The Development of the Embryo through to Birth Unit 4

Conception How does conception happen? http://www.youtube.com/watch?v=9CO5Nl_ngCo

The sperm approaching the egg Sperm & egg join in the fallopian tube 46 chromosomes combine, which pre-determine all of a person’s physical characteristics

Fertilized Ovum 30 hours after conception No larger than a pin head Rapidly dividing The fertilized Ovum is called a Zygote Floats down from the fallopian tube towards the uterus

3 Weeks Once in the Uterus, the developing embryo, called a Blastocyst, searches for a nice place to implant It actually burrows beneath the surface of the uterus The yolk sac produces blood cells during the early weeks of life It is only one sixth of an inch long The backbone, spinal column, and nervous system are forming. The kidneys, liver and intestines are taking shape

4 Weeks The embryo produces hormones which stop the mother’s menstrual cycle

5 Weeks Embryo is size of a raisin Day 21 – the heart has begun beating Neural tube enlarges into 3 parts, soon to become a very complex brain The placenta begins functioning The spine and spinal cord grows faster than the rest of the body and gives the appearance of a tail. http://pregnancy.about.com/od/pregnancycalendar/ig/Early-Ultrasound-Photos/

6 & 7 Weeks 7 weeks – facial features are visible, including a mouth & tongue The eyes have a retina & lens The major muscle system is developed The embryo practices moving and has its own blood type The blood cells are produced by the liver now instead of the yolk sac http://pregnancy.about.com/od/pregnancycalendar/ig/6-Weeks-Pregnant.-Tgk/

8 Weeks Embryo now called a foetus Is about half an inch long Is protected by the amnionic sac, filled with fluid The foetus swims and moves gracefully Arms & legs have lengthened Fingers can be seen Toes will develop in the next few days Brain waves can be measured http://pregnancy.about.com/od/pregnancycalendar/ig/8-Week-Ultrasound-Photos/

10 Weeks Heart is almost completely developed and very much resembles that of a newborn baby The blood is diverted away from the lungs by an opening of the atrium of the heart and the presence of a bypass valve The blood is oxygenated through the placenta 20 tiny baby teeth are forming in the gums http://pregnancy.about.com/od/pregnancycalendar/ig/10-Week-Ultrasound-Photos/

12 Weeks Vocal chords are complete Can and does sometimes cry (silently) Brain is fully formed Can feel pain May suck his/her thumb Eyelids now cover the eyes, and remain shut until the 7th month to protect the delicate optical nerve fibres

14 Weeks Muscles lengthen and become organised Mother will soon start feeling first flutters of the feotus kicking and moving

15 & 16 Weeks 15 weeks – The feotus has an adults taste buds and may be able to savour the mother’s meals 16 weeks – 5 and a half inches tall 6 ounces in weight Eyebrows, eyelashes and fine hair appear The foetus can grasp with his/her hands, kick, or even somersault http://pregnancy.about.com/od/pregnancycalendar/ig/16-Week-Ultrasound-Photos/

20 Weeks 20 weeks – can hear & recognise mother’s voice Still small & fragile but growing rapidly Could possibly survive if born Finger nails and finger prints appear Sex organs are visible What happens during an ultra sound? http://video.about.com/pregnancy/Ultrasound.htm Ultrasound device can tell if girl or boy and pick up certain abnormalities such as Spina Bifida, Cleft Lip/Palate etc.

24 Weeks Covered with a fine downy hair called Lanugo Tender skin is protected by a waxy substance called vernix At birth- substance may still be on the skin but it will be quickly absorbed Breathing is practiced by inhaling amnionic fluid into developing lungs http://pregnancy.about.com/od/pregnancycalendar/ig/24-Week-Ultrasound-Photos/

30 Weeks The umbilical cord has been the lifeline to the mother Nourishment is transferred from the mother’s blood, through the placenta, and into the umbilical cord to the feotus If mother ingests toxic substances i.e. alcohol/drugs, the baby receives these as well http://pregnancy.about.com/od/pregnancycalendar/ig/30-Week-Ultrasound-Photos/

32 & 36 Weeks 32 weeks – The foetus sleeps 90-95% of the day Sometimes experiences REM sleep, an indication of dreaming Summary - Ultrasounds week by week http://www.youtube.com/watch?v=gfgq7WiHbh4

40 Weeks Now approx 7 & a half pounds Is ready for life outside its womb Vaginal Delivery: http://video.about.com/pregnancy/Delivery.htm Caesarean http://video.about.com/pregnancy/Cesarean-Section.htm Real Life C-Section http://www.babycenter.ca/video/pregnancy/c-section/ http://www.mayoclinic.com/health/c-section/MM00531 At birth the placenta will detach from the side of the uterus. Umbilical cord will cease working as the first breaths are taken. Child’s breathing will trigger changes in the structure of the heart and bypass arteries which will force all blood to now travel through the lungs.