Pregnancy In Diabetes Mellitus

• Close monitoring
• Tight control of blood glucose
• Management of complications

Preconception counseling and optimal control of diabetes before, during, and after pregnancy minimize maternal and fetal risks, including congenital malformations. Because malformations may develop before pregnancy is diagnosed, the need for constant, strict control of glucose levels is stressed to women who have diabetes and who are considering pregnancy (or who are not using contraception).

To minimize risks, clinicians should do all of the following:

• Involve a diabetes team (eg, physicians, nurses, nutritionists, social workers) and a pediatrician
• Promptly diagnose and treat complications of pregnancy, no matter how trivial
• Plan for delivery and have an experienced pediatrician present
• Ensure that neonatal intensive care is available
• In regional perinatal centers, specialists in management of diabetic complications are available

DURING PREGNANCY

Women with type 1 or 2 should monitor their blood glucose levels at home. During pregnancy, normal fasting blood glucose levels are about 76 mg/dL (4.2 mmol/L).

Goals of treatment are

• Fasting blood glucose levels at < 95 mg/dL (< 5.3 mmol/L)
• 2-hour postprandial levels at ≤ 120 mg/dL (≤ 6.6 mmol/L)
• No wide blood glucose fluctuations
• Glycosylated Hb (HbA1c) levels at < 6.5%

Insulin is the traditional drug of choice because it cannot cross the placenta and provides more predictable glucose control; it is used for types 1 and 2 diabetes and for some women with gestational diabetes. In some women with long-standing type 1 diabetes, hypoglycemia does not trigger the normal release of counterregulatory hormones (catecholamines, glucagon, cortisol, and growth hormone); thus, too much insulin can trigger hypoglycemic coma without premonitory symptoms. All pregnant women with type 1 should have glucagon kits and be instructed (as should family members) in giving glucagon if severe hypoglycemia (indicated by unconsciousness, confusion, or blood glucose levels < 40 mg/dL [< 2.2 mmol/L]) occurs.

Oral hypoglycemic drugs (eg, glyburide) are being increasingly used to manage diabetes in pregnant women because of the ease of administration (pills compared to injections), low cost, and single daily dosing. For women with type 2 diabetes before pregnancy, data for use of oral drugs during pregnancy are scant; insulin is most often preferred. Oral hypoglycemics taken during pregnancy may be continued postpartum during breastfeeding, but the infant should be closely monitored for signs of hypoglycemia.

Although diabetic retinopathy, nephropathy, and mild neuropathy are not contraindications to pregnancy, they require preconception counseling and close management before and during pregnancy.

Retinopathy requires that an ophthalmologic examination be done every trimester. If proliferative retinopathy is noted at the first prenatal visit, photocoagulation should be used as soon as possible to prevent progressive deterioration.

Nephropathy, particularly in women with renal transplants, predisposes to pregnancy-induced hypertension. Risk of preterm delivery is higher if maternal renal function is impaired or if transplantation was recent. Prognosis is best if delivery occurs ≥ 2 years after transplantation.

Congenital malformations of major organs are predicted by elevated HbA1c levels at conception and during the first 8 weeks of pregnancy. If the level is ≥ 8.5% during the 1st trimester, risk of congenital malformations is significantly increased, and targeted ultrasonography and fetal echocardiography are done during the 2nd trimester to check for malformations . If women with type 2 diabetes take oral hypoglycemic drugs during the 1st trimester, fetal risk of congenital malformations is unknown

Certain precautions are required to ensure an optimal outcome.

Timing of delivery depends on fetal well-being. Women are told to count fetal movements during a 60-minute period daily (fetal kick count) and to report any sudden decreases to the obstetrician immediately. Antenatal testing is begun at 32 weeks; it is done earlier if women have severe hypertension or a renal disorder or if fetal growth restriction is suspected.

Amniocentesis to assess fetal lung maturity may be necessary for women with the following:

• Obstetric complications in past pregnancies
• Inadequate prenatal care
• Uncertain delivery date
• Poor glucose control
• Poor adherence to therapy

Type of delivery is usually spontaneous vaginal delivery at term. Risk of stillbirth and shoulder dystocia increases near term. Thus, if labor does not begin spontaneously by 39 weeks, induction is often necessary; also, delivery may be induced between 37 to 39 weeks without amniocentesis if adherence to therapy is poor or if blood glucose is poorly controlled. Dysfunctional labor, fetopelvic disproportion, or risk of shoulder dystocia may make cesarean delivery necessary.

Blood glucose levels are best controlled during labor and delivery by a continuous low-dose insulin infusion. If induction is planned, women eat their usual diet the day before and take their usual insulin dose. On the morning of labor induction, breakfast and insulin are withheld, baseline fasting plasma glucose is measured, and an IV infusion of 5% dextrose in 0.45% saline solution is started at 125 mL/hour, using an infusion pump. Initial insulin infusion rate is determined by capillary glucose level

For spontaneous labor, the procedure is the same, except that if intermediate-acting insulin was taken in the previous 12 hours, the insulin dose is decreased. For women who have fever, infection, or other complications and for obese women who have type 2 and have required > 100 units of insulin/day before pregnancy, the insulin dose is increased.

After delivery, loss of the placenta, which synthesizes large amounts of insulin antagonist hormones throughout pregnancy, decreases the insulin requirement immediately. Thus, women with gestational diabetes and many of those with type 2 require no insulin postpartum. For women with type 1, insulin requirements decrease dramatically but then gradually increase after about 72 hours.

During the first 6 weeks postpartum, the goal is tight glucose control. Glucose levels are checked before meals and at bedtime. Breastfeeding is not contraindicated but may result in neonatal hypoglycemia if oral hypoglycemics are taken. Women who have had gestational diabetes should have a 2-hour oral glucose tolerance test with 75 g of glucose at 6 to 12 weeks postpartum to determine whether diabetes has resolved.