To assess whether non-elective caesarean section due to obstructed labour and/or ineffective uterine contractility was associated with maternal body mass index (BMI).
The prospective dataset from the Swedish Medical Birth Registry consisted of 233,887 nulliparous women with a spontaneous onset of labour categorized in six classes of pre-pregnancy BMI, who delivered in Sweden between, January 1, 1999 and December 31, 2005. The mode of delivery was classified as either vaginal or by caesarean section. The caesarean section was classified as either elective or non-elective. Adjusted risks for non-elective caesarean section due to ineffective uterine contractility, or obstructed labour or fetal distress were determined using Mantel-Haenszel technique.
The risk of a non-elective caesarean section due to obstructed labour was not significantly associated with maternal BMI. However, ineffective uterine contractility was significantly associated with maternal BMI and the risk of non-elective caesarean delivery due to labour arrest disorders increased with increasing BMI, reaching a 4-fold increased risk among the morbidly obese women. The risk of non-elective caesarean section due to fetal distress also increased significantly with increasing maternal BMI.
It appears that ineffective labour could be a factor leading to the increased risk of non-elective caesarean section among obese and morbidly obese women. These findings challenge obstetricians to learn more about how to manage oxytocin infusions during labour in relation to maternal BMI.
"When we examined around 4000 labor outcomes stratified by BMI, we found that the reason for the emergency CS was the significantly increased risk of failure to progress in the first stage of labor, which is also known as dysfunctional labor . A subsequent analysis of more than 230,000 Swedish births also concluded that ineffective labor is a key factor leading to the increased risk of CS among obese women, and found no evidence that obstruction was acause. Slow progress of labor is now accepted as the most common cause of unplanned CS in obese women. "
"A wide variety of perinatal complications are associated with maternal obesity including prolonged pregnancy, less likelihood of spontaneous onset of labour at term, slower cervical dilation, longer duration of labour and an increased risk of intrapartum caesarean delivery [2,3]. Increased maternal body mass index (BMI) has also been significantly associated with ineffective uterine contractility , and the reasons for this are complex, and have been linked to elevated cholesterol levels (6) and a reduction in intracellular free calcium [Ca(2+)] flux in previous reports . These findings suggest a possible dysregulation in myometrial contractility pathways occurs in association with maternal obesity, but there are minimal data to clearly support this hypothesis or explain the potential mechanisms. "
[Show abstract][Hide abstract] ABSTRACT: Obesity is becoming an increasing problem in obstetric practice; it has led to an increase in the risk of caesarean delivery, prolonged pregnancy and dysfunctional labour. It has been postulated that many of these problems are as a result of abnormal myometrial contractility. The RhoA/Rho kinase pathway is involved in calcium sensitisation in the myometrium during labour and contributes to the phosphorylation of myosin phosphatase and thus continued myosin light chain activity, during uterine contractility. The aim of this study therefore, was to investigate the effect of obesity on the expression of various components of the RhoA/ROCK pathway in human myometrium at term pregnancy.
Protein was isolated from myometrial biopsies obtained at elective caesarean section, at term pregnancy from obese women and from those with a normal body mass index. Western blotting was performed using specific primary antibodies to RhoA/ Rho kinase associated proteins.
The protein expression of p160 ROCK-1 was significantly decreased (P < 0.001) in the myometrium from women in the obese cohort (n = 22) at term pregnancy, compared to women of those of normal body mass index (n = 15). No alteration in expression of the other proteins investigated was noted.
The significant decrease in p160 ROCK-1 protein expression observed in the myometrium of obese women at late gestation may contribute to an inhibitory effect on contractility at labour, due to its contribution to calcium sensitisation and possibly other signalling pathways. These findings are relevant to the concept of compromised myometrial function in obese parturients.
"Non-elective caesarean childbirth due to ineffective contractility was significantly more frequent in obese women compared to normal weight women. Moreover, the risk for non-elective caesarean childbirth due to labour arrest disorders increased with increasing BMI, reaching a 4-fold increase among the morbidly obese women (Zhang et al., 2007; Cedergren, 2009) (Table 2). After adjusting for the effects of birth weight, the increased risk of caesarean section in obese women remained. "
[Show abstract][Hide abstract] ABSTRACT: BACKGROUND: the incidence of obesity increases in all developed countries to frightful percentages, also in women of reproductive age. Maternal obesity is associated with important obstetrical complications; and this group also exhibits a higher incidence of prolonged pregnancies and labours. OBJECTIVE: to review the literature on the pathophysiology of onset and progression of labour in obese woman and translate this knowledge into practical recommendations for clinical management. METHODS: a literature review, in particular a critical summary of research, in order to determine associations, gaps or inconsistencies in this specific but limited body of research. FINDINGS: the combination of a higher incidence of post-term childbirths and increased inadequate contraction pattern during the first stage of labour suggests an influence of obesity on myometrial activity. A pathophysiologic pathway for altered onset and progression of labour in obese pregnant women is proposed. CONCLUSIONS: analysis of the literature shows that obesity is associated with an increased duration of pregnancy and prolonged duration of first stage of labour. IMPLICATIONS FOR PRACTICE: an adapted clinical approach is suggested in these patients.
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