Evaluation of fetal growth and birth weight in pregnancies with placenta previa with and without placenta accreta spectrum.

Objectives: We evaluated fetal growth and birthweight in pregnancies with placenta previa with and without placenta accreta spectrum (PAS).

Methods: We retrospectively studied pregnant patients with placenta previa with or without PAS diagnosed at 20-37 weeks' gestation. Estimated fetal weight (EFW) percentile and fetal growth rate were calculated based on ultrasound at two timepoints: 20-24 and 30-34-weeks' gestation. Fetuses were small (SGA) or large for gestational age (LGA) when EFW or abdominal circumference was <10th or >90th percentile for gestational age, respectively. Fetal growth rate was estimated by subtracting EFW percentiles from the two ultrasounds. Birthweight in grams and percentiles were estimated via Anderson and INTERGROWTH-21 standards adjusted for neonatal sex. EFW percentiles, fetal growth rate, birth weight and birthweight percentiles were compared between patients with placenta previa with and without PAS.

Results: We studied 171 patients with and 146 patients without PAS. SGA rates did not differ between groups on first (PAS n=3, no-PAS n=3, p=0.8) or second ultrasound (PAS n=10, no-PAS n=8, p=0.8). LGA rates were similar between groups on first (PAS n=11, no-PAS n=9, p=0.8) and second ultrasound (PAS n=20, no-PAS n=12, p=0.6). The growth rate was higher in fetuses with PAS than placenta previa (1.22 ± 22.3 vs. -4.1 ± 18.1, p=0.07), but not significantly. The birthweight percentile was higher in the PAS than the placenta previa group (74 vs. 67, p=0.01). On multi-linear regression, birthweight percentile remained higher in the PAS group, but not significantly.

Conclusions: Placenta previa with or without PAS is not associated with SGA, LGA or lower birthweight.