Pregnancy and Maternal Adaptation

Question 1

pregnancy symptoms

Answer 1

• Missed menstrual period
• Excessive tenderness in breasts
• Fatigue
• Change in appetite
• May have spotting or light, irregular menstrual low
• Morning sickness
  o Nausea and vomiting in 1st trimester
  o Evolutionary adaption to avoid teratogens/toxins
  o Can be caused by increase in hCG

Question 2

pregnancy tests

Answer 2

• Measure human chorionic gonadotropin (hCG)
• Placenta produces hCG, also called the pregnancy hormone as early as 10 days after the first missed period (~around two weeks after conception)
• Home pregnancy tests measure hCG in urine
  o are ~ 97% accurate when done correctly
• More accurate is blood test for hCG
  o quantitative blood test: measures exact amount of hCG in the blood
  o qualitative blood test: hCG blood test gives a simple yes or no answer

Question 3

pregnancy

Answer 3

• Lasts for ~40 weeks/280 days, after last day of menstruation
• Pregnancy divided into 3 sections of 3 months each – trimesters
• 1st trimester: months 1-3
• 2nd trimester: months 4-6
• 3rd trimester: months 6-9
• Obstetrician: care of pregnant women and developing foetus
• Gynaecologist: specialised in care of female reproductive system

Question 4

first trimester (initial development and rapid growth)

Answer 4

• Initial development and rapid growth of embryo in first 8 weeks after conception, Fetal stage from 9 weeks – birth
• organogenesis
• At the end of the first month, the embryo has a heartbeat, a two-lobed brain, and a spinal cord.
• By the end of the second month, the embryo is recognizable as a human and is called a fetus.
• After two months, the fetus has started to form arms and legs as well as fingers, ears, and toes.
• The fetus can be visibly identified as a male or female.
• By the end of the first trimester, the heart has four chambers.

Question 5

second trimester (foetus continues to form)

Answer 5

• By the end of the fourth month, fingernails, toenails, eyebrows, and eyelashes have developed
• Teeth begin to form, lips appear, and head hair may begin to grow.
• Movement of the fetus can be felt by the mother.
• Fetus can bend its arms and make a fist
• During the fifth month, the heartbeat can be detected by a stethoscope
• By the end of the sixth month vernix (keeps body from dehydrating and skin from getting wrinkled) appears on baby

Question 6

third trimester (growth)

Answer 6

• By the seventh month lanugo (fine hair grown to insulate the fetus) appears on the baby
• By the eighth months fetus growth slows down and moves into a head-down position
• By the ninth month the fetus is full term
• Skin is smooth and waxy looking
• The eyes are usually gray
• Languo drops off

Question 7

maternal adaptations to pregnancy - anatomical changes

Answer 7

• Reproductive organs become engorged with blood
  o Chadwick’s sign: vagina develops purplish hue
  o Breasts enlarge, and areolae darken
• Uterus expands, occupying most of abdominal cavity
• Lordosis occurs with change in center of gravity
• Placenta secretes Relaxin hormone –> causes pelvic ligaments and pubic symphysis to relax to ease birth passage
• Weight gain of 10-13kg is usually seen

Question 8

maternal adaptations to pregnancy - metabolic changes

Answer 8

• Placental hormones:
• Human placental lactogen (HPL):
  o Stimulates maturation of breasts, fetal growth, and glucose sparing in mother (reserving glucose for fetus; may cause gestational diabetes mellitus)
• Parathyroid hormone and vitamin D levels stay high throughout pregnancy to ensure adequate calcium for fetal bone mineralization
• Increased appetite & energy requirements

Question 9

maternal adaptations to pregnancy - physiological changes

Answer 9

• Morning sickness
• Increased urine production is due to increased maternal metabolism and fetal wastes
• Frequent, urgent urination and stress incontinence may occur as bladder is compressed
• Estrogens may cause nasal edema and congestion
• Blood volume increases 25–40% to safeguard against blood loss during childbirth
• Cardiac output rises as much as 35-40% to propel greater volume around body
• Venous return from lower limbs may be impaired, resulting in varicose veins

Question 10

hormones in pregnancy

Answer 10

1. Maintain pregnancy
2. Prepare for delivery
3. Prepare for breast feeding

Question 11

development of foetal circulation

Answer 11

• First blood cells arise in yolk sac
• Unique vascular modifications seen only during prenatal development:
  o Umbillical cord connects embryo to the placenta
  o 2 Umbilical arteries and 1 umbilical vein

