The first sign of hypovolemic shock from postpartum hemorrhage is likely to be:

Injecting the medication into the vastus lateralis. This is because the vastus lateralis is a large muscle in the thigh that is suitable for intramuscular injections in newborns³. The vitamin K injection helps prevent vitamin K deficiency bleeding, which is a rare but serious condition that can cause bleeding in the brain or other organs¹. The American Academy of Pediatrics recommends that all newborns receive a single intramuscular dose of 0.5 to 1 mg of vitamin K within one hour of birth².

Choice A is wrong because a 21 gauge needle is too large for a newborn's muscle. A 25 or 27 gauge needle is more appropriate.

Choice B is wrong because injecting at a 45-degree angle may not reach the muscle tissue. A 90-degree angle is more appropriate.

Choice C is wrong because injecting 1cc of medication is too much for a newborn's muscle. The recommended dose of vitamin K is 0.5 to 1 mg, which is equivalent to 0.05 to 0.1 mL.

To check for postpartum hemorrhage.

This is because postpartum hemorrhage is a serious and potentially life-threatening complication that can occur within 24 hours of birth or later. It is defined as a blood loss of more than 500 mL in a vaginal delivery or more than 1000 mL in a cesarean delivery. The most common cause of postpartum hemorrhage is uterine atony, which is the failure of the uterus to contract after delivery. Other causes include lacerations, retained placental fragments, coagulation disorders, and uterine rupture. Monitoring the vital signs, especially blood pressure, and pulse, can help detect signs of hypovolemia due to blood loss. Other signs include pale skin, cold and clammy extremities, delayed capillary refill, decreased urine output, and altered mental status.

Choice B is not correct because determining if the mother's milk is coming in is not the primary rationale for monitoring a new mother every 15 minutes for the first hour after delivery. Milk production usually begins around 48 to 72 hours after delivery and is influenced by hormonal changes, breastfeeding frequency, and maternal health. Although breastfeeding support is important for postpartum care, it is not a priority over checking for postpartum hemorrhage.

Choice C is not correct because monitoring the mother's blood pressure to note any elevations is not the primary rationale for monitoring a new mother every 15 minutes for the first hour after delivery. Elevated blood pressure can indicate gestational hypertension or preeclampsia, which are serious conditions that can affect postpartum women. However, these conditions are more likely to cause symptoms such as headache, blurred vision, epigastric pain, and proteinuria⁴.

Moreover, blood pressure may not be a sensitive indicator of blood loss and may remain normal until a significant amount of blood is lost¹.

Choice D is not correct because answering questions the new parents may have is not the primary rationale for monitoring a new mother every 15 minutes for the first hour after delivery. Although providing education and support to the new parents is an essential part of postpartum care, it is not a priority over checking for postpartum hemorrhage. The new parents may have questions about infant care, feeding, contraception, recovery, and other topics that can be addressed during the postpartum period.