Current growth status and metabolic parameters of Korean adolescents born small for gestational age: results from the Korea National Health and Nutrition Examination Surveys (KNHANES) 2010-2011

Directed acyclic graph helps to understand the causality of malnutrition in under-5 children born small for gestational age

OBJECTIVES

Small-for-gestational age (SGA) is a causal factor for malnutrition (undernutrition). The available evidence on this causal relationship is based on observational studies and suffers from confounding and collider biases. This study aimed to construct a theoretical causal model to estimate the effect of SGA on malnutrition in children aged less than 5 years.

METHODS

For the causal model, we designated term-SGA status as the exposure variable and malnutrition at 6 months to 5 years of age (diagnosed by World Health Organization criteria) as the outcome variable. Causal estimands were formulated for three stakeholders. A "rapid narrative review" methodology was adopted for literature synthesis. Studies (observational and randomized) listing the causal factors of malnutrition in children aged less than 5 years from the Indian subcontinent were eligible. Four databases (PubMed, Scopus, Web of Science, and ProQuest) were searched and restricted to the last 10 years (search date: December 15, 2023). Information about the causal factors (covariates) of malnutrition and study characteristics was extracted from the article abstracts. Next, a causal model in the form of a directed acyclic graph (DAG) (DAGitty software) was constructed by connecting exposure, outcome, and covariate nodes using the sequential causal criteria of temporality, face validity, recourse to theory, and counterfactual thought experiments.

RESULTS

The search yielded 4818 records, of which 342 abstracts were included. Most of the studies were conducted in India (39%) and Bangladesh (27%). The literature synthesis identified 81 factors that were grouped into 17 nodes, referring to 5 domains: socioeconomic, parental, child-related, environmental, and political. The DAG identified 12 different minimal sufficient adjustment sets (conditioning sets for regression analysis) to estimate the total effect of SGA on malnutrition.

CONCLUSION

We offer an evidence-based causal diagram that will minimize bias due to improper selection of factors in studies focusing on malnutrition in term-SGA infants. The DAG and adjustment sets will facilitate the design and data analysis of future studies.

Low birth weight and small for gestational age are associated with complications of childhood and adolescence obesity: Systematic review and meta-analysis

In recent decades, the incidence of type 2 diabetes (T2D) has increased dramatically in children and adolescents, posing a real public health problem. Beyond unhealthy diets and sedentary lifestyles, growing evidence suggests that some perinatal factors, such as low birth weight (LBW), are associated with higher risk of T2D in adulthood. In this regard, it remains unclear whether the increased risk is already present in childhood and adolescence. We conducted a systematic review and meta-analysis to clarify the association of LBW or being small for gestational age (SGA) with insulin resistance in childhood and adolescence. The systematic review resulted in 28 individual studies, and those with the same outcome were included within two random-effects meta-analyses. Compared with children or adolescents born with adequate size for gestational age, those SGA had 2.33-fold higher risk of T2D (95% confidence interval [CI]: 1.05-5.17). Furthermore, LBW and being SGA were associated with 0.20 higher mean homeostasis model assessment of insulin resistance (HOMA-IR) values (95% CI: 0.02-0.38). Given the high prevalence of preterm babies, from a population perspective, these results may be of great importance as they point to the existence of a potentially vulnerable subgroup of children and adolescents that could benefit from screening tests and early preventive strategies.

Eligibility for growth hormone therapy in children born small for gestational age is substantially lower than expected

BACKGROUND

Growth hormone therapy is indicated for children who are both born 'small for gestational age' (SGA) and do not achieve adequate catch-up growth (ACUG).

OBJECTIVE

To evaluate the actual incidence of infants born SGA and their actual ACUG.

METHODS

Birth weight data from the newborn registry at two hospitals were analysed during four consecutive years. SGA was defined according to WHO parameters and the corresponding Israeli criteria. Follow-up measurements of height and weight were abstracted from either the Ministry of Health-child growth follow-up centres, or their paediatrician clinic. ACUG was declared when the height reached was above -2.5 or -2 standard deviations (SDS) from the mean for age and gender.

RESULTS

Out of 43 307, only 524 babies in the cohort (1.2%) were SGA (52% of expected). This finding was consistent annually. Out of the 446 SGA born children with available growth data (85%) during 4-8 years, 405 children (90.8%) reached a height greater than -2SDS and 428 (96%!) reached a height greater than -2.5 SDS. Term children had higher rate of ACUG achievement as compared to preterm 97.2% vs 86.8% (P < .001). Birth week and birth weight were also related to achievement of ACUG (P < .001).

CONCLUSION

This large representative, heterogeneous and Western Caucasian cohort indicates that the actual number of SGA newborns is nearly half of the expected and that the actual prevalence of ACUG is also significantly higher than previously reported. These findings may have an impact on morbidity, health cost planning and growth hormone requirements in SGA babies.

Radiological screening of maternal periodontitis for predicting adverse pregnancy and neonatal outcomes

It is well known that periodontitis, diagnosed mainly by periodontal probing, is associated with adverse pregnancy outcomes. However, periodontal probing is time-consuming, highly discomforting, inaccurate, and invasive. We aimed to assess whether periodontitis severity based on radiological staging in accordance with the 2017 new consensus classification was related to adverse pregnancy and neonatal outcomes. The medical records of 165 mothers who underwent panoramic radiography within 5 years before and after the time of delivery and of their singleton neonates were retrospectively reviewed. Twenty-two mothers (13.3%) had severe periodontitis (SP), and 143 (86.7%) had mild or moderate periodontitis (MP). In relation to adverse pregnancy outcomes, uterine leiomyoma (18.2% vs. 4.2%, P = 0.029), chronic hypertension (9.1% vs. 0.7%, P = 0.047), and preeclampsia (13.6% vs. 2.1%, P = 0.032) occurred significantly more frequently in the SP group than in the MP group. The incidences of very preterm birth (13.6% vs. 1.4%, P = 0.017), extremely preterm birth (9.1% vs. 0.7%, P = 0.047), and small for gestational age (22.7% vs. 5.6%, P = 0.017) were also significantly higher in the SP group than in the MP group. Radiological screening of maternal periodontitis could be useful for predicting adverse pregnancy and neonatal outcomes as well as diagnosing SP in pregnant women.

