Gestation at completion of prenatal questionnaires in ALSPAC

Yasmin L Iles-Caven*, Kate Northstone, Jean Golding

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

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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).
Original languageEnglish
Article number100
Number of pages9
JournalWellcome Open Research
Issue number5
Publication statusPublished - 22 May 2020

Structured keywords

  • Bristol Population Health Science Institute


  • pregnancy
  • questionnaire administration
  • mothers
  • fathers
  • birth cohort study


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