Amniotic fluid insulin levels identify the fetus at risk of neonatal hypoglycaemia.
OBJECTIVE
To investigate the use of amniotic fluid insulin (AFI) as a predictor of neonatal morbidity in the macrosomic newborn of the diabetic mother, in view of the fact that raised AFI levels are a marker for fetal hyperinsulinaemia.


METHODS
AFI was measured by radioimmunoassay in a group of pregnant diabetic women (n = 63) with normal (n = 41) or accelerated fetal growth (n = 22).


RESULTS
Using log transformed data, liquor insulin was found to be significantly higher in pregnant women with Type 1 and Type 2 diabetes mellitus (17.6 mU/l; 95% confidence interval (CI) 11.7-26.4) compared with women with gestational diabetes mellitus (GDM) (8.2 mU/l; 95% CI 4.8-13.8, P = 0.02) or impaired glucose tolerance (IGT) (6.2mU/l; 95% CI 4.9-8.0, P = 0.0001). In the group with macrosomic fetuses (birth weight > 90th centile for gestational age), there was a significantly higher incidence of elective Caesarean section (CS) and emergency CS (12/22) compared to those with appropriate for gestational age (AGA) fetal weights (birth weight > 10th and < 90th centiles for gestational age) (9/41, P = 0.009). There was no significant correlation between raised AFI and macrosomia except in the Type 1 diabetic women, in whom the AGA group mean was 13.2 mU/l (95% CI 7.4-23.3), and 34.6mU/l (95% CI 17.5-68.4 P = 0.022) in macrosomia. In the latter group, hypoglycaemia requiring treatment was significantly more common in the macrosomic hyperinsulinaemic neonates (8/13), compared to normoinsulinaemic neonates in the same group (0/9, P = 0.005).


CONCLUSIONS
Identification of the hyperinsulinaemic fetus before delivery might allow the intensification of maternal insulin therapy leading to a reduction in incidence and severity of diabetic fetopathy. Pregnancy with a normoinsulinaemic fetus could be allowed to continue to the onset of spontaneous labour, which might result in a lower CS rate.
Fraser
R B
RB
University Department of Obstetrics and Gynaecology, Northern General Hospital, Sheffield, UK.
Bruce
C
C
D000649:Amniocentesis; D000653:Amniotic Fluid / Q000737:chemistry*; D001724:Birth Weight; D003922:Diabetes Mellitus, Type 1; D003924:Diabetes Mellitus, Type 2; D016640:Diabetes, Gestational; D005260:Female; D005320:Fetal Macrosomia / Q000175:diagnosis*; D006801:Humans; D007003:Hypoglycemia / Q000175:diagnosis*; D007231:Infant, Newborn; D007328:Insulin / Q000032:analysis*; D011237:Predictive Value of Tests; D011247:Pregnancy; D011254:Pregnancy in Diabetics; D011863:Radioimmunoassay; D012016:Reference Values; D012307:Risk Factors
D007328:Insulin