During a postpartum assessment, a woman reports that her right calf is painful. The nurse observes edema and redness along the saphenous vein in the right lower leg. Based on this finding, the nurse explains that the probable treatment will involve:

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.

Sudden infant death syndrome (SIDS) is the sudden and unexplained death of an infant under one year of age. SIDS is more likely to occur when infants sleep on their stomachs or sides, or when they are propped up with pillows or other soft bedding. These positions can interfere with the infant's breathing and increase the risk of suffocation or overheating .

Choice A is incorrect because gastroesophageal reflux (GER) is a common condition in infants that causes them to spit up frequently after feeding. GER does not increase the risk of SIDS and can be managed by feeding smaller amounts, burping the infant often, and keeping them upright for a while after feeding.

Choice C is incorrect because apnea episodes are brief pauses in breathing that occur normally in infants, especially during sleep. Apnea episodes do not increase the risk of SIDS and usually resolve by six months of age.

Choice D is incorrect because sleeping for short intervals is normal for newborns, who need to feed frequently during the day and night. Sleeping for short intervals does not increase the risk of SIDS and will gradually change as the infant grows older.