THE IMPACT OF EXCESSIVE BODY WEIGHT DURING PREGNANCY ON THE PHYSICAL DEVELOPMENT OF INFANTS

ABSTRACT

Excess body weight and obesity during pregnancy are currently considered one of the important perinatal problems of modern medicine. Scientific studies of recent years show that a high body mass index (BMI) during pregnancy increases the risk of such complications in the fetus as macrosomia, low birth weight, intrauterine growth restriction, as well as various metabolic changes. In addition, excess body weight in mothers also affects the process of breastfeeding, altering the composition of breast milk and the duration of lactation, which indirectly affects the processes of infant growth. This literature review analyzes scientific articles and studies published in the period 2015–2025, devoted to the impact of excessive body weight during pregnancy on the physical development of infants. Based on the studied literature sources, it is shown that maternal excess body weight is one of the important risk factors affecting the indicators of physical development of the fetus and newborn children.

АННОТАЦИЯ

Избыточная масса тела и ожирение во время беременности в настоящее время рассматриваются как одна из важных перинатальных проблем современной медицины. Научные исследования последних лет показывают, что высокий индекс массы тела (ИМТ) во время беременности повышает риск развития у плода таких осложнений, как макросомия, рождение с низкой массой тела, задержка внутриутробного роста, а также различные метаболические изменения. Кроме того, избыточная масса тела у матерей оказывает влияние и на процесс грудного вскармливания, изменяя состав грудного молока и продолжительность лактации, что косвенно влияет на процессы роста младенца. В данном обзоре литературы проанализированы научные статьи и исследования, опубликованные в период 2015–2025 гг., посвященные влиянию избыточной массы тела во время беременности на физическое развитие младенцев. На основе изученных литературных источников показано, что избыточная масса тела матери является одним из важных факторов риска, влияющих на показатели физического развития плода и новорожденных детей.

Keywords: pregnancy, body mass index, complications, infant

Ключевые слова: беременность, индекс массы тела, осложнения, младенец

Relevance of the topic. The prevalence of excess body weight and obesity in the world is steadily increasing: if in 2006 this indicator was 9.8%, then by 2016 it reached 13.2% and is currently approaching an epidemic level worldwide [1–3]. Currently, more than 50% of women of reproductive age are overweight or obese [1]. Worldwide, the problems of excess body weight during pregnancy, which are considered by healthcare institutions as a high-risk factor for mothers, are manifested by an increase in the frequency of perinatal and labor complications [2, 4, 8]. Especially in pregnant women with excess body weight, the most alarming pregnancy complications are recognized as hypertensive disorders of pregnancy (preeclampsia and gestational hypertension), gestational diabetes, large-for-gestational-age fetus, preterm birth, stillbirth and neonatal mortality, induction of labor due to weak labor activity, emergency cesarean section, postpartum hemorrhage and shoulder dystocia (impaction of the child’s shoulder in the maternal pelvis), which poses a serious threat to the health of the mother and child [8]. One of the simplest, fastest and most accessible methods for assessing and classifying a woman’s body weight is the body mass index (BMI) [3]. During pregnancy, due to an increase in the amount of fluid in the woman’s body, the relationship between BMI and disease risk may somewhat weaken. Nevertheless, BMI is widely used to identify and monitor obesity during pregnancy. The Institute of Medicine (IOM) has developed recommendations that determine the optimal weight gain during pregnancy.

According to these recommendations:
for women with obesity: 5–9 kg (11–20 pounds);
for overweight women: 6.8–11.3 kg (15–25 pounds).

However, the IOM recommendations are mainly based on observational studies conducted among women of European origin. Therefore, reliable data on the applicability of these recommendations to women of other nationalities and low-income groups are insufficient. For example, the National Institute for Health and Care Excellence (NICE) in the United Kingdom has not adopted these recommendations, since the available evidence is considered insufficiently reliable for clinical practice. Nevertheless, the IOM recommendations can serve as an important guideline for physicians in the management of pregnancy in women with obesity. Currently, experts of the World Health Organization (WHO) are discussing the need to revise the criteria for identifying pathological changes in body weight in pregnant women (Table 1), since at different stages of pregnancy, as well as depending on race and other factors, significant changes in the body composition of a woman may occur [5,6,7].

