A 19-year-old G1P0 woman at 39 weeks gestation presents in labor. She denies ruptured membranes. Her prenatal course was uncomplicated and ultrasound at 18 weeks revealed no fetal abnormalities. Her vital signs are: blood pressure 120/70; pulse 72; temperature 101.0° F (38.3° C); fundal height 36 cm; and estimated fetal weight of 2900 gm. Cervix is dilated to 4 cm, 100% effaced and at +1 station. She receives 10 mg of morphine intramuscularly for pain and soon after has spontaneous rupture of the membranes. Light meconium-stained fluid was noted and, five minutes later, the fetal heart rate tracing revealed variable decelerations with moderate variability. What is the most likely cause for the variable decelerations?A. Umbilical cord compressionB. MeconiumC. Maternal feverD. Uteroplacental insufficiencyE. Morphine administration
