Ob Week 1

Zygote (Pre-embryonic period)

Fertilization through first two weeks

Embryo (Embryonic period)

Third through eighth week

Fetus (Fetal Period)

9th through 40th week or birth

Placenta function depends on

Maternal blood pressure

Placenta Functions

• Endocrine gland

• Respiratory organ

• Nutrition

• Excretion

• Storage

Placental Hormones:

• Human Chorionic Gonadotropin (HCG)

  • Sustains corpus luteum which produces progesterone

  • Detected in pregnancy test

• Progesterone

  • Most important as it maintains uterine lining & pregnancy

  • Relaxes smooth muscle

• Estrogen

  • Promotes uterine and breast growth

  • Stimulates uterine contractions

• Human Placental Lactogen

  • Increases availability of glucose for fetus by decreasing insulin sensitivity in mother

  • Levels increase steadily during pregnancy

  • Plays a role in breast development for lactation

• Relaxin

  • Works with progesterone to inhibit uterine activity, softens connective tissue & relaxes pelvic joints

Fetal membrane is made up of:

Chorion which is the outermost layer of the fetal membrane and is on fetal side of placenta. Contains the major umbilical blood vessels. Amnion which is the innermost layer of the fetal membrane. Embryo draws amnion around itself forming a fluid filled sac which later adheres to the chorion.

Chorioamnioitis:

infection of both membranes which can lead to the baby becoming septic and potentially the mother

Amniotic fluid is made up of? How much amniotic fluid?

Two sources:

• Fluid from maternal blood transported across amnion

• Fetal urine

800-1000 mL at full term

Oligohydramnios:

less than 300 mL of amniotic fluid which can be related to a problem with fetal renal development

Polyhydramnios:

greater than 2000 mL of amniotic fluid which can be related to GI problem on maternal side

Components of amniotic fluid:

Lecithin & Sphingomyelin

Determines fetal lung maturity

Umbilical cord

AVA; One vein; two arteries

Vein: carries oxygenated blood from placenta to fetus

Arteries: carries deoxygenated blood from fetus to placenta

Whartons jelly: specialized connective tissue prevents compression of blood vessels

Fetal Circulation:

Oxygenation occurs in placenta with three shunts required for fetal systemic circulation

• Ductus Venosus: usually closes at clamping of the cord and officially closes by send of first week

• Ductus Arteriosus: Begins to constrict after first few breaths, functional closure by 72 hours with complete closure between 3-4 weeks of age

• Foramen Ovale: functional closure within 1-2 hours of birth, physiologic closure by 1 month of age and permanent closure by 6th month

Fetal respiratory system

maturity coincides with establishment of surfactant during gestational week 36. L/S ratio of 2:1 measured to determine maturity

Gravid

woman who is pregnant

Gravida

number of pregnancies, including current

Para

Number of pregnancies that reached viability (20 weeks)

Primigravida

Women who is pregnant for the first time

Multigravida

Pregnant women who has been pregnant before

Multipara

women who has delivered mor than one viable fetus

Nulligravida

Women who has never been pregnant

Nulllipara

woman who has not carried a fetus to viability

GTPAL

Gravida (pregnancies)

Term births or pregnancies delivered (37+)

Premature births (20-36.6 weeks)

Abortions (spontaneous or induced)

L number of living children

Naegles rule

What is used to calculate women’s date of delivery.

• Identify first day of last menstrual period (LMP)

• Subtract three moths

• Add seven days

• Adjust year by adding one year (If needed)

OR

• Add nine months to LMP

• Then add 7 days

Presumptive signs of pregnancy

Those that suggest but don’t positively indicate pregnancy

• Amenorrhea

• Nausea/vomiting

• Breast changes

• Urinary frequency

• Fatigue

• Quickening (fluttering sensation when fetus moves) 16-20 weeks of gestation

Probable signs of pregnancy

Strong indications of pregnancy, short of confirmation, two or more are highly suggestive of pregnancy, detected about 12th week

• Pigmentation changes

• Abdominal enlargement

• Chadwicks sign (purplish color of cervix)

• Hegars sign (softening of lower uterus)

• Ballottement (rebounding of fetus floating in amniotic fluid when cervix pushed

• Braxton hicks contractions

• Goodells sign (something of normally firm cervix)

• Positive pregnancy test (hCG levels)

Positive signs of pregnancy

Absolute confirmation of pregnancy

• Detection of fetal heart rate

• palpation of fetal movement

• ultrasonic evidence of a fetus

Trimesters

First: First day of LMP to week 13

Second: 14-27 weeks

Third: 27- 40 weeks

Full term pregnancy is 38-42 weeks

Common prenatal labs and tests

• CBC

• Blood typing

• Rubella titer

• Hepatitis B

• HIV testing

• Serology/VDRL (tests for syphilis)

• STI screening (Chlamydia, gonorrhea, herpes)

• Pap smear (Cervical cancer screening)

Rh Sensitization:

• May occur when maternal is Rh negative but fetus is Rh positive

• If infants Rh blood enters mothers circulation her body perceives this blood type as harmful therefore creating anti-Rh + antibodies in response

• Although current infant is not affected, next pregnancy is at risk, if that fetus also has Rh + blood, mothers antibodies will attack developing fetus causing hemolysis (break down) of its red blood cells. Known as erythroblastosis fetalis

• Treatment: RhoGAM 300 mcg I.M. given prophylactically at 28 weeks gestation and again within 72 hours of birth. Second dose is only given in infant is Rh +

  • RhoGAM is also given after abortion, ectopic pregnancy, & an amniocentesis as in each case blood could exchange

Routine prenatal care consists of:

• Prenatal visits

• Blood pressure

• CBC

• Weight

• Abdominal exam

• Assess fetal heart rate

• Assess fetal position