Diabetes and pregnancy: Risks and opportunities
ABSTRACT
Diabetes in pregnancy increases the risk of adverse maternal, obstetric, fetal, and neonatal outcomes. Internists can reduce these risks by optimizing glycemic control before conception and providing effective counseling on strategies to reduce the risks associated with pregnancy and diabetes. Routine screening of reproductive-age women with diabetes should include a comprehensive physical examination and laboratory tests to identify at-risk patients and begin strategic management. A review of medications for teratogenic potential is also needed.
KEY POINTS
- Aim for a hemoglobin A1c of 6.5% or lower, if it is attainable without increasing the risk of hypoglycemia.
- Avoid teratogenic drugs in sexually active women of childbearing age unless the patient uses effective contraception.
- Because about half of pregnancies are unplanned, it is important to routinely discuss family planning and provide preconception counseling that includes reducing risks associated with pregnancy.
- Screen for diabetic end-organ damage, especially retinopathy and nephropathy.
IS BREASTFEEDING AFFECTED?
Maternal diabetes, insulin therapy, and oral hypoglycemic agents are not contraindications to breastfeeding. The US Preventive Services Task Force recommends interventions by primary care physicians to promote and support breastfeeding.45 Breastfeeding is encouraged based on various short- and long-term health benefits for both breastfed infants and breastfeeding mothers. Breastfeeding decreases a woman’s insulin requirements and increases the risk for hypoglycemia, especially in patients with insulin-dependent type 1 diabetes.1
Additionally, insulin sensitivity increases immediately following delivery of the placenta.1 Therefore, it is prudent to adjust insulin doses postpartum, especially while a patient is breastfeeding, or to suggest high-carbohydrate snacks before feeds.9,29
Antihypertensive drugs considered safe to use during lactation include captopril, enalapril, quinapril, labetalol, propranolol, nifedipine, and hydralazine.21,46 Methyldopa is not contraindicated, but it causes fatigue and worsened postpartum depression and should not be used as first-line therapy. Diuretics and ARBs are not recommended during lactation.21 Both metformin and glyburide enter breast milk in small enough amounts that they are not contraindicated during breastfeeding.16 The Lactmed database (www.toxnet.nlm.nih.gov) provides information about drugs and breastfeeding.
WHAT ABOUT CONTRACEPTIVES?
The ADA recommends contraception for women with diabetes because, just as in women without diabetes, the risks of unplanned pregnancy outweigh those of contraceptives.1
We recommend low-dose combination estrogen-progestin oral contraceptives to normotensive women under age 35 with diabetes but without underlying microvascular disease. For women over age 35 or for those with microvascular disease, additional options include intrauterine devices or progestin implants. We prefer not to use injectable depot medroxyprogesterone acetate because of its side effects of insulin resistance and weight gain.47
CASE DISCUSSION: NEXT STEPS
Our patient’s interest in family planning presents an opportunity for preconception counseling. We recommend a prenatal folic acid supplement, diet and regular exercise for weight loss, and screening tests including a comprehensive metabolic panel, hemoglobin A1c, thyroid-stimulating hormone, and dilated eye examination. We make sure she is up to date on her indicated health maintenance (eg, immunizations, disease screening), and we review her medications for potential teratogens. She denies any recreational drug use. Also, she has no plans for long-distance travel.
Our counseling includes discussions of pregnancy risks associated with pregestational diabetes and suboptimal glycemic control. We encourage her to use effective contraception until she is “medically optimized” for pregnancy—ie, until her hemoglobin A1c is lower than 6.5% and she has achieved a medically optimal weight. If feasible, a reduction of weight (7% or so) through lifestyle modification should be attempted, and if her hemoglobin A1c remains elevated, adding insulin would be recommended.
Pregnant patients or patients contemplating pregnancy are usually motivated to modify their behavior, making this a good time to reinforce lifestyle modifications. Many patients benefit from individualized counseling by a registered dietitian to help achieve the recommended weight and glycemic control.
Our physical examination in this patient includes screening for micro- and macrovascular complications of diabetes, and the test results are negative. Patients with active proliferative retinopathy should be referred to an ophthalmologist for assessment and treatment.
We review her medications for potential teratogenic effects and stop her ACE inhibitor (lisinopril) and statin (simvastatin). We switch her from a first-generation sulfonylurea (chlorpropamide) to glyburide, a second-generation sulfonylurea. Second-generation sulfonylureas are considered more “fetus-friendly” because first-generation sulfonylureas cross the placenta more easily and can cause fetal hyperinsulinemia, leading to macrosomia and neonatal hypoglycemia.7
The management of diabetes during pregnancy leans toward insulin use, given the lack of information regarding long-term outcomes with oral agents. If insulin is needed, it is best to initiate it before the patient conceives, and then to stop other diabetes medications. We would not make any changes to her aspirin or metformin use.
Educating the patient and her family about prevention, recognition, and treatment of hypoglycemia is important to prevent and manage the increased risk of hypoglycemia with insulin therapy and in early pregnancy.1 Consideration should be given to providing ketone strips as well as education on diabetic ketoacidosis prevention and detection.1 If the patient conceives, begin prenatal care early to allow adequate planning for care of her disease and evaluation of the fetus. Because of the complexity of insulin management in pregnancy, the ADA recommends referral, if possible, to a center offering team-based care, including an obstetrician specialized in high-risk pregnancies, an endocrinologist, and a dietitian.1
