Embryology and pregnancy

Gestation period

The entire pregnancy period starting at fertilization to birth (38 week)

Prenatal period

Period before birth where the embryo is developing

All principal adult organs are present

foetal development

Entire fetal development

Placenta is fully functional

Neonatal period

First 42 days after birth takes place

Physiology of lactation

is the production and release of milk

Prolactin from anterior pituitary increases during pregnancy

• Progesterone inhibits effect of prolactin until delivery ​

• After delivery, progesterone levels drop​

• Suckling increases the release of prolactin & oxytocin (milk ejection reflex)​

• Nursing causes neural feedback to the hypothalamus and the anterior pituitary gland​

• Which stimulates the production of PRF and prolactin​

• Helps mammary glands prepare for the next nursing period​

  When suckling stops, milk secretion stops ​

Milk ejection reflux

Oxytocin cause milk to become released into the mammary ducts

Stimulation of touching nipple causes hypothalamus to release oxytocin

Oxytocin causes a contraction of myoepethelial cells

Milk is moved from the alveoli into mammary ducts

Oxytocin release by other stimuli (Hearing a babys cry)

Stages of labour

Dilation​

• 6-12 hours​

• Regular contractions of the uterus ​

• Rupture of amniotic sac & dilation of cervix (10cm)​

Expulsion

• 10 minutes to several hours​

• Baby moves through birth canal​

Placental ​

• 30 minutes​

• Afterbirth is expelled by uterine contractions ​

• Constrict blood vessels that were torn​

• Reduce the possibility of haemorrhage​

True vs false labour

True labour begins when uterine contractions occur at regular intervals, usually producing pain​

• Other signs of true labour may be localization of pain in the back, which is affected by walking​

• Dilation of the cervix​

• “Show” signs (discharge of blood-containing mucus from the cervical canal)​

​

False labour produces pain at irregular intervals but there is no cervical dilation​

Positive feedback during labour

• Uterine contraction forces foetal head into cervix (stretch)​

• Nerve impulses reach hypothalamus causing release of oxytocin ​

• Oxytocin causes more contractions producing more stretch of cervix and more nerve impulses​

Anatomical and physiological changes during pregnancy

• Weight gain​

• Increased protein, fat & mineral storage​

• Marked breast enlargement​

• Lower back pain​

• Increase in heart rate by 10-15%​

• Pulmonary function alterations​

• GI tract compressed ​

• Heartburn & constipation​

• Pressure on bladder​

• Glomerular filtration rate rises​

• Compression of vena cava​

• Varicose veins & oedema in the legs​

• Skin may display increased pigmentation

Lactation

Production and release of milk