Complications of Gestational Diabetes Mellitus (GDM)
If maternal glucose levels are uncontrolled, the mother and baby are at risk of complications, with the most immediate concern relating to macrosomia (birth weight greater than 4.5kg). However, high glucose levels are not the only contributors to fetal growth, which becomes important in the decision making around delivery and neonatal care when a woman has excellent glucose levels and a big baby on board.
Macrosomia can also be caused by:
Maternal complications of GDM include:
Neonatal complications of maternal hyperglycemia include:
Gestational Diabetes Mellitus (GDM) Education and monitoring
Being diagnosed with GDM is a stressful and emotional experience for a lot of women. It is important for mothers to get good advice about GDM and how she can care for herself during the pregnancy as soon as possible.
The immediate priorities for diabetes care and education are:
Depending on your local expertise, this may be GP-led, antenatal clinic-led or physician-led.
This will depend on local expertise and paediatric services.
Please refer your patient as soon as possible to an antenatal team with expertise in diabetes care. This may include a diabetes nurse educator, dietitian and a doctor with experience in diabetes care.
Third trimester growth scans are performed at 28 weeks’ and 36 weeks’ gestation to assess for signs of fetal overgrowth that may have been resulted from maternal hyperglycemia.
These signs include:
These signs of macrosomia suggest that glucose targets need to be lowered and medical treatment increased.
Remember, clinical and ultrasound estimations of fetal weight can be inaccurate, so ensure the ultrasound is performed by an experienced sonographer and compared with previous scans to assess for interval growth. These results can be used to guide the timing of delivery.
When and where to deliver
If the pregnancy is otherwise uncomplicated, the timing of the delivery will depend on whether there is evidence of macrosomia and how well the glucose levels have been controlled. The use of medications alone – Metformin or insulin – is not an indication for an earlier delivery.
For smaller hospitals, women who are identified at high risk of perinatal complications may need to be referred for delivery in a larger hospital with paediatric support. Antenatal teams in smaller hospital, you will be aware of the local policies around management and referrals of these women.
Trust your clinical decision making, the consensus of your antenatal team and the preferences of the woman: