Which of the following is a contraindication for tocolysis?

Tocolysis, the use of medications to suppress premature labor, is contraindicated in cases of chorioamnionitis due to the associated risks for both the mother and the fetus. Chorioamnionitis is an infection of the amniotic fluid and membranes that can occur when there is a prolonged rupture of membranes or other factors. When this condition is present, further delaying the delivery through tocolytic therapy can exacerbate the infection and lead to severe maternal and neonatal complications, including sepsis, fetal distress, and increased morbidity and mortality.

In contrast, the other conditions listed, such as gestational diabetes, mild preeclampsia, and severe morning sickness, do not pose the same level of immediate risk if tocolysis were to be attempted. While these conditions must certainly be managed appropriately, they are not considered contraindications for the use of tocolytics in the same way that chorioamnionitis is. Thus, the presence of chorioamnionitis clearly highlights a critical, acute situation where intervention is required to protect both maternal and fetal well-being, negating the use of tocolytic therapy.