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Original research
Pregnancy outcomes in women with neurofibromatosis 1: a Danish population-based cohort study
  1. Line Kenborg1,
  2. Cristina Boschini2,
  3. Pernille E Bidstrup3,
  4. Susanne O Dalton4,
  5. Karoline Doser1,
  6. Thomas T Nielsen1,
  7. Anja Krøyer1,
  8. Christoffer Johansen3,5,
  9. Kirsten Frederiksen2,
  10. Sven Asger Sørensen6,
  11. Hanne Hove7,
  12. John R Østergaard8,
  13. John J Mulvihill9,
  14. Jeanette F Winther1,10
  1. 1Childhood Cancer Research Group, Danish Cancer Society Research Center, Copenhagen, Denmark
  2. 2Statistics and Data Analysis, Danish Cancer Society Research Center, Copenhagen, Denmark
  3. 3Psychological Aspects of Cancer, Danish Cancer Society Research Center, Copenhagen, Denmark
  4. 4Survivorship and Inequality in Cancer, Danish Cancer Society Research Center, Copenhagen, Denmark
  5. 5Department of Oncology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
  6. 6Department of Neurogenetics, Institute of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
  7. 7Department of Clinical Genetics, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
  8. 8Center for Rare Diseases, Department of Pediatrics and Adolescent Medicine, Aarhus University Hospital, Aarhus, Denmark
  9. 9Department of Pediatrics, University of Oklahoma, Oklahoma City, OK, USA
  10. 10Department of Clinical Medicine, Faculty of Health, Aarhus University, Aarhus, Denmark
  1. Correspondence to Dr Line Kenborg, Childhood Cancer Research Group, Danish Cancer Society Research Center, 2100 København, Denmark; kenborg{at}


Background The probability of a pregnancy, live birth, stillbirth and abortion has never been assessed in women with neurofibromatosis 1 (NF1) in a large population-based study.

Methods We included 1006 women (15–49 years) registered with NF1 in the Danish National Patient Registry or followed in two national Centers for Rare Diseases and 10 020 women from the Danish population. Information on pregnancy outcomes was ascertained from health registries. Cumulative incidence, mean cumulative count, hazard ratios (HRs) and proportion ratios (PRs) with 95% CIs were calculated.

Results The cumulative incidence of a first pregnancy at age 50 years was slightly lower in women with NF1 (74%; 95% CI 70 to 77) than in population comparisons (78%; 95% CI 77 to 79). When all pregnancies were included, two pregnancies were expected per woman at age of 50 years, irrespective of a NF1 diagnosis. The hazard of a pregnancy did not differ between women with NF1 (HR 1.03; 95% CI 0.95 to 1.11) and the comparisons after adjustment for somatic and psychiatric disease. The proportion of pregnancies that resulted in a live birth was 63% (783/1252) among women NF1 and 68% (8432/12 465) among the comparisons, yielding a PR of 0.95 (95% CI 0.90 to 1.00). The proportions of stillbirths (PR 2.83; 95% CI 1.63 to 4.93) and spontaneous abortions (PR 1.40; 95% CI 1.09 to 1.79) were increased in women with NF1.

Conclusions A similar hazard for pregnancy was observed for women with NF1 and population comparisons after adjustment for potential medical consequences of NF1. However, women with NF1 experienced more spontaneous abortions and stillbirths.

  • obstetrics
  • genetic fitness
  • genetics
  • population

Statistics from


  • Contributors LK, PEB, SOD, CJ, SAS, HH, JRØ and JFW contributed to the conception of the study. LK, KF and JW designed the study. LK, AK, TTN, HH, JRØ and JFW contributed to acquisition of data. AK and TTN prepared all data. CB and KF analysed data. LK, CB, KF, KD, JJM and JFW interpreted the results. LK drafted the manuscript and revised the manuscript. CB, PEB, SOD, KD, TTN, AK, CJ, KF, SAS, HH, JRØ, JJM and JFW reviewed and revised the manuscript critically for important intellectual content and approved the final manuscript for submission. All coauthors agree to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

  • Funding The study was supported by a grant from the US Army Medical Research and Materiel Command (award number W81XWH-14-1-0054). LK, CB, KD, TTN and AK are all supported by the grant from the US Army Medical Research and Materiel Command.

  • Disclaimer The funders of the study had no role in the study design; data collection, analysis, or interpretation; or in the writing of the report; and in the decision to submit the article for publication.

  • Competing interests None declared.

  • Patient consent for publication Not required.

  • Ethics approval The study was approved by the Danish Protection Agency (Record 2014–41–2935) and the Human Research Protection Office (HRPO) (A:18 370.i).

  • Data availability statement No data are available. Data are not available due to Danish legislation. However, the study group welcomes collaboration with other researchers using our registry data. Study protocols can be planned in collaboration with us, and the study material can be analysed accordingly at the server of Statistics Denmark, where all data are stored.

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