macrosomia
Introduction
Introduction to the huge fetus There is no uniform standard for the definition of extra large infants. In 1991, the American Obstetrics and Gynecology Association proposed that a newborn born with a birth weight of >4500g is a huge fetus, and 4000g is a huge fetus in China. A huge fetus is the result of a combination of factors, such as maternal diabetes, parental obesity, maternal, overdue pregnancy, polyhydramnios, ethnic and environmental factors. basic knowledge The proportion of illness: 0.08%, more common in pregnant women with diabetes Susceptible people: infants and young children Mode of infection: non-infectious Complications: uterine rupture Postpartum hemorrhage Neonatal asphyxia Meconium aspiration syndrome Scalp hematoma Intracranial hemorrhage Brachial plexus injury Fracture Neonatal hypoglycemia
Cause
Huge fetal cause
(1) Causes of the disease
A large fetus is the result of a combination of multiple factors, and it is difficult to explain it with a single factor. Clinical data show that only 40% of large fetuses have various high-risk factors, and the other 60% of large fetuses have no obvious high-risk factors, according to Williams. Description of obstetrics, common factors in large fetuses are diabetes, parental obesity, maternal, overdue pregnancy, maternal age, fetal sex, upper fetus, race and environment.
Diabetes in pregnant women (25%):
Whether it is pregnancy with diabetes or gestational diabetes, the incidence of huge fetuses is significantly increased. In the case of normal placental function, the blood glucose concentration of pregnant women with diabetes increases, resulting in increased fetal insulin secretion and high fetus. Glyceemia and hyperinsulinemia increase fetal anabolism, leading to an increase in the incidence of large fetuses, up to 20%, while the incidence of large fetuses in normal pregnant women is only 9%, but not all diabetes The incidence of large fetuses in pregnant women is increased. When the white grade of diabetes combined with pregnancy is above grade B, the placental function is reduced due to the hardening of the placental blood vessels, and the incidence of giant fetus is not increased, but the growth of the fetus is limited. The incidence is increasing.
Moreover, the shape of a huge fetus that occurs in pregnancy with diabetes is different from that of other large fetuses. Modanlou and McFarland found that the fetus's fat is accumulated in the shoulders and torso, especially by measuring the fetal diameter. The fetus is prone to shoulder dystocia, Bernstein et al. measured the thickness of subcutaneous fat in the subscapular and triceps, and found that the proportion of cesarean section in pregnant women with diabetes caused by neonatal obesity caused the cesarean section.
Obesity (20%):
Pregnant women are overweight, and obesity has adverse effects on pregnant women and newborns. First, obesity has an increased incidence of diabetes, chronic hypertension, etc. Calandra et al reported that when pregnant women gain more than the 95th percentile during pregnancy, they occur. The risk of obvious hypertension is 10 times that of normal pregnant women, about 17% is gestational diabetes. Secondly, obesity is another important factor independent of diabetes. The incidence of huge fetus in obese pregnant women is significantly increased, and in obesity. Among pregnant women with diabetes, the incidence of large fetuses is further increased. Johnson et al. compared pregnancy complications in 588 women weighing >113.4 kg (250 lbs) and 588 women weighing <90.7 kg (200 lbs). The incidence of diabetes, huge fetuses and shoulder dystocia is 10%, 24% and 5%, respectively, significantly higher than the latter's 0.7%, 7% and 0.6%. When the pregnant woman weighs >136kg (300 lbs), the huge fetus The incidence rate is as high as 40%. It can be seen that maternal obesity and gestational diabetes, large fetus and shoulder dystocia are closely related.
Expired pregnancy (18%):
There is a clear correlation with the huge fetus. The incidence of large fetuses in expired pregnancy is significantly greater than that of full-term pregnancies. According to Eden statistics in 1987, the birth weight of newborns with expired pregnancy is 120-180 g more than that of full-term children. The incidence is 7 times that of full-term children, and the incidence of shoulder dystocia is 2 times higher than that of full-term children. Moreover, with the increase of gestational age, the incidence of huge fetuses is increasing. Arias et al reported a huge 38- to 40-week pregnancy. The incidence rate of the fetus is 10.4%, the incidence rate is 41% in the 41st to 42th week of pregnancy, and 42.3% in the 43 to 44 weeks of pregnancy. Therefore, as long as the function of the placenta is good, the fetus grows continuously, and the longer the pregnancy, the greater the weight of the fetus. .
