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Management> Pregnancy>
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Pregnancy and Diabetes

Wanda Nicholson, M.D.
02-04-2011

DEFINITION

  • Diabetic pregnancy refers to both pre-gestational and gestational diabetes.
  • Pre-gestational diabetes: diabetes diagnosed before a woman conceives.
  • Gestational diabetes (GDM): diabetes diagnosed after the onset of pregnancy.

EPIDEMIOLOGY

  • Pre-gestational diabetes (including both type 1 and type 2) affects 1% of all pregnancies (Lawrence).
  • Epidemiology of GDM described elsewhere.
  • In type 1 diabetes, duration of diabetes significant predictor of caesearian delivery. Chronic hypertension associated with prematurity and perinatal mortality (Gonzalez).
  • In type 2 diabetes, higher A1c in first trimester significant predictor of congenital malformations and perinatal mortality; higher A1c in third trimester related to prematurity. Macrosomia associated with higher rates of caesearian delivery (Gonzalez).

DIAGNOSIS

CLINICAL TREATMENT

Glucose goals in diabetic pregnancy

  • Extremely "tight" blood glucose control is targetted during pregnancy, in order to minimize the risk of neonatal congenital abnormalities (related to glycemia in 1st trimester), fetal macrosomia (correlated to glycemia in last 2 trimesters), prematurity and perinatal mortality.
  • Targets shown in Table. Using self-monitoring, mean capillary glucose levels target 100 mg/dL. Goal hemoglobin A1C < 6%.
  • Check HbA1c monthly, although SMBG more useful for immediate care.
Evaluation and assessment of diabetic pregnancy

  • Check comprehensive metabolic panel, thyroid function tests, electrocardiogram after pregnancy confirmed; refer to ophthalmology if not evaluated in past year.
  • Assess baseline renal function with 24 hour protein and urine creatinine clearance. 
  • Ultrasound evaluations: early ultrasound for dating and estimated due date; anatomical ultrasound (18-22 weeks); and serial ultrasounds around 28-32 weeks and 34-36 weeks gestation to access fetal growth percentiles.
  • Fetal echo: at 18-22 weeks to assess fetal cardiac structure; at 34-36 weeks, ultrasound evaluation of the fetal cardiac interventricular septum may also be performed. An increase in size may indicate poor glucose control.
  • Fetal surveillance: beginning at 32 to 34 weeks gestation, should be conducted at appropriate intervals and can include a combination of fetal movement counting, nonstress test, contraction stress test and biophysical profile. Twice weekly fetal surveillance has been widely adopted beginning at 32 to 34 weeks gestation, but can be individualized.
  • Doppler velocimetry of the umbilical artery may be useful in monitoring pregnancies with poor fetal growth.
Dietary and pharmacologic management of glycemia in pregnancy

  • In GDM, dietary control may be adequate with appropriate carbohydrate restriction. A diet consisting of 40-50% carbohydrate is recommended. A nutritionist may help with calorie and carbohydrate counting; women with normal weight require up to 30-35 kcal/kg/day. Women with mild gestational diabetes (i.e. an abnormal result on an oral glucose-tolerance test but a fasting glucose level below 95 mg per deciliter [5.3 mmol per liter]) may do well on diet control alone.
  • Oral hypoglycemic agents, including glyburide (FDA category C) and metformin (FDA category B), can be used safely in GDM, but insulin is considered the primary therapy and preferred if hyperglycemia persists with diet alone.
  • Insulin can be delivered through subcutaneous administration or insulin pump (for type 1 diabetes).
  • Regular, lispro, aspart, NPH insulins are all FDA Category B; insulin glargine, detemir and glulisine are all FDA Category C. (See bolus insulin and basal insulin modules).
  • Administer short- or rapid-acting insulins (regular insulin, insulin lispro, and insulin aspart) before meals to reduce post-meal hyperglycemia.
  • Give regular insulin ~ 30 minutes before eating. Give lispro and aspart immediately before eating.
  • Lispro and aspart are very fast acting, so hypoglycemia can occur if food is not ingested shortly after their administration. Use caution especially if patient is vomiting frequently.
  • Long- and intermediate- acting insulins (NPH insulin, insulin glargine, detemir) are used once or twice daily.
  • Insulin requirements usually increase during pregnancy, especially during the third trimester, but decline soon after delivery; patients usually require lower insulin doses following childbirth and with breastfeeding.
  • Preferred insulin injection site is abdomen, with no evidence that it will harm the baby.
Management of delivery in diabetic pregnancy

  • Control maternal glucose during labor with intravenous regular insulin to keep glucose levels less than 120 mg/dl.
  • Delivery of pregnancies complicated by diabetes can occur safely at 39 weeks gestation.
  • Earlier delivery, particularly in pregnancies complicated by diabetic vascular changes, can occur but only after amniocentesis has been performed to confirm fetal lung maturity.
  • Although ultrasound is often used to assess fetal weight and rule out macrosomia before delivery, it has not proven to be more effective than clinician evaluation.
  • Cesarean delivery should be considered if the estimated fetal weight is greater than 4,500 g in women with diabetes.
  • Induction of labor in pregnancies for suspected macrosomia does not reduce birth trauma and may increase the risk of cesarean delivery.
Complications of Diabetic Pregnancy

  • Maternal complications during pregnancy may occur more frequently, but are similar to diabetic complications in non-pregnant women.
  • Diabetes increases the risk of cesarean delivery and postoperative complications.
  • Shoulder dystocia three times higher compared to non-diabetic pregnancy.
  • Risk of preeclampsia 13-14% higher during diabetic pregnancy.
  • Polyhydramnios more common in diabetic pregnancy.
  • Maternal hyperglycemia can lead to miscarriage or premature labor and delivery.
  • Maternal hyperglycemia can also lead to vascular disease including the development of hypertension, kidney disease, stroke and worsening diabetic retinopathy in the mother.
  • Maternal hyperglycemia contributes to poor or delayed fetal lung maturity in the infant.
  • Accelerated growth of the fetus with uncontrolled maternal hyperglycemia, leading to a large-for-gestational age infant. Macrosomia, defined as an infant > 4500 grams, occurs in up to 10% of diabetic pregnancies. Even mild hyperglycemia increases birth weight (Landon).
  • In the infant: neonatal hypoglycemia/seizures, hypocalcemia, hyperbilirubinemia, polycythemia occur more frequently; also increased risk of congenital abnormalities, perinatal mortality, and intrauterine growth retardation (with co-existing maternal vascular disease). 

Tables/Images

FOLLOW UP

EXPERT COMMENTS

  • Preconception care should include A1c as close to 7 as possible and evaluation for medications that are commonly used to treat diabetes and its complications, since they may be contraindicated during pregnancy, including statins, ACE inhibitors, ARBs, and most non-insulin diabetes therapies.
  • Diabetic retinopathy may progress during pregnancy and should be evaluated by an ophthalmologist before and during pregnancy.
  • Emerging evidence shows that a fetus exposed to maternal hyperglycemia during development undergoes alterations in metabolism ("fetal programming") which predispose the infant to childhood obesity and diabetes.

Basis for Recommendations

  • American Diabetes Association; Preconception care of women with diabetes.; Diabetes Care; 2004; Vol. 27 Suppl 1; pp. S76-8;
    ISSN: 0149-5992;
    PUBMED: 14693933
    Rating: Basis for recommendation
    Comments:Outlines the American Diabetes Association guidelines on preconception care in women with diabetes.

REFERENCES


 
 
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