Diabetes with Fetal Growth Restriction

Diabetes with fetal growth restriction is diabetes in pregnancy with an estimated fetal weight or abdominal circumference below the 10th centile. It arises from placental vascular disease, especially with nephropathy, hypertension or long duration of diabetes. It matters because it increases the risk of stillbirth and preterm birth, and treatment targets must avoid hypoglycaemia.

• More common with vascular disease from long-standing diabetes.
• Risk factors: nephropathy, hypertension, retinopathy, smoking, long duration of diabetes.
• Tight glucose control must not cause maternal hypoglycaemia.

Fundal height is smaller than gestation, with reduced fetal movements. Look for hypertension and proteinuria.

• Fundal height more than 3 cm below dates.
• Oligohydramnios and poor weight gain.
• Differential diagnosis: wrong dates, constitutionally small fetus, preeclampsia, chromosomal anomaly, congenital infection, placental insufficiency.
• Complications: stillbirth, fetal distress, preterm birth, preeclampsia, neonatal hypoglycaemia, neonatal death.

The approach is serial ultrasound with Doppler and fetal monitoring.

• Ultrasound: estimated fetal weight or abdominal circumference below the 10th centile; severe below the 3rd centile.
• Umbilical artery Doppler weekly or twice weekly: absent or reversed end diastolic flow is severe.
• Liquor volume, middle cerebral artery Doppler and cerebroplacental ratio, uterine artery Doppler at 20 to 24 weeks.
• Blood pressure, urine albumin to creatinine ratio, creatinine, glucose profile; cardiotocography.

The principle is fetal surveillance with timely delivery, while keeping glucose on target and avoiding hypoglycaemia.

• Supportive: admit if absent end diastolic flow or reduced fetal movements; daily fetal movement counts; avoid glucose below 3.5 mmol/L; stop smoking.
• Pharmacological: aspirin 150 mg oral at night from 12 weeks to 36 weeks; insulin adjusted to keep fasting 3.5 to 5.3 mmol/L without hypoglycaemia (isophane insulin 0.2 units/kg at bedtime plus soluble insulin 0.1 units/kg before meals as the starting plan); methyldopa 250 to 500 mg oral 8-hourly (maximum 3 g daily) or nifedipine modified release 30 to 60 mg daily for blood pressure above 140/90 mmHg; betamethasone 12 mg IM twice, 24 hours apart, before delivery under 34 weeks with insulin increased by 25 to 40 percent for 72 hours; magnesium sulphate 4 g IV over 20 minutes then 1 g/hour for 24 hours for delivery before 32 weeks.
• Procedures: delivery by caesarean section for absent or reversed end diastolic flow, abnormal cardiotocography or ductus venosus changes; delivery at 37 weeks if umbilical artery Doppler is normal, at 34 weeks for absent end diastolic flow and at 30 to 32 weeks for reversed end diastolic flow.
• Special groups: neonates feed within 30 minutes, check glucose at 2 to 4 hours, treat glucose below 2.6 mmol/L with dextrose 10 percent 2 mL/kg IV over 10 minutes; nephropathy increases the risk and needs fortnightly review.
• Red flags: reduced fetal movements, abnormal cardiotocography, absent or reversed end diastolic flow, blood pressure above 160/110 mmHg.
• Follow-up: Doppler weekly or twice weekly; growth scans every 2 weeks; postnatal glucose review.