- Acta Obstet Gynecol Scand 2003; 82: 22–27. © Acta Obstet Gynecol Scand 2003 Background. Elevated mid-trimester human chorionic gonadotropin (hCG) is associated with adverse maternal and perinatal outcome. The aims of the study were to evaluate the association between elevated hCG, fetal pathological arterial waveforms and maternal and perinatal complications. Methods. Pulsatility indices (PI) of middle cerebral artery (MCA) and umbilical artery (UA) were determined prospectively in 121 consecutive patients with abnormal maternal serum hCG (> 2.5 MoM). Each patient had four US scans during pregnancy. Patients with known structural or chromosomal anomalies were excluded. Results. Of 121 women with hCG > 2.5 MoM, 36/121(29.6%) had hCG between 2.5 and 3.0 MoM, 35/121(28.9%) had hCG between 3.0 and 3.5 MoM, 21/121(17.3%) had hCG of 3.5–4.0 MoM, 17/121(14.1%) had hCG levels between 4.0 and 4.5 MoM, and 12/121(9.9%) had hCG > 4.5 MoM. Middle cerebral artery PI was significantly lower in women with hCG > 4.0 MoM between 28 and 36 weeks' gestation, but not between 18 and 27 weeks' gestation. No differences of MCA PI were found when the cut-off point of hCG was 3.5. Women with hCG levels > 4.0 MoM had a significantly higher rate of preterm deliveries, cesarean sections, higher rate of Apgar scores < 7 and a significantly lower mean birth weight in comparison with women with hCG < 4.0 MoM. The prevalence of PIH and preeclampsia and perinatal death were found to be higher among patients with hCG levels > 4.0 MoM, although not significantly. No differences were found at hCG levels less than 4.0 MoM. Conclusions. In pregnancies with mid-trimester hCG > 4.0 MoM, redistribution of cerebral blood flow is expressed after 28 weeks' gestation. These pregnancies have higher rates of maternal and neonatal complications as compared to pregnancies with lower hCG levels.