INTRODUCTION: The objective was to evaluate the effectiveness of routine (planned) antenatal nonstress tests (NSTs) in pregnant women with preexisting diabetes.

MATERIAL AND METHODS: A retrospective single-center study of 642 consecutive pregnancies in women with preexisting diabetes who gave birth to a singleton ≥22 weeks. Weekly planned NSTs were commenced at 33-35 weeks. In pregnancies with maternal-fetal complications, the initiation and frequency of the planned NST were individualized. Daily maternal assessment of fetal activity was recommended from 28 weeks, and decreased fetal activity indicated an unplanned NST. Data were collected from medical records, and local and regional databases.

RESULTS: In total, 3016 planned NSTs were performed, with a median of five (range 0-12) tests per pregnancy. Ninety-five planned NSTs (3.1%) were abnormal, a finding confirmed by retesting the same day in 8 cases (8.4%), thus leading to delivery. Complications were present in seven of these eight pregnancies, whereas no fetal movements for the last 3 days were reported when the planned NST was performed in the eighth pregnancy. When specifically asked, 5 of the 8 women stated that they had observed decreased fetal activity preceding the planned NST. In 86 pregnancies (13.4%), maternal perception of decreased fetal activity indicated in total 127 unplanned NSTs. The combination of decreased fetal activity and further obstetrical assessment led to delivery in 10 of these pregnancies (11.6%). One stillbirth occurred at 37 weeks in a pregnancy complicated by fetal achondroplasia and polyhydramnios, where the weekly planned NSTs had been normal. The overall stillbirth rate was thus 1.6/1000.

CONCLUSIONS: Routine use of planned antenatal NSTs does not appear to be indicated in pregnancies in women with preexisting diabetes in the absence of maternal-fetal complications.