Macrosomia PDF

Macrosomia Asena Ayar Madenli, M.D., Asst. Prof Istinye University Faculty of Medicine Department of Obstetrics and Gynecology definition According to the American College of Obstetrics and Gynecology (ACOG), two terms are applied to excessive fetal growth: “large for gestational age” (LGA) a...

Macrosomia Asena Ayar Madenli, M.D., Asst. Prof Istinye University Faculty of Medicine Department of Obstetrics and Gynecology definition According to the American College of Obstetrics and Gynecology (ACOG), two terms are applied to excessive fetal growth: “large for gestational age” (LGA) and “macrosomia.” Large for gestational age generally implies a birth weight equal to or more than the 90th percentile for a given gestational age. The term “macrosomia” implies growth beyond an absolute birth weight, historically 4,000 g or 4,500 g, regardless of the gestational age establishing a universally accepted definition for macrosomia is challenging  Etiology Maternal Causes 1. Maternal diabetes: poor controlled diabetes in pregnancy could be gestational diabetes, insulin-dependent, or drug-induced/chemical diabetes. 2. Obesity: globally, there is a current epidemic of obesity. Obesity constitutes a significant risk for diabetes mellitus in all demographics. Precisely, maternal obesity is linked to a 4 to 12 folds increase in the prospect of fetal macrosomia. 3. Multiparity: when compared to other maternal risk factors, multiparity is not a major risk factor for macrosomia. Still, it can contribute to maternal diabetes mellitus and obesity, which are more important causes.. 4. Previous LGA (large for gestational age) infants: women who have had previous macrocosmic babies are 5-10 folds at an increased risk 5. Post date pregnancy: prolonged gestation of more than 42 weeks is more likely linked with an increased chance of macrosomia due to the continuous supply of nutrients and oxygen-rich blood to the developing fetus. Etiology Fetal Causes 1. Fetal gender: macrosomia is more commonly observed in the male gender over the female gender. This can be partly attributed to the fact that male fetuses are usually about 150 grams heavier than female fetuses. 2. Genetic and congenital disorders: a couple of congenital disorders that have been shown to have associations with macrosomia and LGA fetuses are:  Beckwith – Weiderman syndrome  Sotos syndrome  Fragile X syndrome  Weaver syndrome Epidemiology report of the year 2017 indicates that %7.8 of infants had a birth weight greater than 4000 grams, while %1 had a birth weight greater than 4500 grams %0.1 5000grs. Other factors, such as age, race, genetics, ethnic groups are noted to also contribute to macrosomia. Hispanic pregnant women are observed to have a higher risk of fetal macrosomia compared to other races. Pathophysiology An interplay of physiologic and endocrine changes occurs in pregnancy, aiming at adequate nurturing of the developing fetus. The primary underlying pathophysiology of macrosomia could be broadly divided into maternal and fetal risk factors. However, maternal hyperglycemia appears to be the most significant factor in the pathogenesis of macrosomia. In the second trimester of pregnancy, an increase in the levels of the stress hormones such as cortisone, human placenta lactogen (HPL), and prolactin leads to modest degrees of maternal insulin resistance. This, however, is countered by physiologic postprandial hyperinsulinemia. Patients with metabolic syndrome or other existing risk factors may be unable to mount an adequate hyperinsulinemic response leading to the development of hyperglycemia. Glucose transfer through the placenta occurs through facilitated diffusion that results in fetal hyperglycemia. This, in turn, brings about the hyperplasia of the beta islet cells of the fetal pancreas leading to overutilization of glucose by the fetus and hence an abnormal increase in fetal growth. Pathophysiology Hyperglycemia and Adverse Pregnancy Outcomes study showed a strong linear relationship between maternal glucose concentration and large for gestational age (LGA) fetuses, fetal adiposity, and fetal hyperinsulinemia. A subsequent meta-analysis of the relationship between macrosomia (weight more than 4,000 g) and maternal glucose levels in women without diabetes demonstrates that a fasting blood glucose level or any abnormal value on oral glucose tolerance testing is associated with macrosomia. However, the fasting glucose level is more strongly associated with macrosomia. In women with GDM, the risk of macrosomia increases two-fold to three-fold, even with treatment. In a cohort of nearly 13,000 women, LGA newborns occurred in 29 percent of women with GDM A1, 30 percent of women with GDM A2, and 38 percent of women with preexisting diabetes.. (Type A1 GDM: Patients typically have an abnormal glucose tolerance test but can keep blood glucose levels in the normal range with dietary changes alone. Type A2 GDM: Patients usually have an abnormal glucose tolerance test and