18 day grace period
no blood transfer if first 18 days, what mom ingests does not affect baby
teratogens
Non genetic
Drugs and chemicals
Infections (eg. rubella)
Radiation
Maternal health conditions (eg. diabetes)
conception
Union of a single ovum and sperm
fertilization
Takes place in fallopian tube
Sperm successfully penetrates the membrane surrounding the ovum
3 stages of pregnancy
Pre-embryonic: fertilization to 3 weeks
Embryonic: weeks 3 to 8
Fetal: weeks 8 to birth
pre-embryonic stage
-fertilization - 3 weeks
- Blastocyst attaches to endometrium and proliferates
- germ layers form
3 germ layers
-ectoderm
-mesoderm
-endoderm
ectoderm
-epidermis, sweat glands, nails, hair, lens of the eye, epithelium, glands
mesoderm
-bones, teeth, muscle, dermis, connective tissue, cardiovascular system, spleen, urogenital system
endoderm
-lining of the resp and GI tract (liver, pancreas, bladder, vagina), epithelium, GUS
Embryonic Stage
chorion
covering of the fetal side of the placenta
Contains major umbilical blood vessels
amnion
fills with amniotic fluid
amniotic fluid
Oligohydramnios
less than 300mL
Associated with fetal renal failure
Polyhydramnios
more than 1000mL
Associated with GI malformations
yolk sac
umbilical cord
placenta
fetal stage
dizygotic twins
Fertilization of 2 eggs
Fraternal
2/3
monozygotic twins
Division of one egg
Identical
1/3
complications of twin pregnancies
Often prematures
Spontaneous rupture of membranes preterm
Congenital malformations
Shunting of blood between placenta (one twin gets more blood/nutrients than other)
Congenital heart failure after birth
Higher chance of twins with fertility drugs
Generally a bit smaller than singleton pregnancy (more likely to flip)
twin chorionicity