Table 1.

Indicators of weight gain in pregnant women depending on body mass index (WHO)

Pathophysiological basis of excessive body weight during pregnancy. Obesity during pregnancy manifests through a number of complex metabolic, hormonal, and inflammatory processes in the mother’s body. These processes have a significant impact not only on the metabolic state of the woman but also on placental function and fetal development. Normally, during pregnancy, the maternal body is physiologically prone to insulin resistance, since during this period a greater supply of glucose and other energy sources is required for fetal growth. However, in the presence of obesity in a woman, insulin resistance increases, which leads to elevated blood glucose levels and increases the risk of developing gestational diabetes. Studies show that the level of insulin resistance in women with obesity is significantly higher than in women with normal body weight, which leads to metabolic imbalance and, as a result, may contribute to the development of fetal macrosomia and complications of labor [9].

In the pathophysiology of obesity, an important role is played by the activity of adipose tissue as an endocrine organ, since adipocytes produce adipokines such as leptin, adiponectin, and resistin. In obesity during pregnancy, leptin levels increase while adiponectin levels decrease, which enhances metabolic and inflammatory processes. These changes disrupt placental function and the mechanisms of nutrient transport to the fetus [10]. In addition, in obesity, women develop chronic low-grade inflammation: the activity of macrophages in adipose tissue increases and the levels of inflammatory mediators such as TNF-α, IL-6, and C-reactive protein rise. These cytokines play a key role in impairing placental blood circulation and the development of endothelial dysfunction, which in turn increases the risk of preeclampsia, gestational hypertension, and other pregnancy complications [11]. In obese pregnant women, lipid metabolism is also disturbed: instead of physiological hypercholesterolemia, there is a significant increase in the levels of triglycerides and free fatty acids. These substances are able to pass through the placenta, altering fetal metabolism and creating prerequisites for the development of metabolic syndrome or obesity in the child in the future [12]. In addition, obesity increases oxidative stress in the placenta, which leads to impaired mitochondrial activity and changes in angiogenesis processes. As a result, placental blood flow and nutrient transport are disrupted, which may lead both to fetal growth restriction and, conversely, to the development of macrosomia [13].

The impact of maternal body weight on anthropometric indicators of the fetus and newborn. The study of the impact of excessive maternal body weight on children through observation of anthropometric indicators of newborns presents certain difficulties, since the assessment of growth based only on body weight may be insufficiently accurate. Therefore, to standardize observation criteria, the World Health Organization (WHO) has developed indicators that allow a more accurate assessment of child growth, in which age, body weight, and body length (from birth to two years, and then height) are used as the main parameters [4]. Studies have shown that the rate of gestational weight gain (GWG) is positively associated with body weight and BMI z-score in early infancy, but has no significant association with body length. It has been established that children of women who gained greater body weight during pregnancy have higher BMI z-score values, and this relationship is more pronounced in male newborns. In particular, studies conducted in China have shown that obesity among boys occurs almost twice as often as among girls, and its growth rate is also significantly higher [15]. In addition, the relationship between the rate of gestational weight gain and BMI z-score was more pronounced in the first and second trimesters of pregnancy. This indicates that preventive interventions aimed at preventing excessive gestational weight gain should begin in early pregnancy, and possibly even before its onset, as this may reduce the risk of excessive body weight or obesity in children in the future. A high maternal body mass index during pregnancy has a number of adverse effects on both the woman and the newborn. These include the birth of a child with a body weight exceeding the norm for gestational age, an increased likelihood of weak labor activity, difficulties in initiating breastfeeding for various reasons, persistent postpartum weight retention in the mother, as well as an increased frequency of pregnancy loss [16,17]. It is important to note that excessive body weight and obesity during pregnancy are associated with increased birth weight of the newborn, which may subsequently lead to the development of obesity at older ages [12]. However, not all effects of obesity during pregnancy, including its association with the birth of low birth weight infants (according to WHO definition, low birth weight is defined as birth weight less than 2500 g regardless of gestational age), have been conclusively and unequivocally proven [17,18,19]. Disorders associated with obesity, including chronic inflammation, oxidative stress, insulin resistance, dysregulation of neurohormones and cytokines, as well as epigenetic changes, affect placental function and its ability to transport nutrients [20,21]. Among the numerous processes observed in mothers with obesity, two opposing regulatory mechanisms have been identified [22]. Firstly, an increase in maternal levels of TNF-α, interleukin-6, insulin, and leptin may be associated with the risk of fetal hypertrophy. These biomarkers stimulate the activity of placental transport systems responsible for nutrient transfer [23]. Secondly, if maternal obesity is accompanied by an increase in interleukin-1β (which suppresses insulin-stimulated nutrient transport), as well as an increase in soluble FMS-like tyrosine kinase (sFLT) and a decrease in placental growth factor (PlGF), involved in angiogenesis processes, there is a reduction in placental blood flow. As a result, fetal growth slows down [18, 24,25].