abnormal glucose levels during fasting and after meals and edication needed.) History  The first day of the last menstrual period (LMP)  Gestational age  Parity  Prepregnancy weight  Immunization history  Previous/existing medical conditions including diabetes mellitus, obesity, polyhydramnios, RH incompatibility  Past pregnancies, including previous macrosomic infants’ mode of delivery, associated complications, child gender Physical Examination Detailed physical examination should include monitoring of patient weight at each prenatal visit that should be correlated with suggested guidelines:  A weight gain of (12-18 kg) for patients with BMI of less than 18  A weight gain of (11.5-16 kg) for patients with BMI between 18.5to24.9  A weight gain of (7-11.5 kg) for patients with BMI between 25.0 to 29.9  A weight gain of (5-9 kg) for patients with BMI greater than 30 According to ACOG no singular modality such as Leupold maneuver, fundal height measurement, or an ultrasound scan can effectively diagnose macrosomia Evaluation Maternal Evaluation  Maternal hyperglycemia should be screened  Blood pressure monitoring to rule out pre-eclampsia  Complete blood count (CBC)  Urinalysis  BUN  Creatinine  Lipid profile  Liver function tests (LFT)  Routine fetal imagine studies with abdominal ultrasound Fetal Evaluation Macrosomic fetuses are at risk of various metabolic derangements and should be monitored closely. Laboratory measurements of the following electrolytes should be taken immediately after delivery.  Glucose levels: with the sudden withdrawal of the glucose-rich in utero environment, neonates born to diabetic mothers are prone to hypoglycemia.  Calcium levels: hypocalcemia and tetany can occur.  Magnesium levels: hypomagnesemia can also occur  Bilirubin levels: this may occur as a result of inefficient enterohepatic circulation and increased hemolysis if polycythemia also exists.  Complete blood count: it is necessary to check for polycythemia. Clinical evaluation of the neonate’s respiratory effort after birth is also essential as meconium aspiration due to fetal distress and transient tachypnea of the newborn (TTN) are common and tend to occur two to three times more frequently in macrocosmic babies, especially if secondary to gestational diabetes. Complications Maternal Postpartum hemorrhage (PPH): postpartum hemorrhage typically refers to excessive blood loss (greater than 500 mL) with vaginal delivery or loss of 1000 mL of blood or greater with the cesarian section. PPH is the leading cause of maternal mortality worldwide as well as in industrialized nations; it is one of the top three causes of maternal mortality. One of the most significant contributors to postpartum hemorrhage is uterine atony, which arises from the over-distention of the pregnant uterus and can be further complicated by macrosomic pregnancies. Perineal trauma : this arises from the prolongation of the second phase of labor and operative vaginal deliveries, both of which are associated with the delivery of macrosomic babies. Prolongation of the second phase of labor Complications Fetal  Shoulder dystocia: this refers to the mechanical inability to deliver the anterior fetal shoulder after delivery of the fetal head and is also associated with injury to the clavicle and brachial plexus. The occurrence of shoulder dystocia after vaginal deliveries varies with the weight of the newborn. There is a %1chance of shoulder dystocia in newborns with birth weight less than 4000 g and about a %5-10 chance for the newborn with a birth weight of 4000 to 4500 grams, %14 above 4500gr  Fetal distress  Congenital anomalies: most of which are associated with infants of diabetic mother includes congenital heart diseases, caudal regression syndrome, small left colon syndrome, spinal bifida, etc.  Metabolic and electrolyte imbalance, e.g., hypocalcemia, hypomagnesemia, hyperinsulinemia, hypoglycemia  Polycythemia  Hyperbilirubinemia Management Induction of labor (IOL), which was widely recommended until recently, has been discouraged due to the lack of clear evidence on its significance in the management of macrosomia. Pregnancies complicated by fetal macrosomia in patients with pre-existing or gestational diabetes and improved glycemic control via recommended pharmacologic and other interventions will lead to a reduction in the risk of perinatal complications. Pregnancies with macrosomia and no underlying diabetes pose a different challenge to the obstetric provider and other health care providers when appropriate treatment and intervention are needed. The American College of Obstetrics and Gynecology (ACOG) recommends an elective caesarian delivery to women with pregnancies complicated by macrosomia if the estimated fetal weight is above 5000 g and no underlying glucose intolerance or 4500 g with underlying glucose intolerance. Assisted vaginal delivery, such as forceps or vacuum-assisted deliveries, should be performed with significant caution in women with macrosomic pregnancies.