A simple model to predict the internal rotation
A total of
257(77.6%)
women with a fetus in non-OA position during the latent phase underwent
spontaneous rotation to OA position before delivery; however, 74
(22.4%) were persistent OP or OT position. According to the occurrence
of internal fetal head rotation, the individual characteristics were
similar besides maternal height (161.0±4.4 vs. 159.7±5.2 cm; P = 0.022)
(Table S2). The multivariable logistic regression analysis demonstrated
that the MLA (adjusted odds ratio [aOR]: 1.021, 95% confidence
interval [CI]:1.008-1.034) and maternal height (aOR: 1.107, 95%
CI:1.026-1.195) were the significant predictors of spontaneous fetal
occiput rotation after adjusting
for maternal age, gestational age, overweight, premature rupture of the
membrane, labor induction, oxytocin augmentation and the use of epidural
analgesia (Table S3). The final model that predicted internal fetal head
rotation based on MLA at the first ultrasound scan and the maternal
height was shown in Table 3, which obtained the AUC was 0.667 (95% CI,
0.583-0.751; P<0.001) (Figure 2). The calibration curve shows
good agreement between predicted and observed probabilities for the
occurrence of spontaneous fetal head rotation (Figure 3(a)).