Managing Labor and Delivery of the Diabetic Mother

Hen Y. Sela, MD; Itamar Raz, MD; Uriel Elchalal, MD

Disclosures

Expert Rev of Obstet Gynecol. 2009;4(5):547-554. 

In This Article

Maternal & Fetal Complications Related to Labor & Delivery

Many fetal complications, such as intrauterine fetal death (IUFD), neonatal hypoglycemia, congenital anomalies, macrosomia and increased prenatal mortality, are related to DM.

Pregestational Diabetes

In pregnancies complicated by pre-GDM, the most important concerns during the third trimester are IUFD and both spontaneous preterm birth and early induction of labor owing to pregnancy complications that indicate premature delivery, such as preeclampsia (which is more prevalent in DM pregnant patients). The macrosomic newborn also carries an increased risk for both neonatal and maternal birth trauma.[3,4,10,17,18,19,20] In a recent study, it was found that women with pre-GDM were three-times more likely to have major maternal morbidity or mortality (7.9%; odds ratio [OR]: 3.2; 95% CI: 2.6-3.9) compared with women without DM (2.6%).[21] There was no statistically significant difference in the percentage of main maternal morbidity and mortality between mothers with Type 1 and Type 2 DM and unclassified types of pre-GDM. Major infant morbidity or mortality occurred in 13.6% of infants of mothers with pre-GDM compared with 3.1% for infants of mothers without DM (OR: 5.0; 95% CI: 4.2-5.8). Major infant morbidity and mortality was more frequent among infants of mothers with Type 1 DM (17.0%) compared with infants of mothers with Type 2 DM (11.5%) or infants of mothers with diabetes of unclassified Type (7.0%; p = 0.0001). Infants whose mothers had pre-GDM compared with infants of mothers without DM were 4.5-times more likely to be delivered before 37 weeks' gestation (19.5 vs 5.2%; OR: 4.5; 95% CI: 3.9-5.2) or to be macrosomic (35.0 vs 10.4%; OR: 4.6; 95% CI: 4.1-5.2).

In the Confidential Enquiry into Maternal and Child Health, it was found that:[3]

  • The prevalence of major congenital anomalies was 41.8 per 1000 births;

  • There was a threefold increase in anomalies of the circulatory system and neural tube defects;

  • Perinatal mortality was nearly four-times higher in babies born to women with diabetes than in the general maternity population.

Gestational Diabetes Mellitus

Among women diagnosed with GDM, one of the most commonly reported problems is fetal macrosomia.[22,23,24,25,26,27] Excessive fetal growth remains a significant perinatal concern in GDM. Maternal hyperglycemia continues to be viewed as the principal detectable determinant of increased fetal growth resulting from increased delivery of glucose to the fetus, which leads to fetal hyperinsulinemia.[28] Increased fetal growth is also influenced by increased maternal-fetal delivery of other nutrients, such as amino acids and lipids. Fetal growth in women with GDM is usually monitored antenatally by ultrasound. DM-related macrosomia is characterized by excessive increased growth of the fetal abdominal circumference (AC). The risk of macrosomia is most profound when GDM is not recognized, or detected when maternal compliance is suboptimal. Not every study uses the same criteria for macrosomia. Some authors use a cutoff value for birthweight of the 90th percentile at term,[27] some use birthweight of more than 4000 g and others use 4500 g as a cutoff for macrosomia.[29] The reported incidence of macrosomia (>4000 g) in women with GDM is 16-29%,[30,31] as opposed to a 10% rate in women without GDM. Macrosomic fetuses are at an increased risk of prolonged labor, operative vaginal delivery, asphyxia, Caesarean delivery and birth trauma, including shoulder dystocia and brachial plexus injury.[29,32]

The incidence of brachial plexus injury is greater with rising birthweight, operative vaginal delivery and the presence of glucose intolerance.[33] Brachial plexus injury is a severe complication, which may lead to permanent disability in 5-22% of newborns.[34]

There is an increased rate of Caesarean deliveries in GDM patients. However, this may be simply a tagging effect since, in a patient diagnosed with GDM, the threshold for Caesarean delivery by the obstetrician may be lowered. It has been reported that the incidence of Caesarean delivery rate is high in women with GDM (30%) compared with controls (20%), in spite of the fact that treatment of GDM normalized birthweights.[30] Limiting the criteria for Caesarean deliveries to maternal glycemic levels and ultrasound estimates of fetal weight may reduce the primary Caesarean section rate to that in the general population.[35]

Women with GDM were more likely to have major maternal morbidity and mortality (3.1%; OR: 1.2; 95% CI: 1.1-1.4) than women without DM (2.5%). Major infant morbidity or mortality occurs more often in infants of mothers with GDM (3.2%) compared with infants of mothers without DM (2.3%; OR: 1.4; 95% CI: 1.3-1.5).[21]

Gestational DM has been linked to an increase in hypertensive disorders, but there are several inconsistencies in this association and questions regarding whether it is causal in nature. One study found a 20% incidence of hypertensive disorders in GDM women compared with 11% in controls.[36] By contrast, in the Toronto Tri-Hospital Gestational Diabetes Project, only a 9% incidence of preeclampsia in untreated GDM was found,[30] which is comparable to the incidence reported in treated women with GDM and in women treated for Type 1 or Type 2 DM.[37] It appears more likely that any increase in hypertension in GDM patients could be explained by the fact that their BMI and age predispose them to both GDM and hypertension.

Neonates born to diabetic women are also at risk of hypoglycemia and other transient metabolic disorders. Although less frequent than in Type 1 DM, perinatal mortality may be increased with insulin-requiring GDM (GDMA2). In GDM, an increased rate of neonatal hypoglycemia, hypocalcemia, hyperbilirubinemia and polycythemia have been reported.[38] Postpartum neonatal hypoglycemia might occur when neonates are no longer exposed to high levels of maternal glucose. Neonates continue to produce high levels of insulin, but withdrawal of maternal glucose may lead to relative neonatal hyperinsulinemia and subsequent hypoglycemia.

Perinatal mortality (stillbirth and neonatal death in the first week postpartum) was originally regarded as the most important complication of GDM.

Estimates of perinatal mortality associated with GDM varied greatly over the past decades. A small study conducted 35 years ago demonstrated a fourfold increase in perinatal mortality among newborns of women with GDM.[39] Some 20 years later, in a prospective, interventional study of 2500 women with GDM, perinatal mortality rates were lower in GDM patients than in the control population.[40] Importantly, the presence of maternal fasting hyperglycemia (>105 mg/dl) may be associated with an increased risk of IUFD during the last 4-8 weeks of gestation.[41] To be able to draw a conclusion regarding the incidence of perinatal mortality, a much larger study is required.

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