It is known that breast milk has the ability to modify its composition, which is aimed at improving the health status of the infant. Maternal characteristics also influence these processes. Maternal characteristics may be one of the factors determining some of these changes [26]. Although excessive body weight and obesity in the mother are among the factors capable of altering the bioactive components of breast milk [18,21], there are regulatory mechanisms in the mammary gland that protect the infant from excessive exposure to components that may negatively affect health. For example, apocrine and merocrine secretion systems allow more effective regulation of substances entering the milk, and many bioactive components play an important role in the formation of adipose tissue and the regulation of hunger and satiety cycles [23,24,27]. According to studies, women were observed for 180 days under the condition of exclusive breastfeeding, and in order to determine the possible effect of breast milk on infant development, the process of exclusive breastfeeding was studied over these 180 days. Although no statistically significant differences in infant body weight (in grams) were found between mothers with excess body weight/obesity and mothers with normal body weight, children of mothers with excess body weight or obesity showed a tendency toward higher body weight, as well as greater variability in body weight according to the 95% confidence interval of the mean value. In this case, the increase in infant body weight may be due to a combination of the influence of excessive maternal body weight or obesity during pregnancy [28], as well as favorable biochemical changes in breast milk resulting from these factors [29,30]. In the long term, this influence is combined with the environment in which the child grows; if this environment does not change, unhealthy eating habits and chronic physical inactivity persist, increasing the risk of a high BMI in both childhood and adulthood [28]. Regardless of the mechanism of influence on the infant, in the long term, excessive maternal body weight or obesity during pregnancy affects child development [31]. Women with a pre-pregnancy BMI ≥30 kg/m² were less likely to plan exclusive breastfeeding compared to women with normal and overweight. Also, women with BMI ≥25 kg/m² were less likely to plan breastfeeding for at least 12 months compared to women with lower BMI (P = 0.002). All women participating in the study planned breastfeeding and initiated breastfeeding. However, 6 months after delivery, it was found that an increase in maternal pre-pregnancy BMI was significantly associated with earlier cessation of lactation.

Conclusion. Based on the results of the reviewed literature sources, it has been established that excessive body weight and obesity during pregnancy are among the important risk factors that significantly affect the physical development of the fetus and newborn. High maternal BMI increases the likelihood of fetal growth disorders, the birth of a child with macrosomia or low birth weight. Such changes may affect the indicators of physical development of the child after birth, as well as increase the risk of developing metabolic diseases at a later age. In this regard, at the stage of pregnancy planning, it is important to control body weight in women, promote a healthy lifestyle, as well as ensure proper nutrition and medical supervision during pregnancy. This is an important preventive measure to ensure the healthy physical development of the fetus and the newborn child.

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