BACKGROUND & AIMS: PURPOSE:Consistent condom use is critical to efforts to prevent sexually transmitted infections among adolescents, but condom use may decline as relationships and contraceptive needs change. The purpose of this research is to assess changes in condom non-use longitudinally in the context of changes in relationship quality, coital frequency and hormonal contraceptive choice. METHODS:Participants were women (aged 14-17 years at enrollment) recruited from three urban adolescent medicine clinics. Data were collected at three-month intervals using a face-to-face structured interview. Participants were able to contribute up to 10 interviews, but on average contributed 4.2 interviews over the 27-month period. Independent variables assessed partner-specific relationship quality (five items; scale range 5-25; alpha = .92, e.g., this partner is a very important person to me); and, number of coital events with a specific partner. Additional items assessed experience with oral contraceptive pills (OCP) use and injected depo medroxy-progesterone acetate (DMPA). The outcome variable was number of coital events without condom use during the past three months. Analyses were conducted as a three-level hierarchical linear growth curve model using HLM 6. The Level 1 predictor was time, to test the hypothesis that condom non-use increases over time. Level 2 predictors assessed relationship quality and coital frequency across all partners to assess hypotheses that participants' condom non-use increases over time as a function of relationship quality and coital frequency. Level 3 predictors assessed the participant-level influence of OCP or DMPA experience on time-related changes in condom non-use. RESULTS:A total of 176 women reported 279 sex partners and contributed 478 visits. Both average coital frequency and average condom non-use linearly increased during the 27-month follow-up. At any given follow-up, about 35% reported recent OCP use, and 65% reported DMPA use. HLM analyses showed that condom non-use increased as a function of time (beta = .12; p = .03, Level 1 analysis). Increased condom non-use over time was primarily a function of increased coital frequency (beta = .01; p = .00), although higher levels of relationship quality were associated with increased condom non-use at enrollment (beta = .44; p = .00, Level 2 analysis). The temporal rise in condom non-use significantly increased among DMPA users (beta = .06; p = .00) but not OCP users (Level 3 analysis) (beta = -.04; p = .06). CONCLUSIONS:Developmentally, relationship characteristics and coital frequency appear to have increasing weight in decisions about condom use. Hormonal contraceptive methods are not equivalently associated with the overall temporal decline in condom use. Future research associated with dual contraceptive/condom use should address differential factors associated condom use in combination with different hormonal methods.

背景与目标：

BACKGROUND & AIMS: :Parents play an important role in the sexual health of their adolescent children. Based on previous research, formative research, and theories of behavioral change, we developed Talking Parents, Healthy Teens, an intervention designed to help parents improve communication with their adolescent children, promote healthy adolescent sexual development, and reduce adolescent sexual risk behaviors. We conduct the parenting program at worksites to facilitate recruitment and retention of participants. The program consists of 8 weekly 1-hour sessions during the lunch hour. In this article, we review the literature that identifies parental influences on adolescent sexual behavior, summarize our formative research, present the theoretical framework we used to develop Talking Parents, Healthy Teens, describe the program's components and intervention strategies, and offer recommendations based on our experiences developing the program. By targeting parents at their worksites, this program represents an innovative approach to promoting adolescent sexual health. This article is intended to be helpful to health educators and clinicians designing programs for parents, employers implementing health-related programs, and researchers who may consider designing and evaluating such worksite-based programs.

背景与目标： : 父母在青春期孩子的性健康中起着重要作用。基于先前的研究，形成性研究和行为改变理论，我们开发了会说话的父母，健康的青少年，这种干预措施旨在帮助父母改善与青春期孩子的沟通，促进健康的青春期性发展，并减少青春期的性风险行为。我们在工作场所开展育儿计划，以促进招募和留住参与者。该计划包括午餐时间每周8个1小时的课程。在本文中，我们回顾了确定父母对青少年性行为的影响的文献，总结了我们的形成性研究，提出了我们用来培养会说话的父母，健康的青少年的理论框架，描述了该计划的组成部分和干预策略，并根据我们的经验提供了建议开发该计划。通过针对工作场所的父母，该计划代表了一种促进青少年性健康的创新方法。本文旨在帮助健康教育者和临床医生为父母，实施健康相关计划的雇主以及可能考虑设计和评估此类基于工作现场的计划的研究人员设计计划。

