Increasing Maternal Body Mass Index and Characteristics of the Second Stage of Labor

Abstract

Objective To evaluate the length of the second stage of labor in relation to increasing maternal prepregnancy BMI among nulliparous parturients, and to determine whether route of delivery differs among obese, overweight, and normal weight women reaching the second stage. Methods We performed a secondary analysis of a multicenter trial of fetal pulse oximetry, conducted among 5,341 nulliparas who were induced or labored spontaneously at 36 weeks or more of gestation. Normal weight was defined as BMI of 18.5-24.9 kg/m2, overweight was a BMI of 25.0-29.9 kg/m2, and obese was a BMI of 30 kg/m2 or higher. Results Of the 5,341 women, 97% had prepregnancy BMI recorded. Of these, 3,739 had a BMI 18.5 kg/m2 or higher and reached the second stage of labor. Increasing maternal BMI was not associated with second stage duration: normal weight 1.1 hr, overweight 1.1 hr, and obese 1.0 hr (p=0.13) . Among women who reached the second stage, as BMI increased, so did the likelihood that the woman had undergone induction of labor. Even so, the lack of association between second-stage duration and BMI did not vary by method of labor onset (p=0.84). The rate of cesarean delivery in the second stage did not differ by increasing BMI: normal weight 7.1%, overweight 9.6%, obese 6.9% (p=0.17). Conclusion Among nulliparous women who reach the second stage of labor, increasing maternal BMI is not associated with a longer second stage or an increased risk for cesarean delivery.

Intrapartum Management of the Obese Gravida

“…E-mail: jruthcarpenter@gmail.com labor found that median first-trimester BMI (kg/m 2 ) was higher among those women who delivered postdates compared with those that delivered at term (23.4 vs. 22.9, P<0.0001). When the study sample was expanded to include women with IOL or CD before labor, there was a doseresponse relationship between increased first-trimester BMI and decreased odds of spontaneous labor at term [BMI = 20 to <24.9: reference; BMI = 25 to <29.9: odds ratio (OR) = 0.71; 95% confidence interval (CI), 0.69-0.74; BMI = 30 to <34.9: OR = 0.57; 95% CI, 0.54-0.60; BMIZ35: OR = 0.43; 95% CI, 0.40-0.47].…”

“…In a secondary analysis of >5000 women enrolled in an NIH study of fetal pulse oximetry, maternal BMI was not associated with duration of the second stage of labor, despite the fact that obese women who reached the second stage were significantly more likely to have undergone an IOL. 22 The Consortium on Safe Labor found that length of the second stage of labor was similar among BMI categories for nulliparous women but was decreased as BMI increased among multiparous women. 13 Another study found that obese women in the second stage have equivalent baseline uterine contractility and are able to generate equivalent intrauterine pressures with Valsalva as normal-weight women (despite a longer active phase and higher frequency of oxytocin augmentation).…”

Labor length among overweight and obese women undergoing induction of labor

“…Additionally, Ob nulliparous women have a significantly increased rate of cesarean delivery [6]. Several studies, however, have demonstrated no association between maternal BMI and length of the second stage in nulliparous women [11,15,16], suggesting that it is not the second stage of labor, but rather the first stage, that may be most affected by increasing maternal weight in nulliparas.…”

Influencia de la obesidad en la evolución del parto

“…Con respecto a los partos instrumentales, nuestro estudio mostró que son similares en el grupo control y en el de gestantes con obesidad mórbida; esto reafirma la teoría (ya expuesta en otros artículos, como los publicados por Vahratian et al 15 , Buhimschi et al 16 o Kominiarek et al 17 , de que la obesidad hace prolongar la primera parte del parto (fase de dilatación), pero no la segunda (periodo de expulsivo) [15][16][17][18][19][20][21] .…”

“…Entre ellas podemos destacar que la obesidad hace prolongar la primera parte del parto (fase de dilatación) [15][16][17][18][19][20][21] , pero no la segunda (periodo de expulsivo), dato que debemos tener en cuenta si nos enfrentamos al parto de una mujer con obesidad. Por otra parte, la inducción es más frecuente en mujeres obesas que en no obesas 9,12,22-26 , siendo además la tasa de fallo de inducción más frecuente 26 .…”