Symphysis Fundus Measurements for Detection of Intrauterine Growth Retardation

Abstract: A case-control study was performed to evaluate the Swedish population-based symphysis fundus (SF) reference curves. The study included 242 small for gestational age (SGA) neonates (169 term and 73 preterm infants) as cases and 296 non-SGA infants as controls. Two Swedish SF curves were evaluated. In term pregnancies they showed a sensitivity of 32 % and 51 % and a specificity of 90 % and 83 %, respectively, at a cut-off level of < - 2 SD from the mean according to the SF reference curve. The sensitivity for SGA was higher in preterm pregnancies (49 % and 58 %, respectively) and the first alarm below – 2 SD was noted before 32 weeks in 37 % and 43 % of the preterm pregnancies, respectively. (Study I)A study of self-administered SF measurements was designed to achieve more regular and frequent SF measurements. Thirty-three women with singleton, ultrasound dated pregnancies performed SF measurements on average 14 weeks from gestational week 20 to 25 until delivery. Self-administered SF measurements were higher and had higher variance than midwives’ measurements. Four consecutive SF measurements on each occasion can compensate for higher variance. Reliable self-administered SF measurements can be obtained. (Study II)Self-administered SF measurements from 191 women were used to construct absolute and relative SF growth references. The influence of fetal sex, maternal obesity and parity was assessed in regression models. The lnSF growth was statistically influenced by maternal obesity, and a borderline significance was recorded for fetal sex and parity. Statistical analysis and graphical displays show no evidence that the relative lnSF growth should be dependent on these variables. (Study III)To improve detection of infants with intrauterine growth restriction (IUGR) rather than SGA a new statistical model (the SR method) was used. The SR method was evaluated with SF measurements from 1122 pregnant women. The sensitivity for neonatal morbidity and SGA was low, between 6 and 36 % for SGA (< -2SD). Neonates classified as SGA (< -2SD and < 10th percentile) had increased morbidity compared with the total study group. Neonates suspected to be SGA before delivery by the population-based SF measurement method had lower morbidity than those not suspected. The SR method was found not to improve detection of fetuses with increased morbidity or SGA neonates in this study. Better screening methods to detect IUGR and SGA prior to delivery are needed. (Study IV)