Sex differences in pelvic structure

1
Sex differences in pelvic structure

• female has wider pubic symphysis (connective
  tissue between pubic bones)
• relaxin released from placenta and corpus luteum
  causes relaxation of p.s.
• Female has wider pelvic inlet
• Wider pubic arch

2
Pregnancy related testsAlpha fetoprotein test

• protein made in fetal liver
• high concentrations present in fetal blood, CSF
• protein also detected in mothers blood
• high levels may indicate neural tube defect
• low may indicate trisomy 21

3
Pregnancy-related testsAmniotcentesis

• 16th week of pregnancy
• women over age 34 (or with history of heritable
  genetic disorders)
• long needle pass thru abdominal wall to sample
  amniotic fluid

4
Amnio. Contd.

• cells in fluid are cultured
• in 4 weeks, cells are examined and screened for
  genetic disorders (40)
• risks 1.5 miscarriage rate
• disadvantage waiting period

5
Ultrasound

• sound waves applied to abdomen reflection
  detected by receiver
• size, dimension assessed
• heart rate detected
• presence of twins identified
• assess organ system development

6
Chorionic Villus Sampling

• 8-10 weeks of pregnancy
• catheter inserted thru vagina, cervix to uterus
• chorionic cells removed from placenta and analyzed

7
CV sampling

• advantage can be performed earlier than amnio
  results obtained in 4-24 hours
• disadvantages risk of miscarriage risk of
  improperly formed fingers or toes (6-11 times
  compared to amnio)

8
Parturition

• labor has three stages
• stage I cervix dilates
• stage II baby is born
• stage III afterbirth expelled
• marked by contractions (15-20 min apart)
• occurs 38 weeks after fertilization or 40 weeks
  after last menstrual period

9
Initiation of labor

• fetal adrenals produce stress hormone cortisol
  (?)
• cortisol causes release of prostaglandins from
  placenta gt contractions
• oxytocin release from pituitary gt contractions

10
Stage I

• mucus plug expelled (bloody show)
• early contractions gt cervical effacement
  (thinning)
• next, contractions open cervix to 7 cm
• Lastly, transitional stage gtintense contractions
  gt cervix dilates to 10 cm

11
Stage I, contd.

• fetus descends into pelvic basin
• pressure on pelvic floor creates urge to push
• woman is advised not to push until dilation
  reaches 10 cm (to prevent edema)

12
Think, pair, share

• Which pregnancy-related test(s) (ultrasound, MSM
  test, amniocentesis) would detect the following
  abnormalities
• Congenital adrenal hyperplasia
• Anencephaly
• Trisomy 21 (Down Syndrome)

13
Stage II

• contractions less intense than transitional stage
• duration 30 min to 2 hrs.
• mother pushes during contractions
• if necessary, episiotomy is performed

14
Stage II

• crowning occurs when head is visible and
  doesnt recede
• bones of infant skull overlap to facilitate
  passage

15
Stage II, contd.

• head usually emerges face down
• nose, mouth is suctioned
• infant rotates sideways to accommodate shoulders
• umbilical cord is clamped, cut

16
Stage III

• lasts 15-30 minutes
• contractions cause placenta to detach from
  uterine wall
• afterbirth (placenta) is expelled through birth
  canal

17
Stage III

• to facilitate, physician may massage the abdomen
  or pull umbilical cord
• massage causes uterus to contract and inhibits
  blood flow, helping to prevent hemorrhage
• oxytocin or vasoconstrictor may be given if
  bleeding is excessive

18
Drugs during delivery

• analgesics, anesthetics often used to relieve
  discomfort
• commonly used anesthetics
• epidural gt anesthetic injected into the outside
  membranes of the spinal cord
• pudendal block gt anesthetic injected into
  pudendal nerve on each side of vagina

19
Drugs, contd.

• analgesics often used to promote relaxation
  between contractions relieve discomfort
• natural birthing methods (Lamaze, Bradley) often
  used to lessen need for medication

20
Difficult deliveriesForceps deliveries

• instrument inserted into birth canal to pull /
  guide infants head
• used if head is properly positioned in pelvis,
  membranes are ruptured and cervix is dilated

21
Forceps, contd.

• medical reasons for forceps delivery
• acute fetal distress
• illness of mother
• previous c-section
• breech position
• slow labor
• vacuum method is similar

22
Cesarean deliveries

• performed after spinal block or general
  anesthesia
• 20-90 min in duration
• abdominal incision made below navel, through
  uterine wall

23
Reasons for C-section

• breech presentation
• womans pelvis is too small or fetus too large
• fetal distress
• compression of umbilical cord between head and
  birth canal
• placenta previa

24
Lactation

• pregnancy hormones caused growth of breasts
• prior to birth, glands produce colostrum
• after birth, prolactin stimulates milk production

25
Milk letdown reflex

• caused by suckling gt activates sensory receptors
  in nipple gt info to brain
• causes pituitary to release oxytocin
• oxytocin causes myoepithelial cells surrounding
  alveoli to contract

26
Milk letdown

• letdown occurs
• can be interfered with by stressors (blood vessel
  constriction)
• can become conditioned reflex
• causes shutdown of reproductive system

27
Benefits of breastfeeding for infant

• Colostrum
• produced 2-5 days postpartum
• high in protein low in fat, carbs
• contains intact cells (macrophages, lymphocytes)
• antibodies (nonspecific IgAs)

28
Mature breastmilk vs. formula

• Cows milk-based formula has 3X greater protein
  levels
• primary proteins
• in formula gt casein (causes curdling)
• in breastmilk gt whey (easily digested)
• amino acid taurine nearly absent in cows milk
  (now supplemented)

29
Breastmilk vs. formula

• same levels of fat (50) but types differ
• breastmilk has more cholesterol (protective?)
• lipase present in breastmilk
• sucrose added to formula to match high levels of
  sugar (lactose) in breast milk
• bifidus factor present in higher levels in breast
  milk (promotes growth of good bacteria)

30
Breastmilk vs. formula

• lactose promotes calcium absorption
• both may contain environmental contaminants
• viruses (HepB, HIV) can be transmitted thru
  breastmilk