childhood.

Cord ghrelin levels are decreased in large-for-gestational-age neonates

Ghrelin is a growth hormone secretagogue peptide and has been recognized as an orexigenic factor. To investigate relationship between cord ghrelin and anthropometric and metabolic indices, we measured cord ghrelin in large-for-gestational-age (LGA) and appropriate-for-gestational-age (AGA) neonates and examined whether cord ghrelin levels were correlated to concentrations of cord blood glucose, insulin, lipid and maternal ghrelin. Fifty-five singletons born at term and their mothers were investigated in this study. Maternal venous blood samples were collected before delivery. Plasma concentrations of ghrelin, insulin, glucose, total cholesterol, triacylglycerol (TG), low-density lipoprotein-cholesterol (LDL-C) and high-density lipoprotein-cholesterol were measured in cord blood sampled at birth. The results show that the concentrations of cord ghrelin are significantly lower in LGA neonates. There is a positive correlation between cord ghrelin levels and maternal ghrelin levels. Negative correlations are found between cord ghrelin levels and gestational age, the concentrations of cord glucose, insulin, TG and LDL. Multivariate regression analyses show that birth weight (r(2)  = 0.674, β = -0.548, P < 0.001) was the predictor correlating with ghrelin levels. In conclusion, LGA neonates have lower cord ghrelin concentrations than AGA neonates.

Secular trends of macrosomia in southeast China, 1994-2005

Background

The rate of macrosomia (birth weight≥4, 000 g) increased over the past four decades in many parts of the world. Macrosomia is associated not only with higher risks of maternal and neonatal complications but also with health risks in adulthood. We examined trends in neonatal macrosomia and large-for-gestational-age (LGA) births among singleton, live, term and postterm births (≥37 complete weeks' gestation) in southeast China from 1994 to 2005 and explored possible causes of the temporal trends.

Methods

Data from Perinatal Health Care Surveillance System in 12 cities and counties in southeast China were analyzed for trends in birth weight, neonatal macrosomia and LGA from 1994 to 2005. A total of 594, 472 singleton live births were included. We conducted multiple logistic regression analyses to relate these trends to changes in maternal and pregnancy characteristics.

Results

The rate of macrosomia rose from 6.00% in 1994 to 8.49% in 2000 and then levelled off to 7.83% in 2005. Similar trends were observed in mean birth weight. The incidence of LGA births increased continuously from 13.72% in 1994 to 18.08% in 2000, but the LGA rate remained relatively stable from 2002 to 2005. There was a decrease in gestational age and a significant increase in frequency of prelabor caesarean delivery from 1994 to 2005. In an adjusted multivariable model, the increase in LGA rate from 1994 to 2000 was associated with increasing net gestational weight gain, maternal age, maternal height and maternal education. But they didn't fully explain the increase. The trends of 2002-2005 LGA declined after adjusted for maternal and neonatal characteristics.

Conclusions

In southeast China, the incidence of macrosomia increased from 1994 to 2000 was mainly related to increasing net gestational weight gain. The incidence of macrosomia has levelled off in recent years partly due to increasing use of prelabor caesarean delivery and earlier delivery and partly due to moderation of gestational weight gain.

Birth weight and subsequent risk of obesity: a systematic review and meta-analysis

This report describes the association between birth weight (BW) and obesity. Screening of 478 citations from five electronic databases resulted in the inclusion of 33 studies, most of medium quality. The meta-analysis included 20 of these published studies. The 13 remaining articles did not provide sufficient dichotomous data and were systematically reviewed, revealing results consistent with the meta-analysis. Our results revealed that high BW (>4000 g) was associated with increased risk of obesity (odds ratio [OR], 2.07; 95% confidence interval [CI], 1.91-2.24) compared with subjects with BW ≤ 4000 g. Low BW (<2500 g) was associated with decreased risk of obesity (OR, 0.61; 95% CI, 0.46-0.80) compared with subjects with BW ≥ 2500 g. However, when two studies exhibited selection bias were removed, the results indicated no significant association between low BW and obesity (OR, 0.77; 95% CI, 0.58-1.04). Sensitivity analyses showed that differences in the study design, sample size and quality grade of the study had an effect on the low BW/obesity association, which low BW was not associated with the risk of obesity in cohort studies, studies with large sample sizes and studies with high quality grades. Pooled results were similar when normal birth weight (2500-4000 g) was used as the reference category. Subgroup analyses based on different growth and developmental stages (pre-school children, school children and adolescents) also revealed that high BW was associated with increased risk of obesity from childhood to early adulthood. No significant evidence of publication bias was present. These results suggest that high BW is associated with increased risk of obesity and may serve as a mediator between prenatal influences and later disease risk.

Birthweight and mortality in adulthood: a systematic review and meta-analysis

BACKGROUND

Small birth size may be associated with increased risk of cardiovascular diseases (CVD), whereas large birth size may predict increased risk of obesity and some cancers. The net effect of birth size on long-term mortality has only been assessed in individual studies, with conflicting results.

METHODS

The Meta-analyses of Observational Studies in Epidemiology (MOOSE) guidelines for conducting and reporting meta-analysis of observational studies were followed. We retrieved 22 studies that assessed the association between birthweight and adult mortality from all causes, CVD or cancer. The studies were systematically reviewed and those reporting hazard ratios (HRs) and 95% confidence intervals (95% CIs) per kilogram (kg) increase in birthweight were included in generic inverse variance meta-analyses.