Too much amniotic fluid (10%):
Huge fetuses often coexist with polyhydramnios. The causal relationship between the two is still unclear. Chamberlain et al used B-ultrasound to detect the depth of the pond pool, and its vertical depth >8cm is too much amniotic fluid. In the case of 7096 cases with normal amniotic fluid volume, The incidence of huge fetuses was 8.7%, and the incidence of large fetuses in 43 cases of polyhydramnios was 33.3%. Benson et al. found that 17% of large fetuses had excessive amniotic fluid, while normal-weight fetuses combined with polyhydramnios Only 8%.
(two) pathogenesis
Genetic factor
There are a series of processes involved in the growth and development of the fetus, including: organ differentiation, weight gain, and improved body function. The cellular level of fetal growth (including cell growth, differentiation, and protein synthesis) has not yet been fully elucidated. Normally, singleton pregnancies After 36 weeks, fetal growth slows after 30 weeks of twin pregnancy. In early and mid-pregnancy, the weights of different fetuses are roughly similar. In late pregnancy, genetic factors and environmental factors (including maternal nutrition and placental factors) are common. The regulation of fetal growth and development, the study of single-oval twins showed that genetic factors have a greater impact on fetal weight, the two fetuses of single-oval twins have significant correlation, ethnic and fetal gender Genetic influence on fetal weight, in which full-term male infants weigh 150-200g more than female infants, mothers can affect fetal weight more genetically than fathers.
2. Hormone, growth factor
(1) Insulin: It is an important hormone regulating fetal growth and development. Because pregnant women cannot pass insulin through the placenta, fetal insulin is derived from the fetus. Injecting insulin into fetal monkeys and fetal rats can increase their body weight by 10% to 25%. Infusion of glucose with fetal rats can increase their body weight by 10% to 20%, but the use of insulin in fetal and fetal sheep has not been shown to increase their body weight. In humans, it has been reported that fetal islet dysplasia can lead to fetal growth restriction ( FGR), fetal growth retardation starts from 30 to 32 weeks of gestation. Resection of the pancreas can reduce the weight growth of the fetus by 40% to 50%. The use of insulin replacement therapy can make the growth of the fetus normal, regulated by insulin in pregnant women, pregnant women. The blood sugar level is in a narrow range of variation, so the blood glucose level in the fetus is relatively stable through the placenta. Although the insulin can be detected in the fetus in the 8 to 10 weeks of pregnancy, the insulin in the fetus does not affect the blood glucose until 20 weeks of gestation. Changes play a regulatory role, the regulation of insulin in the fetal body on blood sugar is affected by fetal blood glucose levels, chronic fetal hyperglycemia can increase fetal secretion of insulin Sensitivity and fetal pancreatic cells, the study of fetal display the insulin receptor, 19 to 25 weeks gestation, fetal tissue insulin receptor highest level, then, fetal tissue affinity to insulin is further improved.
(2) Insulin-like growth factor (IGF): present in the placenta and fetus, more research IGF including IGF-1 and IGF-2, IGF-1 can promote nutrients through the placenta to reach the fetus, and promote fetal growth and development, When the mother is starving, the level of fetal IGF-1 is decreased. Infusion of glucose or insulin to the fetus can restore IGF-1 to normal. Infusion of IGF-1 into the fetus during late pregnancy can increase the head and hip diameter of the fetus and promote the growth of its organs. And development, IGF-2 can affect placental growth, IGF-2 affects fetal growth and development by affecting the placenta, and IGF-2 gene-deficient nude mice have both placental growth retardation and fetal growth restriction.
Insulin-like growth factor binding protein (IGFBP) and other growth inhibitory factors regulate fetal growth and development by combating IGF. At least six IGFBPs have been identified to date. These IGFBPs bind to IGF-1, IGF-2 and insulin to regulate fetal growth. And development, in which IGFBP-3 binds 80% of IGF, the remaining IGFBP binds about 19% of IGF, and less than 1% of IGF is in a free state. High affinity with IGF has been detected from multiple tissues in humans. Cell surface receptors, in which the structure of the IGF receptor is similar to that of the insulin receptor, which binds to IGF-1, IGF-2 and insulin, and the IGF-2 receptor has a high affinity for IGF-2.
