Summary OB WEEK 1 NOTES | VEFIFIED NOTES

OB WEEK 1 NOTES Conception & Fetal Development Preconception Counseling Help moms get in best health prior to conception Get chronic illnesses into good control Change diet or medications to improve outcomes o #1 thing to take prior to conceiving = folic acid (production of RBC, prevent neuro- tube defects) o Diabetic meds – vasoconstriction in placenta and calcification o BP meds Improve long term health of mom and fetus/baby The Ovum • Erupts from the ovarian follicle; is collected by the Fimbria • High estrogen levels enhance ciliary action in the fallopian tubes, so they capture the ovum and begin moving it toward the uterus • If not fertilized within 24 hours, the ovum degenerates The Sperm • 200-500 million sperm enter the vagina with ejaculation • Transit time to the site of fertilization ranges from 5 minutes to 6 hours • Enzymes are produced in the head of the sperm during travel to aid in penetrating the ovum Fertilization • Requires favorable vaginal pH, favorable cervical mucus, • Access to the cervix • Mature sperm • Occurs in the ampula (outer third) of the fallopian tube Forms a hollow ball of cells called blastocyst (embryo develops from this layer) the outer layer of cells is the trophoblast The Zygote • Moves down the fallopian tube over 3-4 days • Cells continues to multiply • Forms a solid ball of 16 cells Implantation • 7-10 days after conception, portions begin to burrow into the endometrium • This is implantation • (Some women experience implantation bleeding) *Dating Pregnancy * • 10 lunar months • 9 calendar months • 40 weeks • 280 days New lingo to learn* o EDC - Estimated Date of Confinement o EDD - Estimated Date of Delivery o EDB – Estimated Date of Birth o LMP - Last Menstrual Period o LNMP - Last Normal Menstrual Period Not included is spotting from getting pregnant o EDC is 40 weeks from the first day of the LNMP estimated 2 weeks +/- Embryo - Lasts from day 15 until 8 weeks after conception Development of the embryo • Amniotic fluid • Yolk sac (1st 2-3 weeks) • Umbilical cord two arteries, 1 vein • Wharton’s jelly if none, compresses core cutting off O2 supply • Placenta developing/embedding • Human chorionic gonadotropin (HCG) • Structure • Functions • Crown to rump length is 3 cm • At end of 8 weeks, all organ systems are present • The embryonic stage is the most critical time in development of organs and external features. • The baby is most vulnerable to teratogens during this time. Teratogens * - Nongenetic factors that cause malformations and disorders in utero. - Known human teratogens are drugs, chemicals, infections, and exposure to radiation, heavy metals and certain maternal conditions/infections. Membranes: • Chorion Chorionic villi burrow into the decidua and become the placenta MOMS side • Amnion Covers the umbilical cord and fuses with the chorion on the fetal side of the placenta BABY side Smooth white side of placenta = baby side Amniotic fluid* • Diffusion from maternal blood, outflow from fetal lungs, fetal urine • 700-1000 ml at term – fetus swallows and urinates Amniotic Fluid Abnormalities *Oligohydramnios - <500 ml of amniotic fluid - Too little can indicate Respiratory, urinary system problem or placental insufficiency something could be wrong with kidneys or lungs *Polyhydramnios - >2000 ml amniotic fluid – too much, related to maternal diabetes, neural tube defects, chromosomal deviations and malformations of the CNS &/or GI • Functions - thermoregulation, oral fluid, cushion from trauma, freedom of movement for