Outcomes of fetuses with small head circumference on second-trimester ultrasonography

Objective We examined the outcomes of pregnancies in which the fetal head circumference (HC) was below the 5th centile at the routine second-trimester scan. Materials and Methods We retrospectively analysed outcomes of 18 377 women according to HC Z scores at second-trimester ultrasound examination between 2001 and 2008. We collected all major malformations, intrauterine deaths and other abnormal outcomes. Results Six hundred seventy-four fetuses (3.7%) had an HC below the 5th centile. Twenty-one major malformations were noted, consisting mainly of neurological abnormalities (3.1%). There were seven intra uterine fetal death (1.3%). Of all the fetuses, 26% were lost to follow-up. Outcome and neurological development was normal in 467 cases, based on neonatal examination and/or parent or general practitioner reports. Major abnormalities were noted in respectively 26.2%, 3.0% and 1.1% of fetuses with Z scores