(3) Leptin: It plays a certain role in regulating the weight of pregnant women and fetuses. Shaarawy (1999) found that serum leptin levels in pregnant women are related to maternal obesity and greater than gestational age. Gao Yun et al (2000) proved cord blood. Leptin levels are positively correlated with fetal weight.
(4) Other hormones: Growth hormone plays an important role in the growth and development of the baby after birth, but it has little effect on the growth and development of the fetus before the birth of the fetus. For example, the growth hormone level of the non-brain fetus is reduced by 80% compared with normal. However, the weight of the diseased fetus was not significantly reduced. In animal studies, removal of the pituitary gland or breakage of the animal did not affect fetal growth rate.
Thyroxine has little effect on fetal growth regulation. The fetus of thyroxin is observed. Although its thyroxine production is increased, it has not found an increase in fetal growth rate. It even found suspicious fetal growth restriction. Adrenal cortical hormone matures to the fetus. The process (especially lung and intestine maturation) plays an important role.
3. Environmental factors
Malnutrition in pregnant women can affect fetal growth and development. Chronic disease in pregnant women can affect fetal growth restriction. Some metabolic abnormalities or toxins (such as pregnant women with phenylketonuria, Graves disease, alcoholism, etc.) can also affect fetal growth. Access to proper nutrition allows the full potential of fetal genetic students to be fully utilized.
Prevention
Huge fetal prevention
1. Diabetes screening
Because of the close relationship between giant children and gestational diabetes, it is necessary to screen all pregnant women for diabetes at 24 to 28 weeks of gestation. The pregnant women with diagnosed gestational diabetes and impaired glucose tolerance should be treated promptly and correctly.
2. Pregnant women nutrition guidance
Japan attaches great importance to the perinatal health care of pregnant women. Through nutrition counseling and guidance for pregnant women, it carries out pregnancy health exercises and appropriate physical activities, and the incidence of huge fetuses shows a downward trend.
Shen Yanhui et al (2000) showed that if the weight gain during pregnancy, high body weight, ideal body weight and low body weight during pregnancy were controlled at 3 to 9 kg, 9 to 15 kg, and 12 to 18 kg, the incidence of huge fetuses could be significantly reduced.
Complication
Huge fetal complications Complications uterine rupture postpartum hemorrhage neonatal asphyxia meconium aspiration syndrome scalp hematoma intracranial hemorrhage brachial plexus nerve injury fracture neonatal hypoglycemia
Difficulties in childbirth are the main complications of a large fetus. Due to the increase in fetal volume, the fetal head and shoulder are the main parts of labor difficulties. Due to the obvious increase in difficult labor, a series of complications of mother and child are brought about.
1. The head basin is not called
Due to the large fetal head of the large fetus, the pelvis of the pregnant woman is relatively narrow, the incidence of the head basin is not increased, and the double head diameter of the fetal head is larger, until the fetal head is not in the basin after delivery, if the fetal head is placed on Above the entrance level of the pelvis, it is called cyclism cross-positive, which shows that the first stage of labor is prolonged; if the double-diameter diameter is relatively smaller than the chest-abdominal diameter, the fetal head decline is blocked, and the second stage of labor is prone to prolongation, which may lead to secondary palace due to prolonged labor. At the same time, the large uterus has a large uterus volume, the uterine muscle fiber has a high tension, and the muscle fiber is excessively pulled, which is prone to primary uterine atony. The uterine weakness is in turn leading to abnormal fetal position, prolonged labor, and postpartum contractions. Weakness, soft birth canal laceration, postpartum hemorrhage and other complications increase, due to increased difficulty in yield, the incidence of cesarean section and vaginal surgery (pliers, aspirator) increased, in the backward areas, if not treated in time, uterine rupture can occur In the city, the cesarean section rate of a huge fetus can be increased by preventing dystocia.
2. Shoulder dystocia
The vaginal delivery of huge fetuses, the incidence of shoulder dystocia increased, especially the huge fetus of diabetes, Rouse et al reported that non-diabetic newborns born with birth weight <4000g, the incidence of shoulder dystocia is less than 1%, birth weight is 4000g Above, below 4500g, the incidence of shoulder dystocia is about 7%; birth weight > 4500g, the incidence of shoulder dystocia is 15%, but in gestational diabetes patients, the incidence of shoulder dystocia in the three groups is 1.2%, 14% and 50%.
