Department of Obstetrics and Gynecology, University of Washington School of Medicine, Seattle, WA, USA.
BMC Pregnancy Childbirth. 2010 Feb 23;10 Suppl 1(Suppl 1):S2. doi: 10.1186/1471-2393-10-S1-S2.
Normal and abnormal processes of pregnancy and childbirth are poorly understood. This second article in a global report explains what is known about the etiologies of preterm births and stillbirths and identifies critical gaps in knowledge. Two important concepts emerge: the continuum of pregnancy, beginning at implantation and ending with uterine involution following birth; and the multifactorial etiologies of preterm birth and stillbirth. Improved tools and data will enable discovery scientists to identify causal pathways and cost-effective interventions. PREGNANCY AND PARTURITION CONTINUUM: The biological process of pregnancy and childbirth begins with implantation and, after birth, ends with the return of the uterus to its previous state. The majority of pregnancy is characterized by rapid uterine and fetal growth without contractions. Yet most research has addressed only uterine stimulation (labor) that accounts for <0.5% of pregnancy. ETIOLOGIES: The etiologies of preterm birth and stillbirth differ by gestational age, genetics, and environmental factors. Approximately 30% of all preterm births are indicated for either maternal or fetal complications, such as maternal illness or fetal growth restriction. Commonly recognized pathways leading to preterm birth occur most often during the gestational ages indicated: (1) inflammation caused by infection (22-32 weeks); (2) decidual hemorrhage caused by uteroplacental thrombosis (early or late preterm birth); (3) stress (32-36 weeks); and (4) uterine overdistention, often caused by multiple fetuses (32-36 weeks). Other contributors include cervical insufficiency, smoking, and systemic infections. Many stillbirths have similar causes and mechanisms. About two-thirds of late fetal deaths occur during the antepartum period; the other third occur during childbirth. Intrapartum asphyxia is a leading cause of stillbirths in low- and middle-income countries.
Utilizing new systems biology tools, opportunities now exist for researchers to investigate various pathways important to normal and abnormal pregnancies. Improved access to quality data and biological specimens are critical to advancing discovery science. Phenotypes, standardized definitions, and uniform criteria for assessing preterm birth and stillbirth outcomes are other immediate research needs.
Preterm birth and stillbirth have multifactorial etiologies. More resources must be directed toward accelerating our understanding of these complex processes, and identifying upstream and cost-effective solutions that will improve these pregnancy outcomes.
妊娠和分娩的正常和异常过程还不甚了解。这篇全球报告的第二篇文章解释了导致早产和死产的病因，并确定了知识上的关键空白。两个重要概念出现了：妊娠的连续体，始于着床，止于产后子宫的复旧；以及早产和死产的多因素病因。改进的工具和数据将使发现科学家能够确定因果途径和具有成本效益的干预措施。妊娠和分娩连续体：妊娠和分娩的生物学过程始于着床，产后则以子宫回到孕前状态而结束。大多数妊娠的特点是子宫和胎儿快速生长，没有宫缩。然而，大多数研究只关注占妊娠不到 0.5%的子宫刺激（分娩）。病因：早产和死产的病因因孕龄、遗传和环境因素而异。所有早产的大约 30%是由于母亲或胎儿的并发症，如母亲疾病或胎儿生长受限。通常，导致早产的常见途径发生在以下孕龄：（1）感染引起的炎症（22-32 周）；（2）胎盘血栓引起的蜕膜出血（早产）；（3）应激（32-36 周）；（4）子宫过度扩张，常由多胎引起（32-36 周）。其他因素包括宫颈机能不全、吸烟和全身感染。许多死产有类似的病因和机制。大约三分之二的晚期胎儿死亡发生在产前；三分之一发生在分娩过程中。产时窒息是中低收入国家死产的主要原因。建议：利用新的系统生物学工具，现在为研究人员提供了机会，研究对正常和异常妊娠很重要的各种途径。更好地获取高质量的数据和生物标本对于推进发现科学至关重要。表型、标准化定义和评估早产和死产结局的统一标准是其他当前的研究需求。结论：早产和死产有多种病因。必须投入更多资源来加速我们对这些复杂过程的理解，并确定上游的、具有成本效益的解决方案，以改善这些妊娠结局。
