"High prepregnancy HbA1c is challenging to improve and affects insulin requirements, gestational length, and birthweight".

In this very large cohort, we found that a poor prepregnancy HbA1c is a predictor for poor glycemic control during pregnancy and that HbA1c decreases until midpregnancy and then plateaus. A very poor prepregnancy HbA1c is associated with shorter gestational length and lower birthweight, which is contrary to the common assumption that poor glycemic control leads to higher birthweight.