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作者：Barbara Boughton  
出處：WebMD醫學新聞

　　May 28, 2010 (加州舊金山) — 根據研究者在美國婦產科研討會第58屆年度科學會議中的報告，過重與肥胖的青少女比正常體重的同儕更可能從事有風險的性行為。
　　
　　當研究者分析疾病管制中心(CDC)「Youth Risk Behavior Study」這項研究的資料時，他們發現，肥胖與過重青少女比較可能在13歲前有性行為，且有3個以上的終身性伴侶，比較不會使用保險套或避孕。
　　
　　第一作者、Margaret Villers醫師和南卡羅來納醫學大學的研究夥伴表示，之前的研究顯示，肥胖與不佳體態有關，而自尊不佳和高風險性行為有關，因此提出假設，過重女性可能比較會參與有風險的性行為。Villers醫師表示，因為美國的肥胖比率上升，我認為，對這個日益增加的人口統計學現象多加瞭解很重要。
　　
　　研究者使用CDC在2003至2007年間的「Youth Risk Behavior Study」這項研究的資料，分析21,773名正常體重、過重與肥胖青少女的趨勢。Villers醫師指出，「Youth Risk Behavior Study」這項研究每兩年進行一次，對象是9 -12年級的學生，提供一個具美國全國代表性的樣本。使用自我報告的體重和身高計算身體質量指數，使用CDC的準則，根據性別和年紀定義過重與肥胖。
　　
　　研究者評估6種不同的風險性行為，包括是否在十幾歲就有性行為、第一次性行為的年紀、性伴侶的數量。他們也評估這些青少年在最近的性行為時，有無使用酒精或藥物、是否有使用保險套或者任何的避孕方法。
　　
　　當研究者分析不同種族的資料時，他們發現，黑人和西班牙裔女性最可能過重或肥胖(P< .001)，不過，在過重和肥胖女性中，不論年紀或年級，種族似乎和風險性行為無關。
　　
　　他們的發現顯示，過重或肥胖不會影響青少年的性行為史、也不會影響他們最後發生性行為時有無使用酒精或藥物。
　　
　　相較於正常體重者，肥胖女孩(勝算比[OR]為2.6)和過重女孩(OR，1.6)最容易在13歲前發生第一次性行為。相較於體重正常的同儕，過重和肥胖女性有30%更可能有超過3個終身性伴侶(OR，1.3)，有20%比較不可能使用保險套(肥胖女孩之OR為0.81；過重女孩之OR為0.82)。相較於正常體重的青少女，在最近的性行為中，過重女孩有30%、肥胖女孩有40%比較不可能使用任何型式的避孕法(OR分別是0.67和0.61)。
　　
　　Villers醫師指出，這個研究有許多限制，包括這些青少年可能不知道他們的體重、或者低估或高估體重。不過，其他研究曾經發現，青少年對自己的體重估計是可信的。她也指出，青少年可能會過度強調自己的性經驗，不過其他針對青少年性行為的調查顯示，和「Youth Risk Behavior Study」這項研究的反應相當。
　　
　　Villers醫師表示，研究者未分析的一個重要干擾因素是社會經濟狀態。
　　
　　她表示，在我們的研究中，雖然肥胖和過重比種族更可以預測高風險行為，高風險行為並未隨著體重增加而增加。不論是過重或肥胖的青少女，其高風險性行為的機率相當。
　　
　　Villers醫師表示，該研究的影響是，過重和肥胖青少女可能從事高風險性行為，這將讓她們處於性病和意外懷孕的風險。我們需要更加瞭解何以這些青少年藉由高風險性行為來改善認同作用，也要探討對這些高風險青少年的介入方式。
　　
　　布朗大學、羅德島婦嬰醫院婦產科助理教授Sarah Fox醫師表示，很少有研究探討青少年過重或肥胖與高風險行為之間的關聯，大多是探討成人體重對高風險性行為的影響。
　　
　　Fox醫師表示，此篇研究的資料品質高，因為他們使用「Youth Risk Behavior Study」這項研究，那是相當大的資料來源，不過，對醫師而言，多瞭解這些青少年的絕對風險、以及他們從事有風險性行為的可能性將會更有幫助。
　　
　　她指出，過重和肥胖青少年在傳統上不被認為是會發生有風險性行為的一群。每個人都要知道安全性行為，但是，性教育計畫和公共衛生部門，更應將過重或肥胖青少年容易發生有風險的性行為謹記在心。
　　
　　Fox醫師同意Villers醫師的看法，後續研究應聚焦在為何過重和肥胖青少女比正常體重者更可能從事有風險的性行為。她表示，然後，我們可以選擇有助於這些年輕人做出更健康選擇的介入方式。
　　
　　Villers醫師與 Fox醫師皆宣告沒有相關財務關係。
　　
　　美國婦產科研討會(ACOG)第58屆年度科學會議。發表於2010年5月17日。


Obesity a Factor in High-Risk Sexual Behavior in Adolescent Girls

By Barbara Boughton
Medscape Medical News

May 28, 2010 (San Francisco, California) — Overweight and obese adolescent girls are more likely to engage in risky sexual behavior than their normal-weight peers, according to researchers here at the American Congress of Obstetricians and Gynecologists 58th Annual Clinical Meeting.

