Preconception Care Fertilisation, Embryology Fetal Development

1. Preconception Care & Fertilisation, Embryology & Fetal Development Effective Midwifery practice Level 6 Kate Quarrell

2. Health

3. Statistics 40% of pregnancies are not planned (BBC News 2004) Some texts state 50% 1:4 pregnancies result in miscarriage 15.1% of all stillbirths are from congenital abnormalities whilst 50% of stillbirths are unexplained (CEMACH 2006) Neonatal deaths 48% are from immaturity and 22.4% from congenital abnormalities (CEMACH 2006)

4. Why Preconception care?

5. Pre conception care continued Example of smoking. Smoking in pregnancy has been positively linked to prematurity, low birth weight and stillbirth. Subsequently the baby is 15 times more at risk of sudden infant death syndrome. Example of social factors. Infants born to families of socio-economic groups IV & V are twice as likely to die between the end of the first month of life and 1 year. Example of maternal disease. Babies born to women with Type 1 or 2 diabetes have a 3.8 times higher perinatal mortality rate with congenital abnormality nearly twice that expected (CEMACH 2006 p 22)

6. Why study embryology? Knowledge is the key to un locking our minds to release us to provide the appropriate care. What do we need to know about embryology? Significant times in embryo development Processes involved in that development What can hinder healthy embryo and fetal development?

7. Significant landmarks - Fertilisation Formation of diploid zygote – single cell from fusion of haploid gametes. Gametes formed by cell division known as meiosis which is a process by which the chromosome content is reduced to 23. (Spermatogenesis or Oogenesis) Process allows for mixing of maternal and paternal genes

8. Problems Spontaneous abortion Genetic disorder. Anomalies of the base within the DNA so all cells affected e.g. Phenylketonuria. 50% associated with chromosomal abnormalities More common in older women – probably associated with nondisjunction of chromosomes e.g. Down’s syndrome

9. Mitosis Mitotic cell division – formation of Cells have identical genetic material Totipotent – clones Day 4 16-20 cells & is known as a Morula

10. Blastocyst Cells division becomes asymmetrical Cells polarise Loose their totipotency and begin to differentiate Inner cell mass – fetus Outer cell mass becomes the trophoblast which develops into the placenta Implants day 6

11. Problems with Implantation Example Pelvic inflammatory disease, commonly develops between 15 -24 years. Ectopic pregnancy 1:10 Structural anomalies of the uterus might inhibit implantation Intrauterine contraceptive disease

12. Cells 350 different types of human cells Different functions Cells process: division, differentiation, induction, migration & death

13. By day 14 From implantation of the blastocyst the inner cell mass is known as the embryo Epiblast & Hypoblast = Bilaminar embryonic disc Primitive streak develops – significance is the threshold at which experimentation must stop. Amniotic & Chorionic cavities

14. Embryo 3-8 weeks Critical time for normal development Particularly sensitive to external factors, environmental hazards, pharmacological agents, drug misuse Organogenesis Trilaminar disc folds into C shaped cylindrical embryo Co-ordinated by genes – Homeobox Cell differentiation Tissue interaction & communication Folding is due to different rate of growth

15. Gastrulation Cell migration and rearrangement – Week 3 Primitive streak in the midline Bilaminar disc is converted into Trilaminar disc 3 Germ layers :Ectoderm, Mesoderm & Endoderm 2mm long Notochord forms Primitive heart Mother first missed menstrual period

16. Trilaminar disc Ectoderm will form the epidermis & central nervous system Mesoderm will form the bones, muscles and heart, blood vessels, kidneys and reproductive organs Endoderm will form digestive tract, respiratory tract, glands & mucous membranes

17. Formation of the Neural tube - Neurulation Starts at 22- 23 days Folding starts in the middle in both the cranial and caudal direction. Cranial opening closes day 25 , caudal opening closes on day 27days Folic acid is involved in DNA synthesis Most women at this stage do no know they are pregnant

18. Development of the skeletal vertebral column Commences at week 4 Week 6 cartilaginous stage Week 8 Ossification begins

19. Week 4 Heart begins to beat approximately 85 beats /minute Outline of eyes Upper limb buds Lungs begin to form Parts of gastro intestinal tract can be identified.

20. Week 8 Heart has 4 chambers Upper limbs longer bent at the elbows Fingers distinct but webbed External genitalia still in sexless state but have begun to differentiate By end of week 8 all body systems & organs are formed.

21. Summary of human development Growth – cell division Morphogenesis – Development of form. Movements of sheets & masses of cells Differentiation – Maturation of cells. Formation tissues and organs. (Moore & Persuad 2003)

22. 8-12 Weeks Eye lids fuse Fetal circulation functioning Moves freely Kidney’s function fetus passes urine ~10 weeks Abdominal gut needs to be withdrawn into cavity by week 10 Ossification of bones begins 8 weeks

23. By 20 Weeks Most organs capable of functioning Neurons formed between 10-18 weeks Skin covered with vernix and lanugo Brown fat deposited Limbs are at mature proportions Meconium present in gut

24. 24 Weeks Skin – thin, wrinkled, translucent & dark red Lungs terminal sac phase (surfactant started to be produced 22weeks, increases significantly after 30weeks) Sensory organs develop, fetus responds to noise Length 32 cm Weight 700g Periods of sleep & activity

25. 28 Weeks Survival possible Eyelids open Length 37cm Weight 1200g Head circumference 26cm Girl – small labia majora Boy – scrotum – few rugae

26. 32 Weeks Lanugo disappears from face Ear cartilage soft Lengths 43cm Weight 2000g Accumulation of fat

27. 36 Weeks Head circumference > abdominal circumference Plantar creases visible Head hair lengthens Nails reach the tips of fingers Lanugo vanishes from shoulder Breast tissue nodule present 1-2 mm Skin pale Length 49cm Head circumference 33cm Weight 2900g