Reduced growth velocity from the mid-trimester is associated with placental insufficiency in fetuses born at a normal birthweight.
BACKGROUND
Fetal growth restriction (FGR) due to placental insufficiency is a major risk factor for stillbirth. While small-for-gestational-age (SGA; weight < 10th centile) is a commonly used proxy for FGR, detection of FGR among appropriate-for-gestational-age (AGA; weight ≥ 10th centile) fetuses remains an unmet need in clinical care. We aimed to determine whether reduced antenatal growth velocity from the time of routine mid-trimester ultrasound is associated with antenatal, intrapartum and postnatal indicators of placental insufficiency among term AGA infants.


METHODS
Three hundred and five women had biometry measurements recorded from their routine mid-trimester (20-week) ultrasound, at 28 and 36 weeks' gestation, and delivered an AGA infant. Mid-trimester, 28- and 36-week estimated fetal weight (EFW) and abdominal circumference (AC) centiles were calculated. The EFW and AC growth velocities between 20 and 28 weeks, and 20-36 weeks, were examined as predictors of four clinical indicators of placental insufficiency: (i) low 36-week cerebroplacental ratio (CPR; CPR < 5th centile reflects cerebral redistribution-a fetal adaptation to hypoxia), (ii) neonatal acidosis (umbilical artery pH < 7.15) after the hypoxic challenge of labour, (iii) low neonatal body fat percentage (BF%) reflecting reduced nutritional reserve and (iv) placental weight < 10th centile.


RESULTS
Declining 20-36-week fetal growth velocity was associated with all indicators of placental insufficiency. Each one centile reduction in EFW between 20 and 36 weeks increased the odds of cerebral redistribution by 2.5% (odds ratio (OR) = 1.025, P = 0.001), the odds of neonatal acidosis by 2.7% (OR = 1.027, P = 0.002) and the odds of a < 10th centile placenta by 3.0% (OR = 1.030, P < 0.0001). Each one centile reduction in AC between 20 and 36 weeks increased the odds of neonatal acidosis by 3.1% (OR = 1.031, P = 0.0005), the odds of low neonatal BF% by 2.8% (OR = 1.028, P = 0.04) and the odds of placenta < 10th centile by 2.1% (OR = 1.021, P = 0.0004). Falls in EFW or AC of > 30 centiles between 20 and 36 weeks were associated with two-threefold increased relative risks of these indicators of placental insufficiency, while low 20-28-week growth velocities were not.


CONCLUSIONS
Reduced growth velocity between 20 and 36 weeks among AGA fetuses is associated with antenatal, intrapartum and postnatal indicators of placental insufficiency. These fetuses potentially represent an important, under-recognised cohort at increased risk of stillbirth. Encouragingly, this novel fetal assessment would require only one additional ultrasound to current routine care, and adds to the potential benefits of routine 36-week ultrasound.
['Kennedy|Lucy M|LM|', 'Tong|Stephen|S|', 'Robinson|Alice J|AJ|', 'Hiscock|Richard J|RJ|', 'Hui|Lisa|L|', 'Dane|Kirsten M|KM|', 'Middleton|Anna L|AL|', 'Walker|Susan P|SP|', 'MacDonald|Teresa M|TM|0000-0001-9099-7745']
D000222:Adaptation, Physiological D000328:Adult D001724:Birth Weight D015331:Cohort Studies D005260:Female D047109:Fetal Development D005317:Fetal Growth Retardation D020567:Fetal Weight D005865:Gestational Age D006801:Humans D056865:Ideal Body Weight D007231:Infant, Newborn D008297:Male D010927:Placental Insufficiency D011247:Pregnancy D011262:Pregnancy Trimester, Second D012307:Risk Factors D016216:Ultrasonography, Prenatal D014469:Umbilical Arteries D055815:Young Adult
Growth velocity Mid-trimester Placental insufficiency Fetal growth restriction Small-for-gestational-age Appropriate-for-gestational-age Antenatal ultrasonography