Macrosomia and Its Maternal Causes

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Questions and Answers

What is identified as the most significant factor in the pathogenesis of fetal macrosomia?

Maternal nutrition

Fetal genetic factors

Maternal hyperglycemia (correct)

Maternal exercise levels

Which hormones are associated with the increase in maternal insulin resistance during the second trimester?

Cortisone, HPL, and prolactin (correct)

Oxytocin and relaxin

Testosterone and DHEA

Estrogen and progesterone

What relationship was shown by the Hyperglycemia and Adverse Pregnancy Outcomes study?

A linear relationship exists between maternal glucose and LGA fetuses. (correct)

Maternal glucose has no impact on fetal adiposity.

Higher maternal glucose correlates with smaller for gestational age fetuses.

Maternal glucose concentrations are inversely related to fetal growth.

What is the association of fasting blood glucose levels with macrosomia in women without diabetes?

Fasting glucose levels show a stronger association with macrosomia Signup and view all the answers

What risk increase is seen for macrosomia in women diagnosed with gestational diabetes mellitus (GDM)?

Two-fold to three-fold Signup and view all the answers

What percentage of women with GDM A1 had LGA newborns in the study mentioned?

29 percent Signup and view all the answers

What physiological response counteracts maternal insulin resistance during pregnancy?

Postprandial hyperinsulinemia Signup and view all the answers

Which group of women had the highest percentage of LGA newborns according to the research findings?

Women with preexisting diabetes Signup and view all the answers

What is the mechanism through which glucose transfer occurs from mother to fetus?

Facilitated diffusion Signup and view all the answers

How does maternal hyperglycemia affect the fetal pancreas?

Leads to hyperplasia of beta islet cells Signup and view all the answers

What weight gain is recommended for a pregnant patient with a BMI of 26?

7-11.5 kg Signup and view all the answers

Which of the following is NOT a recommended laboratory evaluation for maternal health during pregnancy?

Vitamin D levels Signup and view all the answers

Which statement accurately reflects a risk factor for macrosomic fetuses?

Diabetic mothers increase the risk of macrosomia. Signup and view all the answers

Which method is insufficient for diagnosing macrosomia on its own, according to ACOG guidelines?

Routine blood tests Signup and view all the answers

What electrolyte levels should be monitored immediately after the delivery of neonates born to diabetic mothers?

Glucose, calcium, and bilirubin levels Signup and view all the answers

Which maternal condition requires screening during the evaluation process?

Hyperglycemia Signup and view all the answers

Which complication is NOT commonly associated with macrosomic infants?

Low birth weight Signup and view all the answers

What is the first step in understanding a patient’s obstetric history?

Date of the last menstrual period (LMP) Signup and view all the answers

What medical condition is related to polyhydramnios in pregnant patients?

Gestational diabetes Signup and view all the answers

Which physical examination practice is crucial for monitoring pregnant patients?

Weight monitoring at each visit Signup and view all the answers

What is a significant maternal risk factor for fetal macrosomia among the following?

Poorly controlled diabetes Signup and view all the answers

Which term is generally associated with a birth weight that is at or above the 90th percentile for a given gestational age?

Large for gestational age (LGA) Signup and view all the answers

A prolonged gestation period greater than 42 weeks is associated with which outcome in pregnancy?

Higher likelihood of macrosomia Signup and view all the answers

Which genetic disorder has NOT been associated with macrosomia or large for gestational age fetuses?

Turner syndrome Signup and view all the answers

Which factor contributes to fetal macrosomia through maternal obesity?

4 to 12-fold increase in risk of macrosomia Signup and view all the answers

What is the historical definition weight of macrosomia regardless of gestational age?

4000 grams Signup and view all the answers

In terms of fetal gender, what significant difference is noted in relation to macrosomia?

Male fetuses tend to be 150 grams heavier than females. Signup and view all the answers

What percentage of infants exhibited a birth weight greater than 4000 grams in 2017?

7.8% Signup and view all the answers

What is a lesser-known maternal risk factor contributing to macrosomia?

Multiparity Signup and view all the answers

Which of the following does NOT affect the risk of macrosomia?

Environmental exposure Signup and view all the answers

What is the primary cause of postpartum hemorrhage (PPH) influencing maternal mortality?

Uterine atony Signup and view all the answers

Which of the following is NOT commonly associated with congenital anomalies in infants of diabetic mothers?

Hyperbilirubinemia Signup and view all the answers

What is the likely risk of developing shoulder dystocia in a newborn weighing 4200 g?

5-10% Signup and view all the answers

What complication is particularly linked to the prolonged second phase of labor?

Perineal trauma Signup and view all the answers

Which management strategy for pregnancies with macrosomia has been discouraged due to lack of clear evidence?

Induction of labor (IOL) Signup and view all the answers

What is the expected blood loss threshold defining postpartum hemorrhage after a vaginal delivery?

500 mL Signup and view all the answers

In cases of fetal macrosomia, what can help reduce the risk of perinatal complications?

Improved glycemic control Signup and view all the answers

Which condition occurs as a mechanical inability during birth, specifically after the delivery of the fetal head?

Shoulder dystocia Signup and view all the answers

Which of the following electrolyte imbalances is linked with newborns of diabetic mothers?