BACKGROUND & AIMS: OBJECTIVES:This study assessed social and behavioural predictors for sexual risk taking and sexually transmitted infections (STIs) including HIV among adolescent female sex workers (FSWs) from Kunming, China. Additionally, health services needs and use were assessed. METHODS:A cross-sectional survey was conducted in 2010. Using snowball and convenience sampling, self-identified FSWs were recruited from four urban areas in Kunming. Women consenting to participate were administered a semi-structured questionnaire by trained interviewers identified from local peer-support organisations. Following interview, a gynaecological examination and biological sampling to identify potential STIs were undertaken. Descriptive and multivariable logistic regression analyses were performed. RESULTS:Adolescent FSWs had a mean age of 18.2 years and reported numerous non-paying sexual partners with very low rate of consistent condom use (22.2%). Half (50.3%) the respondents had sex while feeling drunk at least once in the past week, of whom 56.4% did not use condom protection. STI prevalence was high overall (30.4%) among this group. Younger age, early sexual debut, being isolated from schools and family, short duration in sex work, and use of illicit drugs were found to be strong predictors for unprotected sex and presence of an STI. Conversely, having access to condom promotion, free HIV counselling and testing, and peer education were associated with less unprotected sex. The majority reported a need for health knowledge, free condoms and low-cost STI diagnosis and treatment. CONCLUSIONS:There is an urgent need to improve coverage, accessibility and efficiency of existing interventions targeting adolescent FSWs.

背景与目标：

BACKGROUND & AIMS: :The present study utilized longitudinal data from a high-risk community sample (N = 377; 166 trauma-exposed; 202 males; 175 females; 73% non-Hispanic Caucasian) to test pretrauma measures of adolescent internalizing and externalizing symptoms as unique prospective predictors of type of trauma exposure and PTSD over and above the influence of correlated family adversity (a composite of family conflict, stress, and parental psychopathology). Data were analyzed with logistic and multinomial logistic regressions. Results indicated that females, but not males, with higher levels of internalizing (OR = 2.91) and externalizing (OR = 2.37) symptoms during adolescence were significantly more likely to be exposed to assaultive violence (over and above family adversity). In fact, males with higher levels of internalizing symptoms were significantly less likely to be exposed to assaultive violence (OR = 0.54). Neither internalizing nor externalizing symptoms uniquely predicted exposure to traumatic events that did not involve assaultive violence. Among trauma-exposed participants, the unique association between internalizing symptoms and later PTSD yielded an odds ratio of 1.79 (p = .07) over and above the influences of family adversity, type of trauma exposure, and gender. Assaultive violence exposure fully mediated the association between females' externalizing symptoms and future PTSD. Findings may help inform the prevention of both assaultive violence exposure and PTSD.

背景与目标： : 本研究利用了来自高风险社区样本的纵向数据 (N = 377; 166创伤暴露; 202男性; 175女性; 73% 非西班牙裔高加索人) 测试青少年内在化和外在化症状的创伤前措施，作为创伤暴露类型和创伤后应激障碍的独特前瞻性预测因子，超越相关家庭逆境 (家庭冲突、压力和父母心理病理学的组合) 的影响。数据采用logistic和多项logistic回归分析。结果表明，女性而不是男性，在青春期具有较高水平的内在化 (或 = 2.91) 和外在化 (或 = 2.37) 症状的女性更容易遭受攻击性暴力 (超过家庭逆境)。事实上，具有较高水平内化症状的男性暴露于攻击性暴力的可能性显著降低 (OR = 0.54)。内部化或外部化症状都不能唯一地预测暴露于不涉及攻击性暴力的创伤事件。在创伤暴露的参与者中，内在化症状与后来的PTSD之间的独特关联产生了1.79的优势比 (p = .07)，超出了家庭逆境，创伤暴露类型和性别的影响。攻击性暴力暴露充分介导了女性外在症状与未来创伤后应激障碍之间的关联。研究结果可能有助于预防攻击性暴力暴露和PTSD。