If the shoulder dystocia is not handled properly, or the time is delayed, serious complications can occur, even life-threatening, such as neonatal asphyxia, meconium aspiration syndrome and various birth injuries. Head injuries can have scalp hematoma, intracranial hemorrhage, facial nerve spasm Brachial plexus injury, clavicular fracture, humeral fracture, etc., even sacral nerve injury.
3. Neonatal diseases
Because patients with gestational diabetes are prone to large fetuses, complications of fetal or neonatal diabetes can occur in large fetuses.
Pregnancy diabetes or pregnancy in pregnant women with diabetes due to long-term hyperglycemic environment, the secretion function of the pancreas is hyperthyroidism, if the energy is not replenished after delivery, the newborn is prone to hypoglycemia, severely endanger the life of the newborn or irreversible brain Injury, because high concentration of insulin can reduce the concentration of 3-phosphoglycerol and dioxyacetone, thereby inhibiting the synthesis of phospholipids, prone to neonatal respiratory distress syndrome, in addition, hypocalcemia, hyperbilirubinemia, erythrocytosis Incidence and other morbidity increase in large fetuses.
Symptom
Huge fetal symptoms Common symptoms Abdominal pain uterus enlargement is obvious (... Pregnant women non-pregnancy abdominal pain hidden postpartum hemorrhage
China has a huge fetus with 4000g. So far, there is no method for accurately estimating fetal weight in the uterus. Most giants are diagnosed after birth. The commonly used methods for predicting fetal weight are clinical measurement and ultrasound measurement. Clinical prediction of fetal weight:
Pregnant woman estimate
According to the uterus size of this and last pregnancy, pregnant women with childbirth experience can often estimate the fetal weight of this pregnancy more accurately. Chauhan et al (1994) studied the estimation of pregnant women, clinical estimates and results of ultrasound estimation of fetal weight, found that three The accuracy of fetal weight (within 10% error) was estimated to be 70%, 66% and 42%, respectively.
2. Clinical estimates
Comparing the clinical estimates and the accuracy of ultrasound estimation of fetal weight, the accuracy of estimating fetal weight was 67% and 66%, respectively. The average error of clinical estimation and ultrasound estimation of fetal weight were 296g and 194g, respectively, clinical estimation and ultrasound estimation. The mean error rates of fetal weight were 10.1% and 9.3%, respectively. Comparing clinical estimates and ultrasound estimates of fetal weight to or above 4000g accuracy, the estimated fetal weight accuracy was 58% and 51%, respectively, clinical estimates and ultrasound. The mean errors in fetal weight were estimated to be 245 g and 500 g, respectively. The mean error rates for clinical estimates and ultrasound estimates of fetal weight were 9.4% and 11.7%, respectively.
Examine
Inspection of a huge fetus
1. Blood sugar is increased, and huge fetuses are more common in diabetic patients.
2. Glycated hemoglobin is increased.
B-ultrasound can confirm a huge fetus.
Diagnosis
Huge fetal diagnosis
Diagnostic criteria
The current method can not accurately predict the huge fetus before birth. The diagnosis of a huge fetus can only be diagnosed according to the birth weight. Since there is no ideal method to date, the clinical weight and fetal ultrasound measurement are mainly used to estimate the fetal weight. There are many clinical indicators and calculation methods, but the accuracy is not satisfactory.
Clinical measurement
The height of the uterus and the abdominal circumference are indicators of routine clinical testing. Because of the simple method, it is widely used in clinical practice.
According to Gonggao and abdominal circumference, there are many formulas for calculating the birth weight of newborns, but the accuracy is not ideal. It can be used for initial diagnosis. According to the height of the uterus, the abdominal circumference is calculated, the birth weight of the newborn is diagnosed, and the huge fetus is diagnosed. The error is affected by factors such as the degree of obesity, height, and amniotic fluid of pregnant women. Here, only a simple calculation method is given.
Zeng Zhi et al. calculated the fetal weight according to Gonggao and abdominal circumference.
Formula 1: Fetal weight = (Qing Gao - n) × 150
When the fetus is first exposed below the plane of the ischial spine, n=11; when the fetus is first exposed to 0 to -1, n=12; when the fetus is first exposed to -2 or more, n=13.
Formula 2: Fetal weight = Gong Gao × abdominal circumference +150
The results of 168 cases showed that the proportions of the estimated body weights of formulas (1) and (2) within 100 g were 63% and 51%, respectively.
