Diabetes and pregnancy

Did You Know?

• The placenta produces human placental lactogen (HPL), a hormone with counter-regulatory actions that increase blood glucose levels.
• Consequences of poor glycemic control are more severe during pregnancy compared to non-pregnant states.

Risks for the fetus

High blood sugar and insulin levels during the first trimester, when major organs develop, can cause congenital abnormalities such as heart defects (truncus arteriosus, atrioventricular septal defect, single ventricle complex) and central nervous system malformations (sacral agenesis, holoprosencephaly, longitudinal limb deficiency). These complications are rare and can be averted with tight blood sugar control. Pregestational diabetes does not increase the likelihood of chromosomal alterations like Down Syndrome. Miscarriages are increased due to abnormal early development. After birth, the neonate may experience jaundice, hypoglycemia, macrosomia, and underdeveloped lungs causing respiratory problems. Hypoglycemia can occur if the mother's blood sugar was high near delivery, prompting excess fetal insulin production. A hyperglycemic maternal environment is associated with future obesity, insulin resistance, type 2 diabetes, and metabolic syndrome in the offspring. Mild neurological and cognitive deficits—including increased ADHD symptoms, impaired motor skills, and impaired explicit memory—have been linked to pregestational type 1 diabetes and gestational diabetes.

Diabetes pregnancy management

Blood glucose should be regulated as strictly as possible. During the first weeks, less insulin may be required due to tight control and fetal glucose demand; basal and bolus insulin may need reduction to prevent hypoglycemia. Frequent blood sugar testing is recommended. As pregnancy progresses, placental hormones cause insulin resistance, often increasing insulin needs. Maintaining target blood sugar is important because the baby produces extra insulin in response to maternal hyperglycemia, which can cause macrosomia. During delivery, insulin needs decrease; after delivery, insulin demand returns to pre-pregnancy levels. Management includes meal planning (cutting sweets, three small meals and one to three snacks daily, balanced fiber intake), increased physical activity (walking, swimming, aquaerobics), and frequent blood glucose monitoring. Targets are below 95 mg/dL on awakening, below 140 mg/dL one hour after a meal, and below 120 mg/dL two hours after a meal. Results should be recorded and reviewed by the health care team. Many women require extra insulin during pregnancy; insulin is not harmful to the baby. The National Institute of Health and Care Excellence recommends closed-loop insulin systems for all pregnant or planning women with type 1 diabetes.

Breastfeeding

Breastfeeding is generally beneficial for the child of a mother with diabetes, potentially lowering the child's risk of developing type 2 diabetes later in life and helping maintain healthy infant weight. However, diabetic breast milk has elevated glucose and insulin levels and decreased polyunsaturated fatty acids. Ingestion of diabetic breast milk has been linked to delayed language development on a dose-dependent basis. In some cases, women may be encouraged to express and store colostrum during pregnancy in case of low blood sugar after birth, though no evidence exists on the safety or potential benefits of this practice before birth.

Classification

The White classification, named after Priscilla White, assesses maternal and fetal risk. It distinguishes gestational diabetes (type A) from pregestational diabetes. Gestational diabetes has two classes: A1 (diet controlled) and A2 (medication controlled). Pregestational diabetes classes include: B (onset at age 20 or older or duration less than 10 years), C (onset age 10–19 or duration 10–19 years), D (onset before age 10 or duration greater than 20 years), E (overt diabetes with calcified pelvic vessels), F (diabetic nephropathy), R (proliferative retinopathy), RF (retinopathy and nephropathy), H (ischemic heart disease), and T (prior kidney transplant). Earlier onset or longer duration carries greater risk.