Buhimschi Catalin S, Buhimschi Irina A, Malinow Andrew M, Weiner Carl P
Department of Obstetrics, Gynecology and Reproductive Sciences, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06510, USA.
Obstet Gynecol. 2004 Feb;103(2):225-30. doi: 10.1097/01.AOG.0000102706.84063.C7.
The perception that obese women have longer labors and a higher frequency of operative delivery because they are "poor pushers" persists despite the absence of objective study. We tested the hypothesis that obese women generate inadequate intrauterine pressure during the second stage of labor.
Intrauterine pressure was prospectively measured in 71 women during the second stage of labor. Obesity was defined as a body mass index (BMI) greater than 29 (n = 17). A BMI below 25 was normal (n = 40). Women with a BMI between 26 and 29 (n = 14) were considered overweight. All women labored with epidural analgesia and were alert and responsive throughout the study. After recording the baseline contractility, a standardized Valsalva maneuver was performed during contractions. The area under the intrauterine pressure curve (integral) was used as an estimate of uterine contractility.
All women delivered vaginally. There were no significant differences in baseline uterine contractility among obese, overweight, and normal women either before (obese 1,787 mm Hg/s; 95% confidence interval [CI] 1,164, 2,742 versus normal 1,569 mm Hg/s; 95% CI 718, 2,371 versus overweight 1,770 mm Hg/s; 95% CI 1,305, 2,835; P =.223) or during Valsalva maneuver (obese 2,831 mm Hg/s; 95% CI 1,771, 4,599 versus normal 2,637 mm Hg/s; 95% CI 1,240, 4,390 versus overweight 2,813 mm Hg/s; 95% CI 1,209, 4,982; P =.742). A BMI greater than 25 was associated with a higher frequency of oxytocin augmentation (P =.037). Univariate analysis revealed a relationship between labor duration and BMI (r = 0.299, P =.018). Obese women labored longer during the active phase (one-way analysis of variance, P =.02), but second-stage duration was similar among groups (one-way analysis of variance P =.44). Obesity did not increase the incidence of perineal lacerations (P =.82) or frequency of operative delivery (relative risk obese versus nonobese = 0.212; 95% CI 0.04, 1.05).
Obese women produce second-stage intrauterine pressures equivalent to women with a normal BMI, although they may require oxytocin augmentation more often.
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尽管缺乏客观研究，但认为肥胖女性因“用力不佳”导致产程延长和手术分娩频率较高的观念依然存在。我们检验了肥胖女性在第二产程中子宫内压力不足的假设。
前瞻性地测量了71名女性在第二产程中的子宫内压力。肥胖定义为体重指数（BMI）大于29（n = 17）。BMI低于25为正常（n = 40）。BMI在26至29之间的女性（n = 14）被视为超重。所有女性均采用硬膜外镇痛分娩，且在整个研究过程中意识清醒、反应灵敏。记录基线收缩力后，在宫缩期间进行标准化的瓦尔萨尔瓦动作。子宫内压力曲线下的面积（积分）用作子宫收缩力的估计值。
所有女性均经阴道分娩。肥胖、超重和正常女性在基线子宫收缩力方面，无论是在（肥胖组1,787 mmHg/s；95%置信区间[CI] 1,164, 2,742，正常组1,569 mmHg/s；95% CI 718, 2,371，超重组1,770 mmHg/s；95% CI 1,305, 2,835；P = 0.223）还是在瓦尔萨尔瓦动作期间（肥胖组2,831 mmHg/s；95% CI 1,771, 4,599，正常组2,637 mmHg/s；95% CI 1,240, 4,390，超重组2,813 mmHg/s；95% CI 1,209, 4,982；P = 0.742）均无显著差异。BMI大于25与催产素加强使用频率较高相关（P = 0.037）。单因素分析显示产程与BMI之间存在关联（r = 0.299，P = 0.018）。肥胖女性在活跃期产程较长（单因素方差分析，P = 0.02），但各组间第二产程持续时间相似（单因素方差分析P = 0.44）。肥胖并未增加会阴裂伤的发生率（P = 0.82）或手术分娩的频率（肥胖组与非肥胖组的相对风险 = 0.212；95% CI 0.04, 1.05）。
肥胖女性在第二产程中产生的子宫内压力与BMI正常的女性相当，尽管她们可能更常需要使用催产素加强宫缩。
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