<prompt> Which of the following explanations is not an explanation for decreased variability of the fetal heart tracing:Fetal sleep statePrematurityBarbiturate ingestionFetal stimulation  <response>: Baseline varibility on CTG is the oscillation of baseline FHR excluding acceleration and deceleration.A varibility of 5-25 BPM is a sign of fetal well-being.Decreased varibility is seen in:Fetal hypoxiaSleep apnoeaCongenital malformationMaternal academiaInfectionDrugs given to mother such as sedatives, magnesim sulfphate, antihypertensivesWilliams 22e, p 499: Drugs given to moter which decrease the baseline varibility are:NarcoticsBarbituratesPhenothiazinesTranquilizersGeneral anaestheticsMeperidineButorphanolMgSO4According to Wiliams Increasing gestational age leads to increased baseline varibility, so it can be taken prematurity will have decreased varibility i.e. option b can be considered correct. 