I. What is a giant baby? A giant baby is a fetus that grows beyond a specific threshold, regardless of gestational age. The most commonly used threshold is a weight over 4500 g. The current domestic definition is over 4000 g. A grading system has been proposed: grade 1 refers to infants weighing 4000-4499 g, grade 2 is 4500-4999 g, and grade 3 is over 5000 g. What are the risk factors for a giant baby? 1. physical factors, such as family traits, male gender, and Caucasian race; 2. environmental factors, such as maternal diabetes, weight gain during pregnancy, maternal obesity, overdue pregnancy, transitional delivery, and large placenta in early pregnancy; 3. heritable genetic variants, such as certain genetic syndromes, such as Beckwith-Wiedemann syndrome, which can cause excessive fetal growth Huge babies are usually associated with autochthonous factors, maternal diabetes (during pregnancy or pre-pregnancy) and/or maternal obesity/excessive weight gain during pregnancy. Due to the increasing prevalence of maternal overweight and obesity, maternal obesity and weight gain during pregnancy now have a greater impact on the incidence of macrosomia than maternal diabetes. A retrospective study examining the relative effects of pre-pregnancy weight and gestational diabetes on the incidence of larger-than-gestational-age infants showed that the incidence of larger-than-gestational-age infants was 7.7% and 12.7% in normal-weight and obese women without gestational diabetes, respectively. In contrast, the incidence of larger-than-gestational-age children was 13.6% and 22.3% in normal-weight and obese women with gestational diabetes, respectively, and these differences were statistically significant. That is to say, maternal obesity is the main influencing factor of huge children. Why does a giant baby appear? 1.At present, it is thought that an important way to appear a huge baby is intermittent maternal hyperglycemia and consequently fetal hyperglycemia. The release of insulin, insulin-like growth factor and growth hormone from the fetus can cause increased fetal fat deposition, thus causing weight gain. 2, Abnormal maternal lipid levels may also be an important factor. Although the association between maternal metabolic disorders (e.g., diabetes) and the emergence of larger-than-gestational-age infants is well established, macronutrient metabolism cannot fully explain this phenomenon because lifestyle changes (e.g., changes in the macronutrient composition of the maternal diet) do not have a reducing effect on the incidence of either. 3. Other maternal and placental factors can also influence the nutrient supply to the fetus and contribute to fetal overgrowth, including physical activity, uteroplacental blood flow, placental size, transplacental concentration gradient, and placental transit capacity. Such factors may be particularly important in pregnant women without diabetes mellitus. 4. syndromes associated with macrosomia If physical factors, maternal diabetes mellitus and/or maternal obesity/excessive weight gain during pregnancy have been ruled out or are highly unlikely, the presence of some rare syndrome associated with accelerated fetal growth should be considered, especially if 1 or more fetal structural abnormalities are present. There are many genetic disorders associated with fetal overgrowth. Therefore, consultation with a geneticist will be useful for differential diagnosis, prenatal diagnostic evaluation (e.g., selection of molecular tests and interpretation of results), and patient counseling. Important syndromes associated with fetal overgrowth: Pallister-Killian syndrome, Beckwith-Wiedemann syndrome, Sotos syndrome, Perlman syndrome, Simpson-Golabi-Behmel syndrome, Costello syndrome, Weaver syndrome, congenital Macrocephaly-Cutismarmoratatelangiectasiacongenita (M-CMTC) syndrome. Fourth, how to prevent the occurrence of huge children? 1. For women with diabetes, avoiding hyperglycemia has been shown to reduce the incidence of macrosomia. In 2 large randomized trials, treatment of gestational diabetes reduced the incidence of macrosomia by 50-60% (from 21% to 10% [152] and from 14.3% to 5.9%). It was found that in pregnant women with combined diabetic pregnancies, the average blood glucose level needs to be below approximately 100 mg/dL (5.6 mmol/L) to achieve a rate of macrosomia comparable to that of the non-diabetic pregnancy population. 2. Weight loss in obese women before pregnancy can reduce the risk of giving birth to a giant baby. Pre-pregnancy intervention is important because significant weight loss during pregnancy is likely to be unsafe, and sometimes accelerated fetal growth can occur as early as early or early to mid-term pregnancy. 3. For women of normal weight, avoiding excessive weight gain during pregnancy may reduce the risk of a large baby.