However, near the end of the pregnancy, the cervix softens and dialates. Once labor has begun, the uterine contractions dilate the cervix more and this dilation sends signals to the brain to increase oxytocin release. The increased oxytocin acts on the uterus to increase the force of contractions and also causes the production of prostaglandins in the uterine lining and placenta. The prostaglandins further increase uterine contractions. These mechanisms aid in delivery of the baby and expulsion of the placenta.
Delivery is aided by spinal reflexes and voluntary contractions of the abdominal muscles as well.
A physician will generally explain what to expect during labor and delivery. It is often helpful to attend a birthing class. Lactation as birth control Nursing prevents, in some women, the menstrual cycle from resuming after delivery while they are nursing. Prolactin acts to prevent the development of new follicles in the ovary by inhibiting the release of the hypothalamic releasing factor that stimulates LH and FSH release. Therefore, nursing, although not foolproof, provides a measure of birth control in addition to providing superior nutrition and immunoprotection to the infant.