Ultrasound estimated fetal weight slightly below the median is associated with increased risk of spontaneous preterm birth.

Background: This study investigates the possible relationship between ultrasound estimated fetal weight (EFW) at third trimester and the risk of preterm birth following spontaneous preterm labor in otherwise uncomplicated pregnancies.

Methods: We performed a nested case-control study including 281 cases of spontaneous preterm labor with preterm delivery in the third trimester and 3372 matched controls within a cohort of 6207 consecutive pregnant women. Pregnancies with fetal growth restriction (birth weight <10th centile of population-based normograms) or fetal anomalies were not included.

The increase of blood flow in the fetal middle cerebral artery correlates with the onset of labor at term.

The objective of this cohort study is to evaluate the relationship between blood flow resistance in the fetal middle cerebral artery (MCA) and the beginning of spontaneous labor. A group of consecutive women (n = 664) with a singleton pregnancy was submitted to Doppler examination of fetal MCA between 24 and 41 weeks' gestation (median, 35 weeks). The study population was later divided into 2 groups according to the MCA pulsatility index (PI), expressed in multiples of the median (MoM) for each gestation week.