RESULTS

For all-cause mortality, 36,834 deaths were included and the results showed a 6% lower risk (adjusted HR = 0.94, 95% CI: 0.92-0.97) per kg higher birthweight for men and women combined. For cardiovascular mortality, the corresponding inverse association was stronger (HR = 0.88, 95% CI: 0.85-0.91). For cancer mortality, HR per kg higher birthweight was 1.13 (95% CI: 1.07-1.19) for men and 1.04 (95% CI: 0.98-1.10) for women (P(interaction) = 0.03). Residual confounding could not be eliminated, but is unlikely to account for the main findings.

CONCLUSION

These results show an inverse but moderate association of birthweight with adult mortality from all-causes and a stronger inverse association with cardiovascular mortality. For men, higher birthweight was strongly associated with increased risk of cancer deaths. The findings suggest that birthweight can be a useful indicator of processes that influence long-term health.

Defining smallness for gestational age in the early years of the Danish Medical Birth Registry

Background

Being born small for gestational age (SGA) is associated with decreased insulin sensitivity and increased blood pressure in childhood, but the association with clinical disease in early adulthood is less certain. The Danish Medical Birth Registry has registered all births in Denmark since 1973, but due to variable data quality, data is most often used only from 1981 onwards, and birth registers in other countries may have similar problems for the early years. We wanted to examine whether the data can be used for identification of children born SGA and used in future research.

Methodology/Principal Findings

All persons born between 1974 and 1996 were identified in the Danish Medical Birth Registry (n = 1.704.890). Immigrants and children without data on gestational age and birth weight were excluded, and a total of 1.348.106 children were included in the analysis. The difference between the different variables used in the history of the registry were examined, and the quality of data in the birth registry from 1974-1981 was examined and compared to subsequent years.

Data on birth weight and gestational age in the early years of the registry is inconsistent, and the identification of children born SGA is inaccurate, with 49% false-positives. The biggest source of error is due to the rough and inaccurate intervals used for gestational age. By using –3 standard deviations as a cut-off for the identification of children born SGA, the number of false-positives was reduced to 9%, while the amount of false-negatives were increased.

Conclusion

Choosing –3 standard deviations for identifying children born SGA is a viable, though not optimal solution for identifying children born SGA. Overall the data in the registry is of sufficient quality to be used in further medical research.

Association of macrosomia with perinatal and postneonatal mortality among First Nations people in Quebec

BACKGROUND

High prevalence of infant macrosomia (up to 36%, the highest in the world) has been reported in some First Nations communities in the Canadian province of Quebec and the eastern area of the province of Ontario. We aimed to assess whether infant macrosomia was associated with elevated risks of perinatal and postneonatal mortality among First Nations people in Quebec.

METHODS

We calculated risk ratios (RRs) of perinatal and postneonatal mortality by birthweight for gestational age, comparing births to First Nations women (n = 5193) versus women whose mother tongue is French (n = 653 424, the majority reference group) in Quebec 1991-2000.

RESULTS

The prevalence of infant macrosomia (birthweight for gestational age > 90th percentile) was 27.5% among births to First Nations women, which was 3.3 times (confidence interval [CI] 3.2-3.5) higher than the prevalence (8.3%) among births to women whose mother tongue is French. Risk ratios for perinatal mortality among births to First Nations women were 1.8 (95% CI 1.3-2.5) for births with weight appropriate for gestational age, 4.1 (95% CI 2.4-7.0) for small-for-gestational-age (< 10th percentile) births and < 1 (not significant) for macrosomic births compared to births among women whose mother tongue is French. The RRs for postneonatal mortality were 4.3 (95% CI 2.7-6.7) for infants with appropriate-for-gestational-age birthweight and 8.3 (95% CI 4.0-17.0) for infants with macrosomia.

INTERPRETATION

Macrosomia was associated with a generally protective effect against perinatal death, but substantially greater risks of postneonatal death among births to First Nations women in Quebec versus women whose mother tongue is French.

Optimal dietary approaches for prevention of type 2 diabetes: a life-course perspective

In recent years, several alternative dietary approaches, including high-protein and low-glycaemic-load diets, have produced faster rates of weight loss than traditional low-fat, high-carbohydrate diets. These diets share an under-recognised unifying mechanism: the reduction of postprandial glycaemia and insulinaemia. Similarly, some food patterns and specific foods (potatoes, white bread, soft drinks) characterised by hyperglycaemia are associated with higher risk of adiposity and type 2 diabetes. Profound compensatory hyperinsulinaemia, exacerbated by overweight, occurs during critical periods of physiological insulin resistance such as pregnancy and puberty. The dramatic rise in gestational diabetes and type 2 diabetes in the young may therefore be traced to food patterns that exaggerate postprandial glycaemia and insulinaemia. The dietary strategy with the strongest evidence of being able to prevent type 2 diabetes is not the accepted low-fat, high-carbohydrate diet, but alternative dietary approaches that reduce postprandial glycaemia and insulinaemia without adversely affecting other risk factors.