Anatomical & Physiological Changes in Pregnancy Flashcards
2 main reasons for maternal changes
- To provide suitable environment for nutrition, growth & development of the fetus.
- To protect & prepare the mother for parturition (childbirth) & support/nurture of a newborn baby.
Size of uterus in non-pregnant women
40 - 100g
Size of uterus of a pregnant woman at 20wks
300 - 400g
Size of uterus of a pregnant woman at term (>37 wks)
800 - 1000g
Define involution & how long is it completed?
Involution in pregnancy means the shrinkage of the uterus after birth & this takes 2 months to be completed.
Explain the growth of the myometrium during pregnancy
Smooth muscle cells increase both in size (hypertrophy) & in number (hyperplasia). It is also stretched from the growing conceptus/fetus.
The wall of the uterus consists of?
3 concentric layers:
- Endometrium
- Myometrium
- Perimetrium / serosa
The myometrium is formed from how many layers?
3 intertwining layers of smooth muscle
Regions of the uterus
- Fundus
- Body
- Isthmus
- Cervix
Parts of the cervix
- Cervical canal
- Internal os
- External os
What is the principal role of the cervix?
To retain the conceptus
Explain the 4 changes of the cervix during pregnancy
- Increased vascularity
- Hypertrophy of cervical glands producing an appearance of cervical erosion.
- Increase mucous secretory tissue - antibacterial mucus plug
- Reduced collagen & increased glycosaminoglycan & water in 3rd trimester leading to changes consistent with cervical ripening.
What is the isthmus?
Junctional zone between the cervix & body of uterus
Explain the change of the isthmus in pregnancy
By the 28th-week gestation contractions produce stretching & thinning of the isthmus, which results in lower uterine segment formation.
The uterus changes in _____, ______, ______, ______ throughtout pregnancy.
size, shape, position, consistency
Explain the changes in the body of the uterus - corpus uteri
- Early pregnancy = pear shape
- 2nd / 3rd trimester = globular & ovoid
- uterine cavity = 4ml - 4000ml at term
Myometrium remains ______ until the onset of labor.
quiescent (inactive)
Explain the changes that happen to the vessels supplying the uterus.
- undergo massive hypertrophy
- uterine arteries dilate to 1.5 x non-pregnant state
- spiral arterioles 30x pre-pregnant diameter
- uterine blood flow increases from 50 ml/min (10wks) to 500-600 ml/min (at term).
What is the lining of the vagina?
Stratified squamous epithelium
The stratified squamous epithelium layer of the vagina consists of 3 layers. Name them.
- Basal layer
- Functional layer
- Cornified layer
Explain the changes that occur in the vagina during pregnancy.
The lining of the vagina hypertrophies & pH level lowers from 3.5 to 4 to help clear the vagina of bacterial infection.
How does pH level in the vagina lower?
Glycogen synthesized by high estrogen levels are broken down by lactobacilli to lactic acid lowering pH to 3.5 - 4
State the changes that happens in the musculoskeletal system
- Increase in lumbar lordosis due to enlarged uterus
- Foward flexion of the neck & downward movement of the shoulders to compensate for change in center of gravity.
- Sacroiliac joints & pubic symphysis widen
- Fluid retention may cause compression of nerves in fascial sheaths e.g. median nerve in carpel tunnel syndrome.
Musculoskeletal system is affected by?
Maternal weight gain & hormonal influence
State the characteristic skin changes that is due to Melanocyte-stimulating hormone (MSH) in pregnancy.
(Face, Nipples & Abdominal wall)
Face - chloasma / Melasma (mask of pregnancy)
Nipples - areola (dark circles of skin - dark pigmentation)
Anterior abdominal wall - linea alba becomes linea nigra (dark line)
Striae gravidarum (stretch marks) - seen on the abdominal wall, lateral aspect of thighs & breasts.
What are the 1st signs/symptoms of pregnancy shown on the breasts?
- breast tenderness & increase in size
- enlarged nipples
- increased vascularity & pigmentation of areola (dark circles around the nipples - dark pigmentation)
- prominent montgomery tubercles (hypertrophic sebaceous glands) = small bumps around the areola