Gestational diabetes

What is it?

In pregnancy, hormones from the placenta make the body less responsive to insulin. That is normal, and it exists to keep more sugar available for the baby. In some people the pancreas cannot keep up, and blood sugar rises. That is gestational diabetes. ¹

Sugar crosses the placenta. Insulin does not. So the baby receives the extra sugar and responds by making their own insulin.

Insulin is a growth hormone. Extra insulin drives growth, particularly in tissue that responds strongly to it, which is the trunk, the shoulders and the fat stores. The head grows more normally.

That produces two distinct consequences.

At delivery. A baby with a relatively larger trunk and shoulders is more likely to have a shoulder dystocia, where the head is born and the shoulder is caught. For the same birth weight, a baby of a mother with diabetes carries a higher risk than one whose mother did not have it. ³

After delivery. At birth the sugar supply stops instantly. The baby's insulin production does not stop as fast. Blood sugar can fall quickly, and it can fall without any symptoms. That is why these babies are screened on a schedule rather than watched for signs. ²

Diabetes also affects lung maturation, which is why babies of mothers with diabetes can have breathing difficulty even at term. ⁵

What does standard care look like?

Screening in pregnancy, typically between 24 and 28 weeks, with earlier testing for those at higher risk. Guidance sets out the approaches. ¹

Management, starting with diet and activity, with medication where blood sugars remain above target. Guidance addresses the options. ¹

Monitoring of fetal growth, with the limits of weight estimation acknowledged. ⁴

Antenatal fetal surveillance where indicated. ¹

A discussion about timing and mode of delivery, including the lower estimated weight threshold at which cesarean may be considered for people with diabetes. ⁴

Preparation for shoulder dystocia at the delivery. ³

Newborn blood glucose screening on a defined schedule, because babies of mothers with diabetes are in the group for whom screening is recommended. ²

Postpartum follow-up of the mother's own glucose, since gestational diabetes is associated with later type 2 diabetes. ⁶

What can go wrong?

Not screened for, or screened late. ¹

Diagnosed and not managed, with blood sugars left above target.

Fetal growth not monitored where diabetes was known. ⁴

The delivery discussion not had, where estimated weight crossed the threshold guidance addresses. ⁴

The newborn not screened for low blood sugar, or not screened on the recommended schedule. This is the most consequential and most preventable failure on this page. ² See missed hypoglycemia.

A low bedside glucose reading not confirmed on a laboratory sample, or not rechecked after treatment. ²

No postpartum glucose follow-up for the mother. ⁶

Whether any of this amounts to a departure from the standard takes a physician expert reading the whole record.

Which injuries can follow?

For the baby

• Low blood sugar and brain injury, which is the injury most specific to this event. ²
• Cortical visual impairment, the characteristic consequence of significant hypoglycemic brain injury. ⁷
• Shoulder dystocia and brachial plexus injury. ^{3 8}
• Clavicle fracture.
• Respiratory distress, from delayed lung maturation. ⁵
• Jaundice, which is more common in these babies. ⁹
• HIE, where a prolonged shoulder dystocia interrupts oxygen supply. ¹⁰

For the mother

• Preeclampsia, which is more common. ¹¹
• Higher rates of cesarean and of severe perineal tearing. ¹²
• Later type 2 diabetes. ⁶

What does this look like in the records?

From the prenatal record

• Screening results and the date. ¹
• Blood sugar records through the pregnancy.
• Any medication started, and when.
• Growth scans with estimated fetal weights. ⁴
• Any documented discussion about mode and timing of delivery.

From the labor and delivery record

• The delivery note and any shoulder dystocia note. ³
• The birth weight.
• The cord blood gas and Apgar score scores. ¹³

From the newborn record, which is the important part

• Every blood glucose value with the exact time it was taken. ²
• Whether low bedside readings were confirmed in the laboratory.
• What was done after each low reading, and what the recheck showed.
• Feeding records.
• bilirubin values with times. ⁹
• The newborn examination, including arm movement. ⁸

What can you do this week?

1. Request the complete labor and delivery record for you and your baby. The records request builder writes the letters for you.
2. Write down what you remember while it is fresh, using the delivery timeline builder.
3. Read how to read your labor and delivery records before the records arrive.
4. Check the deadline to file in your state with the statute of limitations lookup.