Detection of fetal growth restriction in patients with chronic hypertension: is it feasible?

To determine the utility of sonographic estimated fetal weight (EFW) in diagnosing intrauterine growth restriction (IUGR, birth weight < 10% for gestational age) in patients with chronic hypertension.

All pregnant patients with hypertension delivered during a 5-year period at three centers were identified retrospectively. Patients with gestational hypertension, pre-eclampsia, diabetes mellitus, fetal anomalies and absence of a sonographic examination within 3 weeks of delivery were excluded. Likelihood ratio (LR) and guidelines established by the Evidence-Based Medicine Working Group were used to determine whether sonographic EFW is a reliable diagnostic test to detect IUGR.

At the three centers, there were 264 patients with chronic hypertension (122, 77 and 65 at centers I, II and III, respectively). The incidence of IUGR ranged from 13% to 27% but was similar at the three locations (p = 0.064). The LR (with 95% confidence interval (CI)) of detecting IUGR was 4.4 (95% CI 2.5, 7.7), 2.3 (95% CI 1.4, 3.7) and 6.1 (95% CI 2.7, 13.7) at centers I, II and III, respectively. Based on the proportions of abnormal growth, we required 253 and 71 newborns with fetal growth restriction at centers I and II, respectively, to have narrow confidence intervals around the clinically important LR of 10. The extremely low incidence of IUGR at center III (13%) precluded the estimation of required sample size.

Use of Evidence-Based Medicine Working Group guidelines indicates that sonographic EFW is slightly to moderately useful in detecting fetal growth restriction in patients with chronic hypertension.