Background
Foetal distress is the distress of the foetus prior to or during labour and is used to describe foetal hypoxia.

Aims
As exact determination of foetal middle cerebral artery (MCA) to umbilical artery resistance index (RI) ratio has important role in the diagnosis of foetal distress, any factor that can alter this ratio can affect diagnosis of foetal distress. Therefore, we decided to investigate the role of maternal position and its effect on foetal MCA/umbilical artery RI ratio.

Methods
In this quasi-experimental study, a total of 27 pregnant mothers who aged 17 to 43 years and gestational age range of 26 to 39 weeks were studied by colour Doppler ultrasound. RI of the MCA and umbilical artery was measured at three positions, namely supine, right lateral decubitus, and left lateral decubitus positions.

Results
There was no significant difference regarding MCA/umbilical artery RI ratio between supine and right lateral decubitus (P=0.48), right and left lateral decubitus (P=0.67), and supine vs. left lateral decubitus (P=0.39). Likewise, no difference was seen regarding MCA/umbilical artery pulsatility index (PI) between supine and right lateral decubitus (P=0.20), right and left lateral decubitus (P=0.35), and supine vs. left lateral decubitus (P=0.80).

Conclusion
Maternal position did not have significant effect on MCA/umbilical artery RI ratio.