Higher rates of large-for-gestational-age newborns mediated by excess maternal weight gain in pregnancies with Type 1 diabetes and use of continuous subcutaneous insulin infusion vs multiple dose insulin injection

Aims To compare glycaemic control, maternal and neonatal outcomes in pregnancies with Type 1 diabetes, managed either by continuous subcutaneous insulin infusion, multiple daily insulin injection or switch from multiple daily insulin injection (MDI) to continuous subcutaneous insulin infusion (CSII) in early pregnancy. Research design and methods Data from 339 singleton pregnancies were retrospectively reviewed. HbA(1c) values were measured preconception and in each trimester. In a secondary analysis, use of CSII pre-pregnancy was compared with initiation of CSII during pregnancy. Results MDI was used in 140 pregnancies (41.3%) and CSII was used in 199 (58.7%), including 34 pregnancies (10.0%) during which the women switched to CSII. In pregnancies during which CSII was used duration of diabetes [median (interquartile range) 16.0 (8.0-23.0) years vs 11.0 (5.5-17.5) years; P<0.001] was longer, and the Institute of Medicine recommendations for appropriate weight gain were exceeded more often (64.8% vs. 50.8%; P=0.01). CSII use and pre-pregnancy BMI were independent predictors of excess weight gain. There was no difference in glucose control, but CSII was associated with higher birth weight [median (interquartile range) 3720 (3365-4100) g vs 3360 (3365-4100) g; P<0.001] and higher large-for-gestational-age (LGA) rate (44.7% vs. 33.6%; P=0.04) than MDI. HbA(1c) concentration in the third trimester and excess weight gain were predictive of LGA infants [odds ratio 2.33 (95% CI 1.54-3.51); P<0.001 and 1.89 (95% CI 1.02-3.51); P=0.04]. In pregnancies where CSII therapy was initiated in the first trimester and in those with pre-pregnancy use, similar glucose control and outcome was achieved. Conclusions There was no advantage of CSII with respect to glycaemic control and neonatal outcomes. The rate of LGA neonates was higher in the CSII group, possibly mediated by excess maternal weight gain, which was more frequent than in women treated with MDI.