Comprehensive data
Denmark’s health care system has two key features that make it an attractive setting in which to conduct such a study – the first being its universal health care. The second advantage is that the country enacted several health registries in the 1970s and 1980s that enable the collection of more comprehensive data. For example, the Danish National Patient Register is a population-based registry that spans the entire nation, facilitating epidemiological research with what the study’s authors describe as “high generalizability.” Providing additional insights regarding the patient story helps add context to pregnancy and outcomes. Among the data collected on the women studied were demographics, contact information, and abortions, both spontaneous and medically induced. The country uses other databases and registries to capture additional data. For example, the Register of Legally Induced Abortions provides data regarding the context of medically induced abortions. In contrast, the Danish Medical Birth Registry provides context regarding specified variables regarding women’s pregnancies, delivery, and perinatal outcomes. Finally, the population’s education register offers information regarding patients’ educational history.
A key strength of this study is that the long duration of follow-up data from the Danish Medical Birth Registry, along with its comprehensive data collection, eliminates recall bias. Universal access to health care also improves the generalizability of data. A limitation of the study is its lack of data on maternal smoking and its effects on low gestational weights. The study also has some data gaps, including body mass index information missing from a large portion of the cohort. Finally, the sample size of newborns born to mothers who had received DMT therapy within the last 6 months of gestation was too underpowered to stratify based on first on first-line or second-line treatment.
Dr. Magyari served on scientific advisory boards for Biogen, Sanofi, Teva, Roche, Novartis, and Merck. She has also received honoraria for lecturing from Biogen, Merck, Novartis, Sanofi, Genzyme, and has received research support and support for congress participation from Biogen, Genzyme, Teva, Roche, Merck, and Novartis. Coauthors disclosed various fees received from Merck, Novartis, Biogen, Roche, Sanofi Genzyme, and Teva.