fetal growth

Question 1

how do you externally determine the size of a foetus?

Answer 1

• symphysis fundal height

Question 2

what are the errors in values achieved? values lower than they should be?

Answer 2

• wrong LMP date
• baby lies in a transverse line
• complications e.g. oligohydramnios
• baby is small for GA

Question 3

when are values higher then they should be?

Answer 3

• wrong LMP date
• multiple pregnancy
• maternal obesity
• large baby for GA

Question 4

what 2 factors are important for foetal growth?

Answer 4

• genetic potential

- substrate supply

Question 5

what can US scanning identify?

Answer 5

• biparietal diameter (BD)
• head circumference (HC)
• abdominal circumference (AC)
• femur length (FL)
• combines into estimated foetal weight
• normative growth curves can be obtained from each of these

Question 6

what is the growth velocity?

Answer 6

• overall rate at which an infant gains weight
• 14/15 weeks: 5g/day
• 20 weeks: 10g/ day
• 32/34 weeks: 30-35g/day
• > 34 weeks: velocity dec

Question 7

when is there the fastest velocity?

Answer 7

mid-third trimester

Question 8

describe 3 main phases normal fetal growth rates are characterised by?

Answer 8

• hyperplasia: 4-20 weeks
• hyperplasia and hypertrophy: 20-28 weeks
• hypertrophy: 28-40 weeks

Question 9

why is it hard to date the pregnancy?

Answer 9

• issues knowing LMP (planned vs unplanned, oral contraceptive use)
• important to get it right

Question 10

what are maternal factors influencing foetal growth?

Answer 10

• poverty
• mother’s age
• drug use and alcohol
• smoking and nicotine
• diseases
• mothers diet and physical health
• mother’s prenatal depression
• env toxins

Question 11

what is the most important factor influencing a babys growth?

Answer 11

malnutrition

Question 12

what are the feto-placental factors influencing foetal growth?

Answer 12

• different genotypes
• gender: males tend to be bigger
• previous pregnancy (infants heavier in 2nd and subsequent)
• hormones (e.g. IGF-1 acts to inc. mitotic drive, inc. nutrient availability for tissue accretion)

Question 13

define:
SGA
IUGR

Answer 13

• SGA: small for gestational age (infant has birth weight <10th centile)
• IUGR: failure of infant to achieve its predetermined (genetic) potential for a variety of reasons

Question 14

define:
LBW
VLBW
ELBW

Answer 14

• LBW: low birth weight <2500g (7% of deliveries)
• VLBW: very low birth weight <1500g (1% of deliveries)
• ELBW: extreme low birth weight <1000g (0.2% deliveries)

Question 15

describe the the x and y axis of the intrauterine growth chart

Answer 15

X-axis =  age
Y-axis = weight

Question 16

on the growth chart, which centile is most sensitive/ most specific?

Answer 16

• 10th: most sensitive. captures all babies with IUGR and those that are SGA
• 3rd: most specific. captures IUGR but misses some

Question 17

what are the outcomes of IUGR?

Answer 17

• most common cause of still-borns

- subsequent pregnancies may be affected

Question 18

what are the 4 categories of causes of IUGR?

Answer 18

• maternal medical factors (infection, pre-eclampsia, uterine abnormalities)
• maternal behavioural factors (alcohol)
• foetal factors: multiple pregnancy
• placental factors: placental cycts, imapired trophoblast invasion

Question 19

why is there a close link b/ IURG and pre-eclampsia?

Answer 19

• main cause of pre-eclampsia is diminished remodeling of sprial arteries by cytotrophoblasts
• causes dec. blood flow and dec. nutrient supply to placenta/foetus
• pre-eclampsai = hypertension and proteinuria