Endocrine Abstracts

Background: Abnormal uterine artery Doppler (UtAD) at 23 weeks is considered to be a risk factor for FGR. However, the incidence of being born small for gestational age (SGA) in those with abnormal Doppler is not defined.

Aims: 1. To determine the incidence of birthweight<2^nd centile (BW<C2nd) in pregnancies at high risk of FGR.

2. To determine the effect of specific antenatal FGR risk factors on fetal growth trajectory and birthweight.

Methods: Data were obtained from women seen in a clinic for those at high risk of FGR. Entry criteria were low first trimester PAPP-a or second trimester raised inhibin +/− AFP. Pregnancies were categorised according to FGR risk subgroup; small placenta (<10 cm) and abnormal 23 week UtAD (defined by pulsatility index>1.3MoM, resistance index>0.7MoM +/− notching on one or both waveforms (group A), small placenta & normal UtAD (B), normal placenta & abnormal UtAD (C), normal placenta & normal UtAD (D). Estimated fetal weight and birthweight centiles were calculated, customised for maternal height, weight, ethnicity, gestation and sex.

Results: 226 pregnancies that resulted in livebirths >34 weeks gestation were analysed (A; 16, B; 18, C; 40 and D; 152) of which, 20 (9%) were SGA births. The proportion of babies with BW< C2nd was highest in group A (4/16, 25%), compared with group B (1/17, 6%), C (9/40, 23%) and D (6/152, 4%). ANOVA analysis of fetal growth trajectories between 23 weeks and birth showed differences between FGR risk groups in Δ weight (A=2.10 kg, B=2.73, C=2.42, D=2.66, P=0.001). Mean birthweight (A=2.64 kg, B=3.33, C=3.02, D=3.26, P<0.01) and mean birthweight centiles (A=15.8th, B=36.6th, C=28.3^rd, D=37.9th, P=0.008) were also significantly different.

Conclusions: In pregnancies considered to be at higher risk of FGR, 9% were born SGA, rising to 25% for those with a small placenta and abnormal UtAD. Serum markers combined with UtAD and to a lesser extent, placental size can be used to identify adverse growth trajectory and small size at birth.