Diurnal nonstress test variations in the human fetus at risk

Objective:

To compare the results of the nonstress test (NST) performed at 9.00pm and 9.00am on women with high-risk pregnancies.

Method:

The NST was performed two hours after a meal, at 9.00am and 9.00pm, in a quiet room exposed to daylight, on 80 women with high-risk singleton pregnancies. Each session lasted 20 minutes. If the NST was nonreactive, the entire biophysical profile was immediately performed. The women's blood pressure was measured before, ten minutes within, and at the end of the NST. Women who smoked or had uterine contractions were excluded from the study.

Results:

Diurnal NST variations were manifested by a higher incidence of reactive NSTs and an increased number of fetal heart accelerations after 9.00pm (82.5%) than at 9.00am (68.8%) (P <0.027, P <0.001).

Conclusions:

Evening appointments for fetal assessments, except in emergency conditions, may eliminate the need for additional tests such as the entire biophysical profile because of the decreased incidence of nonreactive NSTs. Evening NSTs would save time and decrease maternal anxiety.

Babazadeh R, Abdali K, Lotfalizadeh M et al. International Journal of Gynecology and Obstetrics, vol 90, no 3, September 2005, pp 189-192.

Author abstract. © Elsevier Ireland Ltd.