Long-term care, from neonatal period to adulthood, of children born small for gestational age

Children born small for gestational age (SGA) face an increased risk of health problems in later life, particularly persistent short stature, neurocognitive dysfunction, impaired renal and pulmonary function, decreased bone density, sensorineural hearing loss, premature adrenarche, and metabolic syndrome. Insulin resistance appears to be a key component underlying these metabolic complications. Long-term, continuous, GH treatments in short children born SGA lead to a normalization of height through childhood to adulthood. Recombinant human GH has been proven to be relatively safe. We recommend early surveillance in a growth clinic for children born SGA without catch-up growth. Obesity, insulin resistance, and the risk of metabolic syndrome increase with catch-up growth, but short stature and cognitive dysfunction increase without catch-up growth in children born SGA. A solution to this catch-up dilemma is breast feeding for a minimum of 6 to 12 mo. Because the overall prevalence of metabolic risk factors is very low, routine evaluation of metabolic parameters is not recommended for all children born SGA, but it may be useful to consider metabolic evaluations in overweight or obese children born SGA. Since children born SGA have many risk factors, long-term management from neonate to adulthood is very important.

Blood Pressure Trajectories from Childhood to Adolescence in Pediatric Hypertension

It has been known for a long time that elevated blood pressure (BP) in the young may persist and progress into adult hypertension (HTN). Multiple studies have revealed the predicted BP trajectory lines starting from childhood and related them to later cardiovascular (CV) risks in adulthood. As a small baby grows into a tall adult, BP will also naturally increase. Among early-life predictors of adult HTN, birth history, such as prematurity, and low birth weight have been popular subjects in research on pediatric HTN, because body size at birth has been reported to be inversely related to the risk of adulthood HTN. The hypothesis of HTN in prematurely born adolescents has been postulated as a physiological predisposition to postnatal excessive weight gain. Current body weight is a well-known independent predictor of HTN in children, and some studies showed that children demonstrating upward crossing of their weight percentiles while growing into adolescents have significantly increased risk for elevated BP later in life. Recently, reports focused on the adverse effect of excessive catch-up growth in this population are gradually drawing attention. Accordingly, children born prematurely or with intrauterine growth restriction who show rapid changes in their weight percentile should be under surveillance with BP monitoring. Prevention of childhood obesity, along with special care for premature infants or infants small for their gestational age, by providing healthy nutritional guidelines should be cardinal strategies for the prevention of adult HTN and CV risks later in life.

Small for gestational age and obesity related comorbidities

Infant born small for gestational age (SGA) are at increased risk of perinatal morbidity, persistent short stature and metabolic alterations in later life. The result of SGA followed by rapid weight gain during early postnatal life has been associated with increased long-term risks for central obesity, insulin resistance, impaired glucose tolerance, type 2 diabetes, hypertension, increased fat mass, and cardiovascular disease. We should carefully monitor their weight during infancy and childhood to prevent excessive rates of weight gain. 'Healthy catch up growth' may decreased the risk of obesity-related comorbidities in SGA. Establishing the optimal growth patterns in SGA to minimize short- and long-term risks is important, and further studies will be needed. This review discusses recent studies concentrating on obesity-related morbidities in SGA infants that may provide insight into growth monitoring.

Small for gestational age and obesity: epidemiology and general risks

Children born small for gestational age (SGA) have several life-long consequences. Previous epidemiological studies investigated from childhood to adulthood reported that a number of chronic diseases originate in the prenatal period. With the emerging era of obesity epidemic, more concerns are related to being obese than being short-statured in SGA children. The exact mechanisms are uncertain; however, growth hormone-insulin-like growth factor axis disturbance by fetal programming and accelerated postnatal weight gain contributed to central adiposity in SGA children. In this review, we summarized the definitions and prevalence of SGA, epidemiology, and general risks of obesity in SGA children. Early interventions, before and after birth, are needed for healthy catch-up growth to prevent later obesity and related complications.

Catch-up growth and catch-up fat in children born small for gestational age

Infants born small for gestational age (SGA) are at increased risk of perinatal morbidity, persistent short stature, and metabolic alterations in later life. Recent studies have focused on the association between birth weight (BW) and later body composition. Some reports suggest that fetal nutrition, as reflected by BW, may have an inverse programing effect on abdominal adiposity later in life. This inverse association between BW and abdominal adiposity in adults may contribute to insulin resistance. Rapid weight gain during infancy in SGA children seemed to be associated with increased fat mass rather than lean mass. Early catch-up growth after SGA birth rather than SGA itself has been noted as a cardiovascular risk factor in later life. Children who are born SGA also have a predisposition to accumulation of fat mass, particularly intra-abdominal fat. It is not yet clear whether this predisposition is due to low BW itself, rapid postnatal catch-up growth, or a combination of both. In this report, we review the published literature on central fat accumulation and metabolic consequences of being SGA, as well as the currently popular research area of SGA, including growth aspects.