Fetal Development and Maternal Adaptations During Pregnancy

Conception

The union of a single egg from the female and sperm cell from the male.

Fertilization

Occurs when a sperm successfully penetrates the membrane surrounding the egg

occurs when egg and sperm combine and chromosomes merge

Implantation

Occurs between 6-8 days after fertilization. The fertilized cell implants itself into the endometrial lining of the uterus

zygote

cell formed by fertilization event between two gametes.

Is a combo of the DNA from each gamete

During fertilization the zygote secretes

hCG

implantation occurs

6-10 days after fertilization, zygote implants in the upper portion of the uterus

there may be some light bleeding

hCG: human chorionic gonadotropin

• produced by the developing embryo and placenta

• stimulates corpus luteum to continue hormone production

• is pregnancy test hormone

Estrogen and progesterone

• Produced by corpus luteum until 10 weeks, then by placenta

Estrogen

stimulates uterine growth

increases breast development and vascularity of breast tissue

Causes hyperpigmentation in the skin

Progesterone

Secreted by the ovarian corpus luteum during the first ten weeks, then placenta.

Maintains lining of the uterus to support pregnancy

aids in breast development

Relaxes smooth muscle- GI and uterine muscles

considered the pregnancy hormone

teratogen

substance that has the potential to cause a defect in an unborn child

Physical agents

radiation exposure and hyperthermia

Biological infectious agents

• rubella

• cytomegalovirus

• varicella

• herpes simplex

• toxoplasma

• syphilis

Chemical agents

• alcohol

• certain drugs

• mercury and lead poisoning

• nicotine and smoking

Categories of medicine

A: controlled studies show no risks

B: no evidence of risk in humans, chance of fetal harm is remote

C: risk not excluded. Adequate studies lacking, chance of fetal harms but benefits outweights the risks

D: Positive evidence of risk.

X: contraindicated

Nageles rule

LMP: first day of last menstrual period minus 3 months and add 7 days

Most accurate way to determine EDD

ultrasound measuring crown to rump length

Gravida

A woman who is pregnant

Para

the number of pregnancies in which the fetus/fetuses have reached 2- weeks of gestation of more

Multigravida

a woman who has had two or more pregnancies

primagravida

a woman who is pregnant for the first time

preterm

pregnancy that has reached 20 weeks gestation but before completion of 37 weeks

term

a pregnancy from the beginning of week 38 to end of week 40

post-term

a pregnancy beyond 40-42 weeks of gestation

viability

capacity to live outside of the uterus occurring around 22-25 weeks gestation

Presumptive changes

felt by woman and are subjective

• quickening: perception of fetal movement

• N/V

• Breast changes- tenderness and tingling

• Amenorrhea

• Fatigue

• Positive urine test

Probable

changes observed by an examiner:

• Hegar’s sign

• Goodell’s sign

• Chadwick’s sign

• Ballotment

• Positive blood pregnancy tests

• Abdominal enlargement

Hegars sign

Softening and enlargement of the lower uterine segments felt on vaginal examination at 6-8 weeks

Goodell’s sign

softening of the cervix felt upon vaginal exam at 6-8 weeks.

Chadwick’s sign

vaginal mucosa discoloration: often a blue tint

Ballotment

Lower uterine segment or the cervix tapped by the examiners finger and left there, fetus floats upward and then sinks back down causing a gentle tap (felt at 16 weeks)

Positive signs

attributed only to the presence of a fetus

• fetal heart tones

• Visualization of the fetus on US

• palpate and visualize fetal movements

Can see heart beat on US at how many weeks

6

Primagravida

a woman who is pregnant for the first time

multigravida

a woman who has had two or more pregnancies

GTPAL

1. Gravity

2. term births- 37.1-40.0 weeks

3. preterm births- 20.1-37.0 weeks

4. abortions

5. living children

Doctors appointments for uncomplicated pregnancy

Conception to 28 weeks: every 4 weeks

29 to 36 weeks: every 2 weeks

37 weeks to birth: weekly

Antepartum assessment care

• vitals

• weight

• urine

• fundal height

• leopolds maneuvers

• fetal heart rate and activity

first trimester

1-3 months, 1-13 weeks

second trimester

4-6 months, 14-27 weeks

Third trimester

7-9 months, 28-40 weeks

What is happening during first trimester

• Period of development is the stage in which most organs are formed (heart, brain, and kidneys)

