There is an obesity pandemic in the United States. In 1991, approximately 12% of the US population was obese,1 and no single state had an obesity rate greater than 15%. In 2014, the obesity rate was 38%,2 and no single state had an obesity rate less than 20%. Assuming that the prevalence of obesity was nearly zero for much of human history, it took thousands of years to reach an obesity prevalence of about 15%, but then just 25 years to more than double that rate. This pandemic is not only in the United States. Obesity rates have increased across most developed countries. Canada, for example, has had a similar increase in obesity, with prevalence reaching 24% among reproductive-aged women in 2012.3 Even in low-and middle-income countries, obesity rates are increasing.4 Health care costs associated with obesity are substantial. According to a 2013 report, obesity was estimated to add $600 per year in health care costs for a 20-year-old and $3800 per year in health care costs for a 70-year-old.5 According to these estimates, it is conceivable that health care costs associated with obesity could be more than $300 billion per year in the United States. In 2014, approximately 50% of all pregnant women in the United States were overweight or obese.6 Obese pregnant women are at increased risk of pregnancy complications. Maternal-related pregnancy complications (diabetes, preeclampsia, and cesarean delivery) and fetal or neonatal complications (preterm birth, macrosomia, fetal growth restriction, and stillbirth) are more common in obese pregnant women. Further, some evidence suggests that the recent increase in maternal mortality in the United States is related to maternal obesity.7 However, the causal pathway between obesity and maternal mortality is unclear. Are obese pregnant women at greater risk for comorbid events that lead to mortality, or are clinicians less able to adequately manage such events because of the obesity? In one study, the risks of low Apgar scores and neonatal intensive care unit admissions among newborns were 50% greater after a uterine rupture in obese pregnant women compared with nonobese pregnant women, presumably because of the surgical challenges with obese women.8 One approach to understanding reasons for the increasing mortality rates in obese pregnant women is to establish associations of obesity with severe maternal morbidity in pregnancy, because severe maternal morbidity may precede and contribute to increased mortality rates in obese pregnant women. In this issue of JAMA, Lisonkova and colleagues9 examine the association between prepregnancy body mass index (BMI) and severe maternal morbidity. The authors designed a population-based retrospective cohort study over a 10-year period (2004-2013) in Washington State using linked vital statistics and hospital discharge data. They examined BMI categories of underweight, normal weight, overweight, and obese (BMI >30), and further subcategorized obesity into class 1 (30-34.9), class 2 (35-39.9), and class 3 (≥40), allowing a more detailed examination of a dose-response relationship. Severe maternal morbidity was identified using International Classification of Diseases, Ninth Revision and Current Procedural Terminology codes as defined by the Canadian Perinatal Surveillance System and the Centers for Disease Control and Prevention. Conditions constituting severe maternal morbidity included sepsis, shock, cardiovascular events, cerebrovascular events, acute renal failure, and other similarly severe medical and surgical complications. The study population included 743 630 women, with prepregnancy BMI categorized as follows: underweight, 3.2%; normal weight, 47.5%; overweight, 25.8%; obesity class 1, 13.1%; obesity class 2, 6.2%; and obesity class 3, 4.2%. For the composite outcome of severe maternal morbidity, there were statistically significant increases in risk of severe maternal morbidity among women with class 1 obesity (absolute rate, 167.9 per 10 000; adjusted odds ratio [OR], 1.1 [95% CI, 1.1-1.2]), women with class 2 obesity (absolute rate, 178.3 per 10 000; adjusted OR, 1.2 [95% CI, 1.1-1.3]), and women with class 3 obesity (absolute rate, 202.9 per 10 000; adjusted OR, 1.4 [95% CI, 1.3-1.5]) compared with women who had prepregnancy BMIs in the normal range (absolute rate, 143.2 per 10 000). When specific outcomes were examined, transfusion for postpartum hemorrhage was lower among the obese women compared with those with normal BMI. Most of the other outcomes, including cardiovascular morbidity, cerebrovascular events, sepsis, and acute renal failure, were increased, with the largest risks among pregnant women with class 3 obesity. These findings support the hypothesis that the association of class 3 obesity with increased severe maternal morbidity in pregnancy may contribute to an increased risk of maternal mortality in those women. Additionally, identifying women at increased risk for complications may enable clinicians to reduce their risk of morbidity. For example, in one study of a Maternal Early Warning Trigger tool that examined maternal characteristics to identify women at increased risk of severe complications in labor and delivery, the authors reported a reduction in severe maternal morbidity.10 Perhaps if class 3 obesity were added to these Related article page 1777 Opinion

