Final answer:
When membranes rupture, the first action a nurse should take is to check the fetal heart rate to ensure the fetus's well-being, followed by assessing the color of the amniotic fluid, monitoring signs of infection, and documenting the rupture event.
Step-by-step explanation:
When the membranes rupture, indicating a potential onset of labor or a complication such as preterm premature rupture of membranes (PPROM), the initial action a nurse should take first is a) Check the fetal heart rate. This is a critical first step to ensure the well-being of the fetus as it assesses for any immediate distress or changes in the fetal condition caused by the rupture. After checking the fetal heart rate, the nurse should then assess the color of the amniotic fluid to check for any signs of meconium or infection, monitor for signs of infection, and document the time of rupture. These steps will aid in determining the appropriate course of action to ensure the health and safety of both the mother and the baby.