Question 12

3 vascular shunts

Answer 12

1. Ductus venosus: umbilical vein drains into ductus venosus which empties into inferior vena cava
   - bypasses liver
2. Foramen ovale: opening in interatrial septum bypasses pulmonary circulation
3. Ductus arteriosus:
   - bypasses pulmonary circulation
   - pulmonary trunk drains into ductus arteriosus, which drains into aorta

Question 13

circulation in foetus

Answer 13

1. Oxygenated blood from umbilical vein
2. Ductus venosus shunts oxygenated blood from placenta past the semi-functional liver into inferior vena cava towards the heart
3. Oxygenated blood enters from inferior vena cava into the right atrium of the heart
4. Foramen ovale allows blood from right atrium directly into left atrium
5. Ductus arteriosus connects aorta with pulmonary artery: shunts blood away from non-functional lungs
6. Blood flow is into the left ventricle (5a), and from there it is pumped through the aorta into the body (5b)
7. Some moves to umbilical arteries, and re-enters the placenta
   - carbon dioxide and other waste products from the fetus are taken up and enter the maternal circulation

Question 14

after birth

Answer 14

• When the infant breathes for the first time –> decrease in resistance in pulmonary vasculature
• Pressure in the left atrium to increase relative to the pressure in the right atrium
• Results in closure of the foramen ovale –> then referred to as the fossa ovalis
• Closure of the Ductus venosus
• Closure of the Ductus arteriosus

Question 15

pregnancy hormones

Answer 15

• Corpus Luteum continues to act as endocrine gland for up to 3 months –> maintaining pregnancy –> negative feedback to hypothalamus and anterior pituitary
• Secreted progesterone inhibits further development of antral follicles
• After 3 months progesterone production is taken over by the placenta

Question 16

pregnancy

Answer 16

• Placenta becomes established roughly 5 weeks after implantation - makes hormones
• becomes source of estrogen and progesterone after 8 weeks of pregnancy

Question 17

placental functions

Answer 17

• Supplies fetus with oxygen
• Supplies fetus with nutrients
• Passes out wastes from the fetus
• Endocrine secretion
• Metabolism - glycogen, cholesterol and fatty acid synthesis

- Placenta acts as
o lungs
o kidneys
o GIT
o Skin

Question 18

placental hormones include

Answer 18

• Steroid hormones: Estrogens & Progesterone
• Peptide hormones: Human chorionic gonadotrophin (hCG), Human Placental Lactogen (hPL) and others
• Prostaglandins

Question 19

3 factors affecting foetal growth

Answer 19

Fetal factors: Genetic makeup of fetus (~40%), sex, production of fetal hormones and growth factors eg. thyroxine, insulin and insulin-like growth factors

Placental Factors: Placental size, surface area for diffusion, transport processes, hormone production, umbilical blood flow

Maternal Factors: Maternal age and size, uterine blood flow, nutrition, diseases (e.g. diabetes, infections etc.), drugs

Question 20

twin pregnancies

Answer 20

• Twin pregnancies are on the rise (during IVF more than one embryo transferred)
• Increased frequency with increased age (ovulatory cycles are not regular anymore)
  Monozygotic twins = identical twins:
• Develop from one zygote -> Have same chromosomes & will always be same sex
  Dizygotic twins = fraternal twins:
• Develop from two fertilized ova -> Have different chromosomes
• Can be same sex or opposite sex
• They develop in separate amniotic sacs and have separate umbilical cords and placentas

Question 21

conjoined twins (Siamese twins)

Answer 21

• Are identical twins joined in utero
• Rare, occurring in ~ 1:200,000 live births
• Origins of conjoined twins probably due to fission
• Conjoined twins share a single common chorion, placenta, and amniotic sac
• Surgical teams are increasingly capable of separating many such pairs
• Conjoined twins share one amniotic sac and its fluid

Question 22

prental tests: ultrasound = sonogram

Answer 22

• High-frequency sound waves used to image the developing baby as well as the mother’s reproductive organs
• Can detect sex, check fetal heartbeat, estimate due date, check for multiple pregnancies, diagnose ectopic pregnancies, detect anatomical anomalies including cleft palate and lip, anencephaly, spina bifida, club food, heart defects etc.
• Advanced ultrasounds include 3-D ultrasound and 4-D ultrasound (= 3D plus movement video), as well as fetal echocardiography (ultrasound that looks in detail at the fetus’ heart)

