Does early growth delay occur in diabetic pregnancy?

OBJECTIVE: To identify the date of ovulation in pregnant women with Type 1 diabetes in order to assess the validity of the concept of early growth delay. DESIGN: Identification of ovulation by measurement of urinary luteinising hormone and assessment of fetal growth using ultrasound scan. SETTING: Diabetic pre-pregnancy and antenatal clinic in a teaching hospital. SUBJECTS: Twenty women with Type 1 diabetes who had attended a pre-pregnancy clinic. MEASURES: Urinary LH, by laboratory and kit methods, during conception cycles. Human chorionic gonadotrophin measured in early pregnancy. Early ultrasound scans by a single observer blind to menstrual and ovulation dates. OUTCOME: Gestation calculated from ovulation date and gestation estimated from menstrual dates, compared with gestation at age indicated by early ultrasound scan. RESULTS: When the date of ovulation was identified in 20 women with Type 1 diabetes there was no evidence of growth delay in any pregnancy. When gestation was estimated from menstrual dates there was apparent early growth delay in six pregnancies. CONCLUSION: This study, together with others discussed, indicates that early growth delay is probably an artefact of incorrectly estimated ovulation date.