A 30-year-old woman in labor develops recurrent late decelerations on CTG. Uterine contractions are adequate and cervix is 6 cm dilated. What is the underlying mechanism?

Correct option is B

Late decelerations occur after contractions and indicate uteroplacental insufficiency. They are due to decreased placental oxygen transfer → fetal hypoxia → chemoreceptor response.
Explanation of options: (a) ✘ Cord compression causes variable decelerations, not late ones. (b) ✔ Correct; late decelerations are classic for uteroplacental hypoxia/insufficiency. (c) ✘ Head compression produces early decelerations that mirror contractions. (d) ✘ Maternal hypotension can worsen hypoxia, but mechanism of late decels is directly placental insufficiency.