Question

How does oestrogen affect uterine muscle sensitivity during parturition?

Options

• It increases the number of oxytocin receptors on uterine muscles

• It decreases the number of oxytocin receptors on uterine muscles

• It suppresses the release of oxytocin from the posterior pituitary

• It inhibits uterine contractions throughout labour

Answer 1

Oestrogen, secreted by the placenta near term, increases the number of oxytocin receptors on uterine muscles. This heightened receptor sensitivity, combined with the rising oestrogen: progesterone ratio, makes the uterine muscles more responsive to oxytocin and other contraction-inducing signals during parturition.