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Pregnancy: diabetes mellitus

Diabetes mellitus may be a pre-existing problem or develop during pregnancy, gestational diabetes. It complicates around 1 in 40 pregnancies

Risk factors for gestational diabetes
BMI of > 30 kg/m^2 previous macrosomic baby weighing 4.5 kg or above. previous gestational diabetes first-degree relative with diabetes family origin with a high prevalence of diabetes (South Asian, black Caribbean and Middle Eastern)

Screening for gestational diabetes if a women has had gestational diabetes previously an oral glucose tolerance test (OGTT) should be performed at 16-18 weeks and at 28 weeks if the first test is normal women with any of the other risk factors should be offered an OGTT at 24-28 weeks currently the same WHO diagnostic criteria are used as for non-pregnant patients. There is however increasing evidence that a lower threshold should be used as treating borderline patients improves both maternal and neonatal outcomes

NICE issued guidelines on the management of diabetes mellitus in pregnancy in 2008

Management of pre-existing diabetes weight loss for women with BMI of > 27 kg/m^2 stop oral hypoglycaemic agents, apart from metformin, and commence insulin folic acid 5 mg/day from pre-conception to 12 weeks gestation detailed anomaly scan at 18-20 weeks including four-chamber view of the heart and outflow tracts tight glycaemic control reduces complication rates treat retinopathy as can worsen during pregnancy

Management of gestational diabetes responds to changes in diet and exercise in around 80% of women oral hypoglycaemic agents (metformin or glibenclamide) or insulin injections are needed if blood glucose control is poor or this is any evidence of complications (e.g. macrosomia) there is increasing evidence that oral hypoglycaemic agents are both safe and give similar outcomes to insulin hypoglycaemic medication should be stopped following delivery a fasting glucose should be checked at the 6 week postnatal check
Pregnancy: diabetes - complications

Maternal complications

polyhydramnios - 25%, possibly due to fetal polyuria preterm labour - 15%, associated with polyhydramnios

Neonatal complications

macrosomia (although diabetes may also cause small for gestational age babies) hypoglycaemia respiratory distress syndrome: surfactant production is delayed polycythaemia: therefore more neonatal jaundice malformation rates increase 3-4 fold e.g. sacral agenesis, CNS and CVS malformations (hypertrophic cardiomyopathy) stillbirth hypomagnesaemia hypocalcaemia shoulder dystocia (may cause Erb's palsy)

Chickenpox exposure in pregnancy

Chickenpox is caused by primary infection with varicella zoster virus. Shingles is reactivation of dormant virus in dorsal root ganglion. In pregnancy there is a risk to both the mother and also the fetus, a syndrome now termed fetal varicella syndrome

Fetal varicella syndrome (FVS) risk of FVS following maternal varicella exposure is around 1% if occurs before 20 weeks gestation studies have shown a very small number of cases occurring between 20-28 weeks gestation and none following 28 weeks features of FVS include skin scarring, eye defects (microphthalmia), limb hypoplasia, microcephaly and learning disabilities

Management of chickenpox exposure if there is any doubt about the mother previously having chickenpox maternal blood should be checked for varicella antibodies if the pregnant women is not immune to varicella she should be given varicella zoster immunoglobulin (VZIG) as soon as possible. RCOG and Greenbook guidelines suggest VZIG is effective up to 10 days post exposure consensus guidelines suggest oral aciclovir should be given if pregnant women with chickenpox present within 24 hours of onset of the rash
Hypertension in pregnancy

The classification of hypertension in pregnancy is complicated and varies. Remember, in normal pregnancy: blood pressure usually falls