The formula proposed by Yuan Dongsheng et al. is as follows:
Formula 3: Fetal weight = Gong Gao × abdominal circumference +200
Formula 4: Fetal weight = Gong Gao × width of the uterus × 4.5
In 1996, Luo Lamin and others applied two steps to judge the huge fetus. The first step was to calculate the product of the height of the palace and the abdominal circumference. When the palace was high × abdominal circumference > 3700, the following regression formula was used to calculate the fetal weight:
Formula 5: Fetal weight = 2900 + Gong Gao × abdominal circumference
According to the formula, the coincidence rate of the huge fetus is 78%, and the standard deviation is 250g, which is higher than other indicators.
2. Ultrasound measurement
Many scholars estimate the birth weight of newborns based on the fetal diameter of the ultrasound examination. The commonly used diameters are fetal biparietal diameter (BPD) or fetal head circumference (HC), breast diameter (TD) or chest circumference (TC), and abdominal diameter ( AD) or abdominal circumference (AC), femur length (FL), etc., the calculation of fetal weight is many, but the accuracy is about 10%, especially when the fetus is too large or too small, the prediction error is greater, the earliest use The ultrasound index for predicting fetal weight is BPD. Zhuo Jingru (1980) examined the double-diameter diameter of 374 pregnant women. When the BDP was 10cm, the birth weight of the newborn was 3925g±323g, and at 10.2cm, it was 4000g, 10.4cm. 4290g, Luo Lamin et al reported that 90% of the double top diameter >10cm is a huge fetus. Therefore, the fetal double top diameter of ultrasound examination has great reference value in predicting huge fetus. AC and FL also play a role in predicting fetal weight. A very important role, AC may be a relatively accurate indicator of predicting large fetuses in a single indicator. Menon (1990) and Keller (1990) systematically monitor fetal AC in the 20th week of gestation. If the number of AC increases is greater than the average, The incidence of huge fetuses is elevated, FL is the development of fetal long bones Index, FL and fetal linear correlation hip top diameter, has a unique role in the predicted fetal weight, in conjunction with other indicators to improve prediction accuracy.
With the development and popularization of computer technology, the formula for predicting fetal weight is more and more complicated. The basic point of predicting fetal weight when using multiple ultrasound examination indexes is combined. The joint prediction formula proposed early and widely spread is the use of BPD by Shephard et al in 1982. And AC predicts the birth weight formula of newborns:
Equation 6: log10(BW)=-1.7492+0.166×BPD+0.046×AC-2.646×AC×BPD/1000
The birth weight of newborns in BW, the unit is g, log10 is the logarithm of base 10, and the unit of BPD and AC is centimeters (cm). Therefore, Hadlock proposes the calculation formula for predicting fetal weight using TC, AC and FL:
Equation 7: log10(BW)=1.5662-0.0108(TC)+0.0468(AC)+0.171(FL)+0.00034(TD)2-0.003685(AC×FL)
In the formula, the unit of BW is gram (g), and the unit of TC, AC and FL is centimeter (cm). Most formulas for predicting fetal weight are obtained by statistical multiple regression, when predicting the weight of a large fetus. The deviations are large, and there are many other calculation methods. DuBose et al. proposed the method of calculating the volume of the fetus. Li Xiaotian of Fudan University Obstetrics and Gynecology Hospital used artificial neural network to predict fetal weight.
According to the literature reports of the past 10 years, the sensitivity of the giant fetus is predicted to be only 60% and the specificity is 90%. In 1996, Adashek et al. believed that the fetal weight was predicted according to the current method. When the predicted value was >4000g, regardless of the newborn Whether the huge fetus, the rate of cesarean section is significantly increased, therefore, the advantages of the current method of predicting fetal weight based on the fetal diameter of the ultrasound examination have not been proven, but the data of ultrasound examination can provide reference for clinical obstetricians, clinical diagnosis The huge fetus should be diagnosed according to clinical history, abdominal examination, fundus height and abdominal circumference, as well as fetal measurement of fetal diameter, comprehensive analysis, combined with clinical experience to diagnose huge fetuses.
Differential diagnosis
Mainly differentiated from expired pregnancy and polyhydramnios, identification points:
1. According to whether the medical history is an expired pregnancy.
2. B-ultrasound difference between huge fetuses and polyhydramnios.
