Iles-Caven Yasmin, Northstone Kate, Golding Jean
Population Health Sciences, Bristol Medical School, University of Bristol, Oakfield House, Oakfield Grove, Bristol, BS8 2BN, UK.
Wellcome Open Res. 2020 May 22;5:100. doi: 10.12688/wellcomeopenres.15976.1. eCollection 2020.
Enrolling a cohort in pregnancy can be methodologically difficult in terms of structuring data collection. For example, some exposures of interest may be time-critical while other (often retrospective) data can be collected at any point during pregnancy. The Avon Longitudinal Study of Parents and Children (ALSPAC) is a prime example of such a cohort. ALSPAC aimed to enrol as many pregnant women as possible in a geographically defined area with an expected date of delivery between April 1991 and December 1992. The ideal was to enrol women as early in pregnancy as possible, and to collect information, when possible, at two fixed gestational periods (18 and 32 weeks). A variety of methods were used to enrol participants. Approximately 80% of eligible women resident in the study area were enrolled. Gestation at enrolment ranged from 4-41 (median = 14) weeks of pregnancy. Given this variation in gestation, we describe the various decisions that were made in regard to the timing of questionnaires to ensure that appropriate data were obtained from the pregnant women. 45% of women provided data during the first trimester; this is less than ideal but reflects the fact that many women do not acknowledge their pregnancy until the first trimester is safely completed. Data collection from women at specific gestations (18 and 32 weeks) was much more successful (80-85%). Unfortunately, it was difficult to obtain environmental data during the first trimester. Given the time critical nature of exposures during this trimester, researchers must take the gestational age at which environmental data was collected into account. This is particularly important for data collected using the questionnaire named 'Your Environment' (using data known as the A files).
就数据收集的组织安排而言，招募孕期队列在方法学上可能具有挑战性。例如，一些感兴趣的暴露因素可能对时间要求严格，而其他（通常是回顾性的）数据可以在孕期的任何时间点收集。雅芳亲子纵向研究（ALSPAC）就是这样一个队列的典型例子。ALSPAC旨在在一个地理区域内尽可能多地招募孕妇，预期分娩日期在1991年4月至1992年12月之间。理想情况是尽可能在孕早期招募女性，并尽可能在两个固定的孕周（18周和32周）收集信息。采用了多种方法来招募参与者。居住在研究区域内约80%符合条件的女性被招募。入组时的孕周范围为妊娠4 - 41周（中位数 = 14周）。鉴于孕周存在这种差异，我们描述了在问卷发放时间方面做出的各种决策，以确保从孕妇那里获得适当的数据。45%的女性在孕早期提供了数据；这并不理想，但反映了许多女性直到孕早期安全结束才承认自己怀孕这一事实。在特定孕周（18周和32周）从女性那里收集数据要成功得多（80 - 85%）。不幸的是，在孕早期很难获得环境数据。鉴于孕早期暴露因素对时间的严格要求，研究人员必须考虑收集环境数据时的孕周。这对于使用名为“你的环境”的问卷（使用称为A文件的数据）收集的数据尤为重要。