BACKGROUND & AIMS: :Iron deficiency and fatigue are common problems in adolescent females. Heavy menstrual bleeding (HMB) is associated with both iron deficiency and fatigue. The aim of this study was to define baseline ferritin values and fatigue symptoms in a population of young females with excessive menstrual blood loss, as compared to healthy controls. The study population included 11 to 17-year-old menstruating females presenting to an Adolescent Gynaecology Clinic, Menorrhagia Clinic or Sports Medicine clinic. To evaluate the degree and effects of menstrual blood loss, we utilized the Ruta Menorrhagia Severity Score. We investigated the symptoms of fatigue using the Fatigue Severity Scale. We evaluated possible predictors of ferritin level (age, body mass index, fatigue scores and Menorrhagia Severity Score) using generalized linear models. A total of 48 adolescents with HMB and 102 healthy adolescents completed the study. Iron deficiency and elevated fatigue scores were common findings in young women with HMB. Both fatigue severity scores and menorrhagia severity scores were significantly higher in young women with HMB as compared to healthy controls. In adolescents with HMB, 87.5% had ferritin levels ≤40 ng mL(-1), and 29.2% had ferritin levels ≤15 ng mL(-1). Our generalized linear models did not identify any significant univariate relationships between ferritin levels and patient age, body mass index, fatigue score or menorrhagia score. Iron deficiency and symptoms of fatigue are common findings in young women with HMB. Fatigue severity scores are significantly higher in young women with HMB as compared to healthy controls.

背景与目标： : 缺铁乏力是青春期女性的常见问题。大量月经出血 (HMB) 与铁缺乏和乏力有关。这项研究的目的是确定与健康对照组相比，月经失血过多的年轻女性人群的基线铁蛋白值和乏力症状。研究人群包括11至17岁的经期女性，这些女性在青春期妇科诊所，月经过多诊所或运动医学诊所就诊。为了评估月经失血的程度和影响，我们使用了Ruta月经过多严重程度评分。我们使用乏力严重程度量表调查乏力症状。我们使用广义线性模型评估了铁蛋白水平的可能预测因子 (年龄，体重指数，乏力评分和月经过多严重程度评分)。共有48名HMB青少年和102名健康青少年完成了这项研究。铁缺乏和乏力评分升高是HMB年轻女性的常见发现。与健康对照组相比，患有HMB的年轻女性乏力严重程度评分和月经过多严重程度评分均显着更高。在患有HMB的青少年中，87.5% 的铁蛋白水平 ≤ 40 ng mL(-1)，29.2% 的铁蛋白水平 ≤ 15 ng mL(-1)。我们的广义线性模型没有确定铁蛋白水平与患者年龄，体重指数，乏力评分或月经过多评分之间的任何显着的单变量关系。铁缺乏和乏力症状是HMB年轻女性的常见发现。与健康对照组相比，患有HMB的年轻女性乏力严重程度评分明显更高。

BACKGROUND & AIMS: :Colchicine is the treatment of choice in familial Mediterranean fever (FMF) for the prevention of both attacks and secondary amyloidosis. The overall nonresponder rate is about 5-10%. Anakinra is known to have good effectiveness in a severe autoinflammatory syndrome [chronic infantile neurological cutaneous and articular (CINCA) syndrome] and other recurrent hereditary periodic fevers. Pyrin--the protein involved in FMF--has a role in activating the proinflammatory cytokine interleukin (IL)-1beta. We report the effectiveness of the addition of an IL-1-receptor inhibitor (anakinra) to colchicine in controlling the febrile attacks and acute phase response in an adolescent with FMF resistant to colchicine.