中文翻译：

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孕前肥胖和严重的孕产妇发病率

美国有肥胖流行病。1991 年，大约 12% 的美国人口肥胖，1 并且没有一个州的肥胖率超过 15%。2014 年，肥胖率为 38%，2 且没有一个州的肥胖率低于 20%。假设在人类历史的大部分时间里，肥胖的流行率几乎为零，那么肥胖流行率达到约 15% 需要数千年的时间，但仅用了 25 年就超过了两倍。这种流行病不仅发生在美国。大多数发达国家的肥胖率都有所增加。例如，加拿大的肥胖率也有类似的增加，2012 年育龄妇女的患病率达到 24%。3 即使在低收入和中等收入国家，肥胖率也在增加。4 与肥胖相关的医疗保健费用很高。根据 2013 年的一份报告，肥胖估计会使 20 岁的人每年增加 600 美元的医疗保健费用，而 70 岁的人每年增加 3800 美元的医疗保健费用。 5 根据这些估计，可以想象在美国，与肥胖相关的医疗保健费用每年可能超过 3000 亿美元。2014 年，美国约有 50% 的孕妇超重或肥胖。6 肥胖孕妇出现妊娠并发症的风险增加。孕产妇相关妊娠并发症（糖尿病、先兆子痫和剖宫产）和胎儿或新生儿并发症（早产、巨大儿、胎儿生长受限和死产）在肥胖孕妇中更为常见。更多，一些证据表明，最近美国孕产妇死亡率的上升与孕产妇肥胖有关。7 然而，肥胖与孕产妇死亡率之间的因果关系尚不清楚。肥胖孕妇是否更容易发生导致死亡的共病事件，或者临床医生是否因为肥胖而无法充分管理此类事件？在一项研究中，与非肥胖孕妇相比，肥胖孕妇在子宫破裂后出现低 Apgar 评分和新生儿重症监护病房的风险要高 50%，这可能是因为肥胖妇女面临手术挑战。 8理解肥胖孕妇死亡率上升的原因是建立肥胖与妊娠期严重孕产妇发病率之间的关联，因为严重的孕产妇发病率可能先于并导致肥胖孕妇死亡率的增加。在本期 JAMA 中，Lisonkova 及其同事 9 研究了孕前体重指数 (BMI) 与严重孕产妇发病率之间的关联。作者使用相关的生命统计数据和出院数据，在华盛顿州设计了一项为期 10 年（2004-2013 年）的基于人群的回顾性队列研究。他们检查了体重不足、正常体重、超重和肥胖 (BMI >30) 的 BMI 类别，并将肥胖进一步细分为 1 级 (30-34.9)、2 级 (35-39.9) 和 3 级 (≥40)，允许对剂量反应关系的更详细检查。使用国际疾病分类确定了严重的孕产妇发病率，由加拿大围产期监测系统和疾病控制和预防中心定义的第九次修订和当前程序术语代码。构成严重孕产妇发病率的条件包括败血症、休克、心血管事件、脑血管事件、急性肾功能衰竭和其他类似的严重内科和外科并发症。研究人群包括 743 630 名女性，孕前 BMI 分类如下：体重不足，3.2%；正常体重，47.5%；超重，25.8%；肥胖 1 级，13.1%；肥胖 2 级，6.2%；和肥胖 3 级，4.2%。对于重度孕产妇发病率的复合结局，1 级肥胖女性患重度孕产妇发病率的风险在统计学上显着增加（绝对率，167.9/10000；调整后的比值比 [OR]，1.1 [95% CI，1.1- 1.2]），2 级肥胖女性（绝对率，178.3/10000；调整后 OR，1.2 [95% CI，1.1-1.3]）和 3 级肥胖女性（绝对率，202.9/10000；调整 OR，1.4 [95] % CI，1.3-1.5]）与孕前 BMI 在正常范围内的女性（绝对比率，143.2/10 000）相比。当检查特定结果时，与体重指数正常的女性相比，肥胖女性因产后出血而输血的比例较低。大多数其他结果，包括心血管发病率、脑血管事件、败血症和急性肾功能衰竭，都增加了，其中 3 级肥胖孕妇的风险最大。这些发现支持了这样的假设，即 3 类肥胖与孕期严重孕产妇发病率增加之间的关联可能会导致这些女性孕产妇死亡风险的增加。此外，识别出并发症风险增加的女性可以使临床医生降低发病风险。例如，在一项针对孕产妇早期预警触发工具的研究中，该工具检查了孕产妇的特征，以确定在分娩过程中出现严重并发症风险增加的妇女，作者报告说孕产妇的严重发病率有所降低。 10 也许如果将 3 类肥胖添加到这些相关文章第1777页意见