160 likes | 350 Views
Gestation and Birth. Gestation. Gestation is the period of carrying an embryo or foetus inside the female (pregnancy). This period lasts for approximately 36 weeks (9 months). Gestation.
E N D
Gestation • Gestation is the period of carrying an embryo or foetus inside the female (pregnancy). • This period lasts for approximately 36 weeks (9 months).
Gestation • By the time the embryo is one month old it has the beginnings of a brain, gut, kidneys and a heart. • By two months, it is about 31 mm longs and has all the main organ systems including a beating heart. • The embryo is now called a foetus.
4 weeks 18 weeks 8 weeks 38 weeks
Birth • Birth is actually a series of events. • During the last few weeks of pregnancy the baby usually turns upside down so its head is pressed against the cervix.
Birth • The increased pressure on the cervix causes the pituitary to release yet another hormone, oxytocin. • Higher levels of oxytocin cause the uterine walls to contract which applies more pressure to the cervix resulting in a positive feedback loop.
Birth • As more oxytocin is released the contractions become more frequent and more intense. • The amnion breaks and amniotic fluid pours out (water breaking). • The cervix begins to dilate from the normal 5mm to about 10cm.
Birth • When the cervix is dilated the mother begins to push using her abdominal muscles and forces the baby out. • The umbilical cord is cut and soon after the placenta is passed out.