背景与目标： : 秋水仙碱是家族性地中海发热 (FMF) 预防发作和继发性淀粉样变性的首选治疗方法。总体无应答率约为5-10%。众所周知，Anakinra在严重的自身炎症综合征 (慢性婴儿神经性皮肤和关节 (CINCA) 综合征) 和其他复发性遗传性周期性发烧中具有良好的疗效。Pyrin (参与FMF的蛋白质) 在激活促炎细胞因子白介素 (IL)-1β 中起作用。我们报告了在秋水仙碱中添加IL-1-receptor抑制剂 (anakinra) 在控制FMF对秋水仙碱耐药的青少年的发热发作和急性期反应中的有效性。

BACKGROUND & AIMS: :The aetiology of adolescent idiopathic scoliosis (AIS) is still unknown despite many years of research effort. Theories on AIS's aetiology have included mechanical, hormonal, metabolic, neuromuscular, growth, and genetic abnormalities. Amongst these, some factors may be epiphenomena rather than the cause itself. Other factors may even contribute to curve progression, rather than curve initiation. Current views maintain that AIS is a multifactorial disease with genetic predisposing factors [Lowe et al. in J Bone Joint Surg [Am] 82:1157-1168, 2000]. With improvements in diagnostic methods, imaging and genomics, there has been considerable recent work on aetiology. This review aims to bring readers up-to-date with the latest developments in scoliosis research.

背景与目标： : 尽管经过多年的研究，青少年特发性脊柱侧凸 (AIS) 的病因仍然未知。AIS病因学的理论包括机械，激素，代谢，神经肌肉，生长和遗传异常。其中，某些因素可能是现象，而不是原因本身。其他因素甚至可能导致曲线进展，而不是曲线启动。目前的观点认为，AIS是具有遗传易感因素的多因素疾病 [Lowe等人在J骨关节外科 [Am] 82:1157-1168，2000]。随着诊断方法，影像学和基因组学的改进，最近在病因学方面开展了大量工作。这篇综述旨在使读者了解脊柱侧弯研究的最新进展。

BACKGROUND & AIMS: This study examines the degree to which the existence of a pre-adolescent "chum" interacts with family and social environments to buffer mental distress in adolescents. 831 high school students participated in this study, (male476; mean age 16.7 +/- 1.0). Subjects were administered questionnaires assessing psychopathology and support systems. A pathway analyses model was used to investigate pathways and their interrelationships from chum to psychopathology and from social and family support to psychopathology. Only when adolescents experience weak parental bonding does chumship have a role in buffering distress.

背景与目标： 这项研究考察了青春期前 “chum” 的存在与家庭和社会环境相互作用以缓解青少年精神困扰的程度。831名高中生参加了这项研究 (male476; 平均年龄16.7 +/- 1.0)。对受试者进行了评估心理病理学和支持系统的问卷调查。使用途径分析模型来研究从chum到心理病理学以及从社会和家庭支持到心理病理学的途径及其相互关系。只有当青少年经历弱的父母关系时，才能在缓解痛苦中发挥作用。

BACKGROUND & AIMS: :Previous research indicates that tobacco craving predicts relapse to smoking among adult smokers attempting to quit. We hypothesized a similar relationship between craving and lapse (any smoking following a period of abstinence) among adolescent smokers during the treatment phase of a clinical trial. A visit was considered a lapse visit if the participant reported smoking or had a carbon monoxide level of 7 ppm or greater subsequent to an abstinent visit. A total of 34 participants (mean age = 14.9 years [SD = 1.3]; mean cigarettes/day = 18.0 [SD = 7.6]; mean Fagerström Test for Nicotine Dependence score = 6.8 [SD = 1.34]; 65% female), were included in the present analysis of 167 treatment visits. Logistic regression analyses showed a positive relationship between degree of craving, measured by the Questionnaire on Smoking Urges, and lapse during smoking cessation treatment (p = .013). Additionally, linear regression analyses demonstrated a strong positive association between cigarettes smoked per day and craving scores (p<.001). Taken together with other data, these findings suggest that degree of craving might influence tobacco abstinence for adolescent smokers. Thus monitoring and addressing craving appears useful to increase the success of adolescent smoking cessation.

