10.2 Maternal Medical Disorders in Pregnancy: Pregestational Diabetes, Epilepsy, Thrombocytopenia, Obesity & Cardiac Disease

Pregestational (Type 1 or Type 2) Diabetes

Risks

Hyperglycemia during organogenesis causes congenital anomalies (cardiac defects, neural tube defects, and caudal regression syndrome), with risk rising steadily with the A1C at conception. Later risks include miscarriage, preeclampsia, macrosomia and shoulder dystocia, polyhydramnios, stillbirth, and neonatal hypoglycemia, hyperbilirubinemia, and respiratory distress.

Care Before and During Pregnancy

• Preconception: A1C below 6.5% if achievable without hypoglycemia, folic acid, and a switch from teratogenic drugs (ACE inhibitors, ARBs, statins, GLP-1 receptor agonists).
• Baseline assessment: Dilated retinal exam (retinopathy can progress during pregnancy, so repeat as advised), serum creatinine and urine albumin-to-creatinine ratio, TSH (especially in type 1 diabetes), and ECG when cardiovascular risk is present.
• Aspirin 81 mg daily from 12–28 weeks for preeclampsia prevention.
• Glycemic targets match those for gestational diabetes: fasting <95 mg/dL, 1-hour postprandial <140 mg/dL, 2-hour <120 mg/dL. Insulin is preferred. Insulin needs often fall in the first trimester (hypoglycemia risk, especially in type 1) and rise steeply in the second and third trimesters as placental hormones increase insulin resistance. Continuous glucose monitoring is recommended in type 1 diabetes.
• DKA can develop at lower glucose levels in pregnancy and is dangerous for the fetus.
• Fetal evaluation: Early dating ultrasound, a detailed anatomy scan, fetal echocardiography (about 22 weeks), growth scans, and antenatal testing from about 32 weeks.
• Delivery timing (ACOG): 39 0/7–39 6/7 weeks if well controlled; 36 0/7–38 6/7 weeks with vascular complications, poor control, or prior stillbirth.
• Postpartum: Insulin requirements drop sharply after the placenta delivers, so reduce doses immediately to avoid hypoglycemia; breastfeeding further lowers glucose.

Epilepsy

• About one-third of patients have more seizures during pregnancy, often from falling drug levels, poor adherence driven by fear of teratogenicity, or sleep deprivation.
• Valproate carries the highest risk of malformations (neural tube defects and others) and lower child IQ and should be avoided when possible; lamotrigine and levetiracetam have the lowest malformation rates.
• Lamotrigine clearance rises by up to 200%–300% (estrogen-induced glucuronidation), and levetiracetam clearance also rises, so obtain a baseline level and check levels at least each trimester (often monthly) with dose adjustments. Reduce doses gradually after delivery to avoid toxicity.
• Folic acid at least 0.4 mg daily before and throughout pregnancy (AAN/AES/SMFM 2024); higher doses are common but not proven better.
• Breastfeeding is encouraged on most antiseizure drugs. Counsel safe infant-care practices, such as changing diapers on the floor and avoiding bathing the infant alone.
• A new seizure after 20 weeks is eclampsia until proven otherwise: give magnesium sulfate and evaluate.

Thrombocytopenia in Pregnancy

Treat ITP when platelets are below about 30,000/mcL, when there is bleeding, or before procedures, using corticosteroids or IVIG first-line. Many anesthesiologists accept neuraxial anesthesia at 70,000/mcL or higher (Society for Obstetric Anesthesia and Perinatology), and a count of about 50,000/mcL is generally adequate for cesarean birth.

Obesity (BMI 30 or Higher)

• Maternal risks: Gestational diabetes, preeclampsia, VTE, cesarean birth, wound infection, anesthetic complications, and postpartum hemorrhage.
• Fetal risks: Neural tube and cardiac anomalies, macrosomia, stillbirth, and reduced ultrasound visualization of anatomy.
• Care: Early diabetes screening, aspirin when obesity coexists with another moderate preeclampsia risk factor, a weight gain target of 11–20 lb, an anesthesia consultation for severe obesity, and mechanical plus pharmacologic VTE prophylaxis after cesarean as indicated.
• Antenatal testing (ACOG Committee Opinion 828): Weekly testing from 34 0/7 weeks for BMI ≥40 and from 37 0/7 weeks for BMI 35.0–39.9.
• After bariatric surgery: Delay pregnancy 12–18 months; monitor iron, B12, folate, vitamin D, and calcium; avoid the 50-g glucose challenge after Roux-en-Y gastric bypass (dumping syndrome) and use fingerstick monitoring instead; take abdominal pain seriously (internal hernia).

Cardiac Disease and Peripartum Cardiomyopathy

Cardiovascular conditions are a leading cause of pregnancy-related death. Normal pregnancy brings mild dyspnea, a systolic flow murmur, and dependent edema, but orthopnea, paroxysmal nocturnal dyspnea, chest pain, syncope, resting tachycardia, or oxygen saturation below 95% are red flags. Women with known heart disease are risk-stratified with the modified WHO classification and need cardio-obstetric care.

Peripartum cardiomyopathy: Heart failure with a left ventricular ejection fraction below 45% developing toward the end of pregnancy or in the months after delivery, with no other cause. Risk factors include Black race, preeclampsia or hypertension, multiple gestation, and older age. Evaluate with BNP and echocardiography. Treatment uses diuretics, beta-blockers, and hydralazine with nitrates during pregnancy (ACE inhibitors and ARBs only postpartum), plus anticoagulation for severely reduced function. Recurrence and mortality risks in a later pregnancy are high, especially if heart function has not recovered.