# Pregnancy algorithm

The VigiBase pregnancy algorithm is a rule-based method developed to identify pregnancy-related reports. More specifically, it uses structured data elements to identify reports of maternal exposure to a medicinal product before or during pregnancy, with or without adverse events in the pregnant person or the prenatally exposed. It does not flag patients over 50 years, paternal exposures, or lactation reports.

The algorithm consists of two main steps, as showed in Figure 1 below. Firstly, reports that are considered unlikely to be pregnancy-related are ruled out. Secondly, if no rule-out step is met, reports are flagged if they meet any of the rule-in conditions.

<figure><img src="https://844234868-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FD7MbxF2Gm1Bf1uqE3mOA%2Fuploads%2Fd1KEksgjc7rFS3Schcmd%2FPregancy_1.png?alt=media&#x26;token=15edfbd8-a99f-4cb1-a155-61efe7a81d38" alt=""><figcaption></figcaption></figure>

Figure 1. The VigiBase pregnancy algorithm

According to UMC’s evaluation of the algorithm based on around 8000 manually annotated reports, the algorithm is expected to identify 75% of all pregnancy cases in VigiBase (i.e. recall/sensitivity). When focusing on reports transmitted in the E2B format, this proportion increases to 91%. Additionally, 92% of the reports identified by the algorithm as pregnancy cases are correctly classified (i.e. precision/positive predictive value), regardless of restricting to the E2B format.

#### Get to know more

* [Comprehensive evaluation of algorithm - Research poster](https://who-umc.org/media/j2cpykuc/pregnancy_poster_digital.pdf)
* [Uncovering pregnancy cases in VigiBase - Uppsala Reports](https://uppsalareports.org/articles/uncovering-pregnancy-cases-in-vigibase/)
* Sandberg, L., Vidlin, S.H., K-Pápai, L. *et al.* Uncovering Pregnancy Exposures in Pharmacovigilance Case Report Databases: A Comprehensive Evaluation of the VigiBase Pregnancy Algorithm. *Drug Saf* (2025). <https://doi.org/10.1007/s40264-025-01559-0>


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