• week 1: vascular changes influenced by progesterone, prepare the uterus for implantation

• week 3: first missed period

• week 4: early breast changes and positive pregnancy test

Placenta and umbilical cord develops

throughout weeks 4-11

6th week

heart and main blood vessels are formed and heart starts beating on ultrasound

brain and spinal cord begins to form

weeks 8-12

urinary frequency, can determine boy or girl

audible heart rate- 120-160

fetal respiratory movements

What is happening in the 2nd trimester

Fetal heart: audible with doppler

Quickening

Fundal height is at umbilicus at 20 weeks, goes up 1 cm per week until delivery

problems have settled down

Week 16: ballotment exam

Braxton hicks may be felt: 14-16 weeks

increased growth of mammary glands: breast enlargement

Fetal movement at 17 weeks

Month 6

• lungs are filled w/ amniotic fluid

• fat is starting to deposit under their skin

• lanugo (baby hairs) and vernix appear

Third trimester changes

• increased size of uterus

• heart burn

• SOB

• urinary frequency

• alterations in maternal posture

• abdominal wall stiations

• lightening

• weight gain- 25-30 pounds

Fetal development at 36 weeks

• fetus is 17-18 inches long, weights 5-6 pounds

• skin is smooth because fat increases

• babys movements slow down due to lack of room

• lightening occurs when the baby drops in the pelvis

at 37-40 weeks

length 18-21 inches

weights 6-9 pounds

fetus assumes head down position

well flexed extremities and head

skin is pink and smooth

Dietary recommendations

• variety of foods from all food groups

• lower intake of fats and cholesterol

• increase folic acid and iron in diet

• balance food and exercise to maintain healthy weight

folic acid

400 mcg per day for normal women

deficiency leads to neural tube defects

pregnant women need 600mcg

deficiency linked to cleft lip, cleft palate, cardiac defects

iron in pregnancy

27 mg a day

• iron from animal sources, absorbed better from plant source and fortified foods

• vitamin c increases absorption

• Milk, tea, coffee, antacids, spinach, reduce absorption (ca decreases absorption)

side effects of iron

• constipation

• nausea

• tarry stools

PICA

practice of craving and eating non-food substances

• ice, dirt, laundry starch, antacid tabs, toothpaste, coffee grounds

associated with iron deficiency anemia

gastrointestinal changes

• appetite fluctuates

• nausea first trimester

• increased appetite after first trimester

• bleeding gums

• heart burn

• constipation

• abdominal discomfort

Breast changes during pregnancy

• fullness/heaviness

• heightened sensitivity.

• nipples and areola become darker in pigment

• more vascular due to increased blood supply

• thin clear discharge

• colostrum may be expressed as early as 16 weeks

Respiratory changes

• oxygen needs increase

• uterine growth pushes diaphragm up: SOB

Muscular changes

• lordosis

• increased mobility of pelvic joints

• stretching of ligaments

Placenta

• forms at implantation

• placenta initially produces hormones to support pregnancy

• maternal-placental circulation starts around 2 weeks when embryonic heart starts to beat

• Functions:

  • respiration

  • excretion of waste

  • nutrition

  • storage

Function of placenta

• serves as the interface between the mother and the fetus

• produces hormones to control the physiology of the mother

• protects the fetus

• removes waste products from the fetus

• produces hormones that mature fetal organs

Roll of amniotic fluid

• helps maintain a constant body temp

• cushions the fetus from trauma

• allows umbilical cord to be relatively free from compression

• promotes fetal movement to enhance musculoskeletal development

Oligohydramnious

too little amniotic fluid

Polyhydramnious

too much amniotic fluid

Umbilical cord

• contains two arteries and one vein (AVA)

• Wharton’s jelly: helps protect cord

Nuchal cord

cord around the neck

Common discomforts of pregnancy

• N/V

• Urinary frequency

• backaches

• constipation

• varicose veins

• hemorrhoids

• SOB

• heartburn

• dependent edema

• leg cramps