Consecutive measurements show association of IGF-1 with preterm delivery in type 1 diabetic pregnancy

Aim: Few data on insulin-like growth factor 1 (IGF-1) and preterm delivery are reported in type 1 diabetes mellitus while cross-sectional studies with regulators of IGF-1 indicate association with preterm delivery and fetal growth. We evaluated time-course relationship between the maternal serum IGF-1 and the subsequent obstetrical outcome. Setting and design: Consecutive follow-up study of 130 pregnant women with type 1 diabetes recruited for measurement of growth factors and evaluated for diabetes status and adverse perinatal outcome. Serum was drawn for measurement of IGF-1 at every fourth week during pregnancy until week 30, then every second week. Preterm was defined as delivery before week 36. Arterial stiffness index was calculated from diurnal blood pressure measurements. Birth weight was adjusted for gender and gestational age by calculating a birth weight ratio. Results: Diabetic women who delivered preterm had lower IGF-1 levels throughout pregnancy. Measured consecutively with all data present, IGF-1 in week 14 to 32 was consistently lower compared with women who delivered after gestational week 35 adjusted for albumin excretion rate preeclampsia, arterial stiffness index, duration of diabetes, and parity (p<0.05). Low birth weight in terms of birth weight ratio (<1.22) was associated with lower IGF-1 from week 14 to 32; also, when adjusted for preterm delivery, albumin excretion rate, and preeclampsia (p<0.05). Birth weight ratio was higher in women delivering preterm compared to women delivering at term. Conclusion: Preterm delivery showed an association with consecutive IGF-1 values from week 14 to 32. Fetal growth was not impeded in preterm delivery in diabetic pregnancy. Women with type 1 diabetes mellitus deliver preterm at much higher rates than non-diabetic women and in case of nephropathy the incidence is nearly 50% [9-11]. Thus, important comorbidities are factors for the preterm delivery in diabetes, i.e. glycemic malregulation, increased albumin excretion in urine, and retinopathy have shown associations with preterm delivery. Early onset of labor or premature rupture of membranes are among the conditions that lead to delivering preterm; however, background variables like preeclampsia and hypertensive complications are more common. The latter is easily detectable but antihypertensive treatment is mainly symptomatic to gain time and advance gestation before delivery [12]. Preterm delivery poses significant risk in diabetic pregnancy affecting fetal growth, too, and the causative pathways are poorly described. The aim of the present study was to investigate the time-course relationship between the maternal serum IGF-1 and the subsequent obstetrical outcome in diabetic pregnancies with various levels of background risk. Accordingly, we included pregnancies of women with different levels of albumin excretion rate (AER) and preeclampsia. Correspondence to: Finn Friis Lauszus, senior consultant, Department of Gynecology and Obstetrics, Herning Hospital, Gl. Landevej 61, DK-7400 Herning, Denmark, Tel: +45 78 42 36 14; Fax: +45 78 43 46 36; E-mail: finlau@rm.dk