Question 23

prenatal tests: amniocentesis

Answer 23

• Amniotic fluid surrounding fetus is removed through a fine needle inserted into the uterus through the abdomen
• Amniotic fluid contains fetal cells and other substances
• Usually scheduled between the 15th and 18th week of pregnancy
• Can be used to assess fetal health in particular birth defects including Down syndrome, Sickle cell disease, Cystic fibrosis, Muscular dystrophy, Tay-Sachs and similar diseases and infections, sex
• Procedure has a small risk of
  o miscarriage
  o Injury to the baby or mother, infection, preterm labor
• Generally only offered to women with:
  o Abnormal ultrasound or abnormal lab screens
  o Family history of certain birth defects
  o Previous child having a birth defect

Question 24

chorionic villus sampling (CVS) test

Answer 24

• Done during early pregnancy
• Biopsy is taken of the villi in the placenta
  A) trans-cervical procedure
  B) trans-abdominal procedure
• Performed at 10 to 14 weeks of pregnancy (earlier!)
• Tests for sickle cell anemia, hemophilia
• Risk of miscarriage following CVS is ~1:100

Question 25

gestational diabetes mellitus

Answer 25

• Abnormally raised blood sugar levels that may occur in the second part of the pregnancy usually around the 24th - 28th week of pregnancy
• 3-7% gestational diabetes
• Hormones from the placenta can cause cells to become insulin resistant
• Gestational Diabetes Mellitus does not affect mother after baby is born but women who develop gestational diabetes have an increased risk of developing type 2 diabetes later in life
• Baby will not be born with diabetes
• Usually no symptoms but baby often larger
• All women screened for gestational diabetes at 24 -28 week routine check up  glucose tolerance test (ingestion of 75g glucose drink after fasting)

Question 26

preeclampsia

Answer 26

• Dangerous complication of pregnancy that can result in deterioration of placenta and insufficient placental blood supply  can lead to fetus being starved of oxygen
• Marked by high blood pressure, failing kidneys - protein in the urine, and sometimes swelling in the feet, legs, and hands
• Condition usually appears late in pregnancy >20 weeks, though it can happen earlier
• Most often seen in first-time pregnancies, in pregnant teens, and in women over 40 (Affects ~1:10 pregnant women)
• Precursor to the more serious, potentially fatal eclampsia (seizures & coma)  < 1:100 women with preeclampsia will develop eclampsia
• Preeclampsia is typically treated with magnesium sulfate

Question 27

diet and exercise during pregnancy

Answer 27

• Increases chances of a healthy baby
• Increases the chances of baby with proper birth weight
• Keeps mother healthy during pregnancy
• Helps mother lose the weight faster after pregnancy
• Decrease chances of birth defects
• Some sports should be avoided (contact sports, activities where falling is likely e.g. skiing, horse riding)

Question 28

folate and folic acid supplements during pregnancy

Answer 28

• Folate is a B group water-soluble vitamin needed for healthy growth and development
• This vitamin is known as ‘folate’ when found naturally in food (green leafy vegetables, fruit, legumes), and as ‘folic acid’ when added fortified or in dietary supplements
• Folate is and is easily destroyed by cooking
• Proven to be particularly important for the development of the nervous system and for preventing neural tube defects (spina bifida)
• Supplements should contain ≥400 micrograms folic acid
• Advised to start taking them before you fall pregnant

Question 29

iron supplements during pregnancy

Answer 29

• Need for iron increases significantly during pregnancy
• Maternal blood volume increases by ~50%
• Iron is critical for oxygen transport and healthy growth and development of the fetus and placenta
• Anemia during pregnancy has been associated with preterm delivery, maternal depression and infant anemia
• Recommended intake ~27 mg iron per day (e.g. through prenatal vitamins)

Question 30

vitamin D supplements during pregnancy

Answer 30

• Fat soluble vitamin important for immune function, bone health and cell division
• Current recommended intake of vitamin D during pregnancy is 600 IU per day
• Environmental factor that can contribute to development of Multiple Sclerosis (autoimmune disease destroying nerve insulation in the brain)
  o “No factor is more strongly associated with MS risk than latitude”.
  o Effect is important in early life: childhood and adolescence
  o In particular exposure to ultraviolet (UV) light important
  o Sunlight is a major factor in the body’s synthesis of vitamin D