When researchers analyzed data from the Centers for Disease Control and Prevention (CDC) Youth Risk Behavior Study, they found that obese and overweight adolescent girls were more likely to have sex before the age of 13 years and to have more than 3 lifetime partners, and were less likely to use condoms or contraception.

Previous studies have shown that obesity is related to poor body image, and poor self-esteem is associated with high-risk sexual behavior, leading Margaret Villers, MD, and colleagues from the Medical University of South Carolina in Charleston, to hypothesize that overweight females might be more likely to participate in risky sexual behavior. "Due to the rising rate of teen obesity in the United States, I think it's important to understand more about this rising demographic," Dr. Villers said.

The researchers used data from the CDC's Youth Risk Behavior Survey from 2003 to 2007 to analyze trends in 21,773 normal-weight, overweight, and obese adolescent girls. The Youth Risk Behavior Study is administered every 2 years to students in grades?9 to 12, and provides a nationally representative sample from the United States, Dr. Villers noted. Body mass index is calculated using self-reported weight and height, and CDC criteria are used for definitions of overweight and obese by age and sex.

The researchers evaluated 6 different risky sexual behaviors, including whether or not the teens had sexual intercourse, the age at which they first had sexual intercourse, and the number of sexual partners. They also assessed behaviors such as use of alcohol or drugs during the teens' last sexual encounter, and if they had used a condom or any form of contraception during their last sexual intercourse.

When the researchers analyzed data from different racial and ethnic groups, they found that black and Hispanic females were the most likely to be overweight or obese (P?< .001). However, race did not seem to play a part in risky sexual behavior among overweight and obese females, and neither did age or grade in school.

Their findings revealed that being overweight or obese did not affect the teens' history of sexual intercourse or whether or not they used alcohol or drugs when they last had sexual intercourse.

Sexual debut before 13 years was more likely among girls who were obese (odds ratio [OR], 2.6) and overweight (OR, 1.6) than among those who were normal weight. Overweight and obese females were 30% more likely to report more than 3 lifetime partners (OR, 1.3) and 20% less likely to use condoms than their normal-weight peers (OR for obese girls, 0.81; OR for overweight girls, 0.82). Overweight girls were 30% less likely and obese girls were 40% less likely to report any form of contraception at last intercourse than normal-weight adolescent girls (OR, 0.67 and 0.61, respectively.)

Dr. Villers noted that there were several limitations to the study, including the fact that adolescents might not know their weight or might under- or overestimate it. However, other studies have found that adolescents are reliable in their weight estimation. She also pointed out that adolescents might overemphasize their sexual experiences, although data from other surveys of sexual behavior in adolescents show responses that are equivalent to those in the Youth Risk Behavior Survey.

One important confounder that the researchers did not analyze was socioeconomic status, Dr. Villers said.

"While obesity and being overweight were more predictive of high-risk behavior in our study than race was, high-risk behaviors did not increase with increasing body weight," she said. The adolescent girls had approximately similar odds of high-risk sexual behavior whether they were overweight or obese.

The implications of the study are that overweight and obese adolescent females might be participating in high-risk sexual behavior that could put them at risk for sexually transmitted infections and unplanned pregnancies, Dr. Villers said. "We need a greater understanding of why these adolescents are pursuing high-risk sexual behaviors to improve identification and interventions for high-risk teens," she said.

The relation between being overweight or obese and high-risk behavior has rarely been studied in adolescents, said Sarah Fox, MD, assistant professor in obstetrics and gynecology at Women's and Infants Hospital of Rhode Island and Brown University in Providence. Studies on high-risk sexual behavior that considered weight have been in adults.

"The quality of the data in this study is high because they used the Youth Risk Behavior Survey; that's a really great information source. However, it might have been more helpful to clinicians to know these teens' absolute risk, as well as their odds for sexually risky behaviors," Dr. Fox said.

She noted that overweight and obese adolescents have not traditionally been recognized as a group with a high likelihood of risky sexual behavior. "Everyone needs to know about safe sex, but being overweight or obese during the teenage years may be a sexual risk behavior that may be important to keep in mind for sex education programs and public health," she said.

Dr. Fox agreed with Dr. Villers that future research needs to focus on the reasons why overweight and obese adolescent girls are more likely to engage in sexually risky behaviors than those who are normal weight. "Then we might be able to choose interventions that can help these young people make more healthy choices," she said.

Dr. Villers and Dr. Fox have disclosed no relevant financial relationships.

American Congress of Obstetricians and Gynecologists (ACOG) 58th Annual Clinical Meeting. Presented May?17, 2010.