Hypocalcemia Signup and view all the answers

What is a common complication of macrosomic pregnancies that poses challenges to healthcare providers?

Appropriate treatment and intervention Signup and view all the answers

Study Notes

Macrosomia Definition

Macrosomia refers to excessive fetal growth, characterized by a birth weight equal to or greater than the 90th percentile for a given gestational age.
A universally accepted definition of macrosomia is challenging, often using an absolute birth weight threshold of 4,000g or 4,500g, regardless of gestational age.
"Large for gestational age" (LGA) is another term used for excessive fetal growth.

Etiology - Maternal Causes

Maternal Diabetes: Poorly controlled diabetes during pregnancy (including gestational, insulin-dependent, or drug-induced) significantly increases the risk of fetal macrosomia.
Obesity: Maternal obesity is linked to a 4-12 fold increased risk of fetal macrosomia. This is a significant global concern.
Multiparity: While not inherently a major risk factor, it can contribute to macrosomia due to an association with conditions like maternal diabetes and obesity.
Previous LGA Infants: Women who have delivered previous LGA infants are at a 5-10 fold increased risk for a subsequent LGA infant.
Post-date Pregnancy: Prolonged gestation (over 42 weeks) increases the risk of macrosomia.

Etiology - Fetal Causes

Fetal Gender: Male fetuses are typically 150 grams heavier than female fetuses overall, although not always.
Genetic and Congenital Disorders: Certain congenital disorders (e.g., Beckwith-Wiedemann syndrome, Sotos syndrome, Fragile X syndrome, Weaver syndrome) are associated with macrosomia and LGA fetuses.

Epidemiology

In 2017, approximately 7.8% of infants had a birth weight exceeding 4,000 grams, and 0.1% exceeded 5,000 grams.
Other factors like race, ethnicity, and genetics play a role in contributing to macrosomia.
Hispanic pregnant women are observed to be at a higher risk.

Pathophysiology

Pregnancy involves a complex interplay of physiological and endocrine changes to support fetal growth.
Maternal hyperglycemia is a key factor in macrosomia pathogenesis.
Increased maternal stress hormones (cortisone, human placental lactogen, prolactin) contribute to insulin resistance during pregnancy.
Maternal hyperglycemia results in fetal hyperglycemia and hyperplasia of fetal beta islet cells. This overstimulates glucose metabolism in the infant.
Glucose crosses the placenta through facilitated diffusion.

Associated with Macrosomia

Hyperglycemia in pregnant women is strongly associated with macrosomia.
In gestational diabetes mellitus (GDM) cases, even with treatment, the risk of macrosomia is 2-3 times greater.

History

Essential maternal history includes the first day of last menstrual period (LMP), gestational age, parity, pre-pregnancy weight.
Other information such as previous pregnancies (especially if with macrosomic infants) previous medical conditions, immunizations, and family history are particularly important.

Physical Examination

Patient weight should be correlated with standard guidelines based on pre-pregnancy BMI (e.g., 11.5 - 16 kg for BMI between 18.5 to 24.9.)
Specific weight gain recommendations are given according to pre-pregnancy BMI (for patients with low BMI weight gain should be 12 to 18kg).
Physical exam can exclude other possible conditions.

Maternal Evaluation

Maternal hyperglycemia screening is crucial.
Complete blood count (CBC), urinalysis, BUN, creatinine, and lipid profiles, liver function tests (LFTs), and blood pressure monitoring is important.
Routine fetal imaging studies (abdominal ultrasound) are important.

Fetal Evaluation

Macrosomic fetuses are at risk of various metabolic derangements, and frequent monitoring, lab work (glucose, calcium, magnesium, bilirubin, complete blood count) are essential.
Fetal glucose levels are assessed immediately after delivery and compared to baseline values.
Potential complications from polycythemia, hypocalcemia, or hypomagnesemia should be addressed.
Fetal condition should be carefully monitored given the risk of complications.

Complications - Maternal

Excessive blood loss (postpartum hemorrhage, PPH) is a major maternal complication.
Uterine atony and over-distention of the uterus contributes to this issue.
Perineal trauma due to prolonged labor and operative deliveries is also a risk.

Complications - Fetal

Shoulder dystocia, a difficulty birthing, can result in injury, and brachial plexus problems.
Congenital anomalies (heart problems, caudal regression syndrome, small left colon syndrome, spinal bifida,etc), and metabolic (such as electrolyte imbalances like hypocalcemia, hypomagnesemia, hyperinsulinemia, hypoglycemia) issues in the newborn are possible.
Fetal distress is another possible problem.
Polycythemia (high red blood cell count) and hyperbilirubinemia (high bilirubin level) can potentially occur.

Management

Induction of labor (IOL) is often discouraged due to a lack of clear evidence.
Improved glycemic control can reduce risk in pregnancies complicated with diabetes.
Pregnancies with macrosomia and no underlying diabetes require careful management, possibly electing a Cesarean delivery.
Assisted vaginal deliveries (forceps, vacuum) require significant caution.

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Description

This quiz explores the definition of macrosomia, characterized by excessive fetal growth, and examines its maternal causes, including diabetes and obesity. Understanding these factors can help in managing and preventing macrosomia during pregnancy.