Obesity's impact on intrapartum electronic fetal monitoring

The objective of this study is to evaluate the impact maternal obesity has on the percentage of unmonitored electronic fetal monitoring (EFM).

Women undergoing induction of labor at term were categorized into three groups: Group 1 (body mass index (BMI) < 30 kg/m²), Group 2 (30 < BMI < 40 kg/m²), and Group 3 (BMI ≥ 40 kg/m²). External EFM tracings were reviewed from the time of induction of labor until amniotomy; the percentage of time off of EFM was calculated. Statistical analysis was performed using commercially available software.

Three hundred and thirty-seven patients were stratified into the following groups: 104 patients in Group 1, 156 patients in Group 2, and 77 in Group 3. No significant differences were found between groups when analyzed for gestational age, bishop score, parity, race, and 5 min APGAR less than 7 or admission to the NICU. The mean percentage unmonitored by EFM was 5% for Group 1, 7% for Group 2 and 11% for Group 3. There was a significant association between percent of time unmonitored by EFM and BMI (r = 0.344 p < .0001).

At term gestation, the fetuses of obese women spend more time unmonitored by external intrapartum EFM than non-obese women. This represents a disparity among a high-risk group that may result in poor pregnancy outcomes if fetal distress is present.