背景与目标： : 先前的研究表明，对烟草的渴望预示着试图戒烟的成年吸烟者的吸烟复发。我们假设在临床试验的治疗阶段，青少年吸烟者的渴望和戒烟 (禁欲一段时间后吸烟) 之间存在相似的关系。如果参与者报告吸烟或在禁欲访视后一氧化碳水平达到7 ppm或更高，则该访视被认为是短暂访视。共有34名参与者 (平均年龄 = 14.9岁 [SD = 1.3]; 平均香烟/天 = 18.0 [SD = 7.6]; 平均fagerstr ö m测试的尼古丁依赖性评分 = 6.8 [SD = 1.34]; 65% 名女性) 被包括在167治疗访问的当前分析中。Logistic回归分析显示，通过吸烟冲动问卷测量的渴望程度与戒烟治疗期间的失误之间存在正相关关系 (p = .013)。此外，线性回归分析表明，每天吸烟与渴望得分之间存在很强的正相关 (p<.001)。结合其他数据，这些发现表明，渴望程度可能会影响青少年吸烟者的戒烟。因此，监测和解决渴望似乎有助于提高青少年戒烟的成功率。

BACKGROUND & AIMS: OBJECTIVE:Inadequate sunlight exposure and calcium intake during rapid growth at puberty lead to hypocalcemia, hypovitaminosis D and eventually to overt rickets. To determine serum biochemical findings of rickets in healthy 11-15 yr old girls, the effect of sunlight exposure and oral vitamin D supplementation on serum 25- hydroxy vitamin D and calcium administration in girls with abnormal findings during December 2002 through March 2003 in Tehran, Iran. METHODS:Healthy middle school girls were selected for estimation of vitamin D, calcium and phosphorus intake by a three-day food recall. And measurement of serum calcium, phosphorus, parathyroid hormone, alkaline-phosphatase and 25- hydroxyvitamin D concentration. The girls with abnormal findings divided in two groups. Hypovitaminosis D girls subdivided into two groups, supplementary sunlight exposure and vitamin- D administrated for them and calcium administration for the second group for 20 days. RESULTS:Of 414 girls, the mean daily vitamin D acquirement and calcium intake were 119 +/- 52 IU and 360 +/- 350 mg among all girls respectively. Mean serum 25-hydroxyvitamin D with two or more abnormal biochemical findings in 15 (3.6%) girls (group I) were 7.8 ng/ml and alkaline phosphatse with normal or low calcium in 29 (7%) girls (group II) was 1187 IU/L. Mean serum calcium was 8.2 mg % in 8 of 29 girls. Serum 25- hydroxyvitamin D before and after sunlight exposure was 7.1 +/- 1.9 ng/ml and 13.9 +/- 2.4 ng/ml and vitamin D administration was 7.4 +/- 1.8 ng/ml (group Ia) and 27.9 +/- 4.2 ng/ml (group Ib) respectively. Serum alkaline phosphatase before and after calcium administration were 1187 IU/L and 666 IU/L respectively. CONCLUSION:We conclude that low daily calcium intake and vitamin D acquirement are two important problems in Iranian girls during rapid growth at puberty; therefore, for prevention of overt rickets calcium and vitamin D Supplementation appear to be necessary.

背景与目标：

BACKGROUND & AIMS: :Use of electroconvulsive therapy (ECT) has been infrequently described in patients with systemic lupus erythematosus and is most commonly used in patients with catatonia. In this report, we describe the use of ECT in a young adolescent girl who had bipolar affective disorder associated with systemic lupus erythematosus and was treated with ECT for the depressive episode. The patient achieved remission with a course of 6 ECT treatments.

