OB reproduction

fertilization of the female ovum by the male sperm

occurs when a sperm enters the ovum and their nuclei unite. Usually occurs in the outer third of the fallopian tube. Takes 3 days for the zygote to reach the uterine cavity

occurs when the embryo buries itself in the upper segment of the uterine lining

also referred to as gestation and lasts approximately 280 days (40 weeks)

• fertilization through the first two weeks.
• Period of the zygote

• third through eighth week. Highly
• vulnerable to teratogens, viruses, drugs, radiation, or infections. End of
• 8th week, all organ systems and external structures are formed and unmistakably
• human

eighth week through the fortieth week orbirth. Viability now possible at 23-24 weeks after conception

Stimulates corpus luteum to produce progesterone and estrogen until the placenta assumes that function

Produced by the ovaries during menstrual cycle. Placenta assumes production after the 6th or 7th week. Increases vascularity in the pregnant woman

Produced by the corpus luteum and then the placenta. Most important pregnancy hormone as it maintains the endometrium and prevents abortion. Relaxes smooth muscle in the pregnant woman

Increases availability of glucose for the fetus. Glucose required for fetal growth and development. Levels increase steadily during pregnancy

Inhibits uterine activity, softens connective tissue, relaxes pelvic joints to facilitate birth

· Means of metabolic exchange

· Filters some harmful substances from reaching fetus

· Covers about half uterine surface

· Function depends on maternal blood pressure

• Human Chorionic Gonadotropin (hCG)
•       ·Ensures estrogen and progesterone  
•        secretion
•      
• Human Placental Lactogen (hPL)
•       ·Facilitates glucose transport across  
•        placenta

• Progesterone 
•       Maintains endometrium 
•       Decreases contractility of uterus

• Estrogen  
•       Stimulates uterine growth   
•       Stimulates uteroplacental blood flow 
•       Stimulates myometrial contractility

• Respiration
•        Oxygen and CO2 diffuse between the   
•        placental membrane from maternal
•        blood to fetal blood

• Nutrition
•        Water, electrolytes, carbohydrates, fat,
•        protein, and vitamins pass across
•        placental membrane

• Excretion
•        Metabolic waste products cross the                 placental membrane from the fetal
•        blood into maternal blood 

       Maternal kidneys excrete the wastes

• Storage
•        Carbohydrate, proteins, calcium, and
•        iron are stored in the placenta for ready
•        access to meet fetal needs

Viruses, drugs caffeine, alcohol, nicotine, carbon monoxide and other toxic substances can cross the placental membrane

•   
• Bacteria and protozoa infect placenta first, then fetus

Outermost membrane, closest to uterine lining

Contains the major umbilical blood vessels

Chorionic villi infiltrate maternal tissues and become the fetal side of the placenta

Inner membrane

Embryo draws amnion around itself forming a fluid filled sac

Later adhears to chorion to make one membrane

Produces amniotic fluid

Infection of both of the membranes

800-1000 mL

insufficient amniotic fluid; less than 300 mL.

Can be related to problem with fetal renal development

Too much amniotic fluid; more than 2,000 mL.

Can be related to problem with fetal GI development

• Albumin
• Urea
• Uric Acid
• Creatinine
• Lechithin     (remember the L/S ratio!!)
• Sphingomyelin
• Phosphatidylgycerol (PG)
• Bilirubin
• Fat
• Fructose
• Leukocytes
• Protiens
• Enzymes
• Lanugo Hairs

• Cushions the fetus, umbilical cord
• Allows freedom of movement for muculo-skeletal development
• Keeps the baby from tangling with membranes
• Helps maintain body temperature
• Source of oral fluid and waste repository

• 30-90 cm in length
• 2 cm in diameter
• 2 arteries: carries deoxygenated blood from fetus to placenta
• One vein: carries oxygenated blood from placenta to fetus
• Wharton's jelly: prevents compression of the blood vessels

Remember --> AVA

• Fetal hemoglobin carries 20-30% more O2 than
• maternal hemoglobin
• Fetal hemoglobin concentration is about 50%
• more than maternal
• Fetal heart rate is about 110-160 BPM, therefore fetal cardiac output greater than adults

Remember: maternal and fetal blood should not mix! Mixing only occurs at time of delivery when placenta detaches. Only gasses, nutrients, wastes... should pass through placental membrane

35 weeks

Lecithin and sphingomyelin-L/S ratio measured to determine maturity

L/S ratio of 2:1 indicates fetal lung maturity

9th

16

birth

Limbs begin to form and tiny heart begins to beat

Embryo now becomes a fetus. Tiny arms and legs can now bend.

Sex is now evident. Languo covers the entire body. Yolk sac that will produce blood until the fetus can make its own (the ball in the picture)

Fetus can now hear. 4-6 oz of amniotic fluid surrounds the fetus. Fetus is 5in long, 4oz in weight.

Legs, with their bones seen through translucent skin, are in motion, even though the mother can't feel the movement.

Meconium is forming. Brown fat begins to form also. Vernix caseosa production is complete.

Bones begin to harden. Lungs begin to breathe on their own. Fetus is about 10 in long.

The eyes start to open and react to changes in light. Gets to typical fetal position. Wt 3lbs, 11in long

Continues to grow rapidly. The testes have descended fully. Nails grow past the fingertips