A placenta previa in which the placental edge just reaches the internal os is more commonly known as:

Choice A reason: Vibroacoustic stimulation is a technique that uses sound to stimulate the fetus and elicit a response. It is sometimes used in conjunction with the nonstress test (NST), not the CST. The NST measures the fetal heart rate (FHR) in response to fetal movement, while the CST measures the FHR in response to uterine contractions.

Choice B reason: A negative CST result means that the FHR does not show any late decelerations during at least three contractions in a 10-minute period. Late decelerations are decreases in the FHR that begin after the peak of a contraction and return to the baseline after the contraction ends. They indicate uteroplacental insufficiency, which means that the placenta is not delivering enough oxygen and nutrients to the fetus. A negative CST result is reassuring and suggests that the fetus is well-oxygenated and can tolerate labor².

Choice C reason: The CST is not an invasive test, as it does not involve inserting any instruments or devices into the uterus or the fetus. However, it does require stimulating contractions, either by giving the pregnant woman oxytocin (a hormone that causes uterine contractions) or by having her rub her nipples (which also releases oxytocin). The contractions can be uncomfortable and may trigger preterm labor in some cases.

Choice D reason: The CST is not more effective than the NST if the membranes have already been ruptured. In fact, the CST is contraindicated (not recommended) in women who have ruptured membranes, as it can increase the risk of infection and bleeding. The NST is a safer and simpler alternative to the CST, as it does not require stimulating contractions. However, the NST may not be as reliable as the CST in detecting fetal compromise.

Choice A reason: Maternal placenta previa is not a common complication of gestational diabetes mellitus. Placenta previa is a condition in which the placenta covers the cervix, which can cause bleeding and preterm labor. The risk factors for placenta previa include previous cesarean delivery, multiple pregnancy, advanced maternal age, and smoking.

Choice B reason: Maternal hyperemesis and neonatal low birth weight are not directly related to gestational diabetes mellitus. Hyperemesis is a severe form of nausea and vomiting during pregnancy that can cause dehydration and weight loss. The causes of hyperemesis are not well understood, but it may be influenced by hormonal changes, genetic factors, and psychological factors². Neonatal low birth weight is defined as a birth weight of less than 2,500 grams, which can be caused by many factors, such as prematurity, intrauterine growth restriction, maternal infection, and maternal malnutrition.

Choice C reason: Maternal premature rupture of membranes and neonatal sepsis are not specific to gestational diabetes mellitus. Premature rupture of membranes is a condition in which the amniotic sac breaks before labor begins, which can increase the risk of infection and preterm delivery. The causes of premature rupture of membranes are not clear, but some possible factors include infection, inflammation, stress, and trauma. Neonatal sepsis is a life-threatening infection in newborns, which can be caused by bacteria, viruses, or fungi. The risk factors for neonatal sepsis include prematurity, low birth weight, maternal infection, and invasive procedures⁵.

Choice D reason: Maternal preeclampsia and fetal macrosomia are the most common and serious complications of gestational diabetes mellitus. Preeclampsia is a condition characterized by high blood pressure and protein in the urine, which can lead to organ damage, seizures, and death. The exact cause of preeclampsia is unknown, but it may be related to abnormal placental development, immune system dysfunction, and genetic factors⁶. Fetal macrosomia is a condition in which the baby is larger than normal, usually weighing more than 4,000 grams at birth. This can cause difficulties during labor and delivery, such as shoulder dystocia, birth trauma, and cesarean section. The main cause of fetal macrosomia is excessive maternal glucose, which stimulates fetal insulin production and growth.