背景与目标： : 在系统性红斑狼疮患者中很少使用电惊厥疗法 (ECT)，最常用于卡托尼亚患者。在本报告中，我们描述了在患有与系统性红斑狼疮相关的双相情感障碍并接受ECT治疗的年轻少女中使用ECT的情况。患者通过6个疗程的ECT治疗获得缓解。

BACKGROUND & AIMS: :While adolescents have received increasing attention in the global HIV response and international strategies and commitments, adolescent mothers and their children remain largely overlooked in research, funding and, programming for health-related outcomes. We conducted an extensive scoping review of current evidence on the experiences of adolescent mothers affected by HIV and their children in this region. We included published literature and conference abstracts, complemented by consultations with key stakeholders, and a review of documents through grey literature searching. First, we summarise the experiences of adolescent mothers and their children related to HIV and key health and development indicators. The syndemic of early motherhood and HIV in sub-Saharan Africa increases the vulnerability of adolescent mothers and their children. We then highlight lessons from a series of promising programmes focused on supporting adolescent mothers through novel approaches. In sub-Saharan Africa, supporting adolescent mothers living in high HIV-risk communities is critical not only to eliminate HIV/AIDS, but also to attain the Sustainable Development Goals. While research on and programming for adolescent mothers and their children is growing, the complex needs for this vulnerable group remain unmet. We conclude with evidence gaps and programming priorities for adolescent mothers affected by HIV and their children.

背景与目标： : 尽管青少年在全球艾滋病毒应对措施以及国际战略和承诺中受到越来越多的关注，但青少年母亲及其子女在与健康有关的成果的研究，资金和方案编制方面仍然被忽视。我们对该地区受艾滋病毒影响的青春期母亲及其子女的经历的当前证据进行了广泛的范围界定审查。我们包括了已发表的文献和会议摘要，并与主要利益相关者进行了磋商，并通过灰色文献搜索对文件进行了审查。首先，我们总结了青春期母亲及其子女与艾滋病毒有关的经验以及关键的健康与发展指标。撒哈拉以南非洲地区早期孕产和艾滋病毒的共同感染增加了青春期母亲及其子女的脆弱性。然后，我们重点介绍了一系列有前途的计划的教训，这些计划侧重于通过新颖的方法支持青春期母亲。在撒哈拉以南非洲，支持生活在艾滋病毒高风险社区的青春期母亲不仅对消除艾滋病毒/艾滋病至关重要，而且对实现可持续发展目标也至关重要。尽管对青少年母亲及其子女的研究和规划正在增长，但对这一弱势群体的复杂需求仍未得到满足。最后，我们为受艾滋病毒影响的青春期母亲及其子女提供了证据空白和计划优先事项。

BACKGROUND & AIMS: :This case series from a hospital-based academic in vitro fertilization clinic outlines the feasibility of oocyte cryopreservation for transgender male adolescents after varying degrees of exposure to pubertal blockers and/or testosterone. A description of each patient's oocyte cryopreservation cycle is reviewed, including prior exposure to pubertal blockers and/or testosterone, anti-Mullerian hormone level, stimulation medications, trigger injections, number of oocytes retrieved and cryopreserved, and complications. All patients tolerated stimulation and retrieval well and had mature oocytes cryopreserved in each cycle. There were no complications. Adolescent transgender males who choose to undergo oocyte cryopreservation tolerate the process well, reinforcing the importance of fertility preservation in providing comprehensive care for transgender patients.

背景与目标： : 该病例系列来自一家医院的学术体外受精诊所，概述了变性男性青少年在不同程度暴露于青春期阻滞剂和/或睾丸激素后进行卵母细胞冷冻保存的可行性。回顾了每个患者的卵母细胞冷冻保存周期的描述，包括先前暴露于青春期阻滞剂和/或睾丸激素，抗苗勒氏激素水平，刺激药物，触发注射，回收和冷冻保存的卵母细胞数量以及并发症。所有患者对刺激和恢复的耐受性良好，并且在每个周期中都冷冻保存了成熟的卵母细胞。没有并发症。选择进行卵母细胞冷冻保存的青春期跨性别男性可以很好地耐受该过程，从而增强了保留生育能力在为跨性别患者提供全面护理中的重要性。

