Birth-- Parturition Birth (parturition) Delivery: A pregnancy lasts approximately 40 weeks. Fetus shifts downward and is in contact with the cervix. Labour begins (uterine contractions) Birth-- Parturition Cervix dilates (10 cm is full dilation) Amnion membrane ruptures (water breaks) Cervical canal is forced open and the baby is delivered Birth-- Parturition birth is normally head first; feet-first (breached birth) can be problematic After delivery, a wave of contractions deliver the placenta (after birth) after delivery, the umbilical cord is cut and tied forming the navel Placental afterbirth Some animals eat eat their placenta after birthing it Some humans do too?! Birth Sequence Birth-- Parturition Hormonal Control Progesterone levels drop before delivery. Receptor cells in the uterus stimulate the hypothalamus to release the hormone oxytocin from the post. pituitary. Oxytocin stimulates the uterus to begin uterine contractions (labour) drip: An IV of oxytocin to speed up labour. The hormone relaxin is released by the placenta prior to labour. It causes ligaments in the pelvis to loosen for easier delivery. Birth Parturition and Hormones Birth-- Parturition Hormonal Control Progesterone levels drop before delivery. Receptor cells in the uterus stimulate the hypothalamus to release the hormone oxytocin from the pituitary. Oxytocin stimulates the uterus to begin uterine contractions (labour) drip: An IV of oxytocin to speed up labour. The hormone relaxin is released by the placenta prior to labour. It causes ligaments in the pelvis to loosen for easier delivery. Birth-- Parturition Trauma of Birth this is why some women have water births, to lessen the impact of the environmental changes Baby moves from a world of darkness to light. World of constant temperature of 37 o to room temperature of o. Aquatic world to dry air (terrestrial) World of food and oxygen supplied by the placenta to the need of a digestive and respiratory system World of waste removal by the placenta to the need of a digestive, urinary and respiratory system Ace Ventura 2 Rhino Birth National Geographic Birth Videos Odon Device Easing births Birth-- Parturition Physical changes at birth 1. Lungs must empty of fluid and go from non functional to gas exchanging in under 5 min. Crying is good!!! 2. Prior to birth, the ductus arteriosus (a small shunt between the pulmonary artery and the aorta) and the foramen ovale (a hole in the septum between the right and left atria) allowed most of the blood to bypass the lungs. At birth these close failure causes the blue baby syndrome (may correct itself with time or it may need surgery). Fertilization to Birth---- Video BIRTH VIDEO Lactation Prolactin from the pituitary gland promotes milk production in the mammary glands. Prolactin production is inhibited during pregnancy due to the high levels of progesterone and estrogen secreted by the placenta. Lactation Sucking, causes receptors in the nipples to send reflex input to the hypothalamus. The hypothalamus then stimulates the posterior pituitary to release oxytocin. Oxytocin allows milk produced in the breast glands to be forced into ducts leading to the nipple. Prolactin stimulates the mammary glands to manufacture milk. Oxytocin triggers the release of milk into the ducts leading to the nipple. Reproductive Technologies IVF- In Vitro Fertilization Egg Retrieval ICSI intracytoplasmic sperm injection ICSI Blastocyst