BACKGROUND & AIMS: :We examined the influence of two measures of maternal nutritional status: prepregnant body mass (kilograms/meter2 ) and Weight gain during pregnancy (adjusted for duration of gestation) on spontaneous preterm delivery (<37 completed Weeks' gestation) and duration of gestation, as well as on low birthweight (<2,500 grams) and small-for-gestational-age (SGA) in pregnant adolescents. Inadequate Weight gain for gestation increased the risk of spontaneous preterm delivery when prematurity was reckoned by the obstetric estimate (Adjusted Odds Ratio, AOR = 1.75 95% CI 1.22-2.50) or from the mother's LMP (AOR = 1.49 95% CI 1.10-2.02). In linear models, gestation duration was significantly reduced, by more than half a week, when reckoned from eiter estimate of gestation. However, the association between preterm birth or gestation duration and prepregnancy body mass was not consistent and depended on the method of estimating gestation. Low birthweight and SGA were each significantly associated with inadequate weight gain during pregnancy as well as with prepregnant body mass. These results suggest that current maternal nutritional status, as measured by weight gain during pregnancy, may influence preterm delivery and gestation duration. The inconsistent results obtained with prepregnancy body mass may reflect a size bias inherent in the obstetric estimate of gestation, rather than effects of prepregnant maternal nutritional status on gestation.

背景与目标： : 我们研究了两种母亲营养状况指标的影响: 怀孕前体重 (千克/米2) 和怀孕期间体重增加 (根据妊娠持续时间进行调整) 对自发早产 (<37个完整妊娠周) 和妊娠持续时间的影响，以及怀孕青少年的低出生体重 (<2,500克) 和小于胎龄儿 (SGA)。当产科估计值 (调整后的比值比，AOR = 1.75 95% CI 1.22-2.50) 或母亲的LMP (AOR = 1.49 95% CI 1.10-2.02) 估计早产时，妊娠体重增加不足会增加自发早产的风险。在线性模型中，根据eiter对妊娠的估计，妊娠持续时间显着减少了半周以上。然而，早产或妊娠持续时间与孕前体重之间的关联并不一致，并且取决于估计妊娠的方法。低出生体重和SGA均与怀孕期间体重增加不足以及怀孕前的体重显着相关。这些结果表明，以怀孕期间体重增加衡量的当前孕产妇营养状况可能会影响早产和妊娠持续时间。与孕前体重获得的不一致结果可能反映了产科妊娠估计中固有的大小偏差，而不是孕前孕妇营养状况对妊娠的影响。

BACKGROUND & AIMS: PURPOSE:Pregnancy rates among adolescents have declined in the U.S. and Britain but remain high compared with other high-income countries. This comparison describes trends in pregnancy rates, recent sexual activity, and contraceptive use among women aged 16-19 years in the U.S. and Britain to consider the contribution of these two behavioral factors to the decline in pregnancy rates in the two countries and the differences between them. METHODS:We use data from two rounds of the U.S. National Survey of Family Growth, conducted 2002-2003 and 2011-2015, and the British National Survey of Sexual Attitudes and Lifestyles, conducted 2000-2001 and 2010-2012, to describe population-level differences between countries and over time in sexual activity and contraceptive use. We calculate pregnancy rates using national births and abortions data. RESULTS:Pregnancy rates declined in both countries; this began earlier in the U.S. and was steeper. There was no change in sexual activity in Britain, but in the U.S., the proportion reporting recent sex declined. In both countries, there was a shift toward more effective contraception. A higher proportion in Britain than the U.S. reported ever having had sex (65% vs. 49%) and sex in the last year (64% vs. 45%), 6 months (59% vs. 39%), and 4 weeks (48% vs. 29%). A higher proportion in Britain reported using more effective contraception (68% vs. 52%). CONCLUSIONS:In both countries, improvements in contraceptive use have contributed substantially to declines in pregnancy rates; however, the steeper decline in the U.S. likely also reflects declines in recent sex occurring only in that country.

背景与目标：