Does Gardasil cause birth defects?

This study will describe and evaluate any congenital malformations in children born by women who received the HPV vaccine Gardasil during or shortly before pregnancy, and whether the malformation may be related to vaccination.

Published: 12.04.2016, last updated: 20.10.2020

Different causes of congenital malformations

It is assumed that one in every 30 children born to a greater or lesser extent has a congenital malformation or developmental defect.

The causes of congenital malformations are many and partly unknown. Broadly speaking, the known causes can be divided into environmental influences the mother is exposed to during pregnancy (such as drugs, X-rays or infections) and hereditary conditions.

In an estimated 50 % of cases, however, the cause of the malformation is not known, but it is thought that hereditary predisposition may play a role in more cases than we know of today.

The Medical Birth Registry of Norway compiles statistics on all births in Norway, as well as matters concerning pregnancy and birth that are of importance to the mother and the child's health. In Norway, therefore, we have a good overview of children born with malformations.

No reported increase in risk of congenital malformations

In Norway, the HPV vaccine Gardasil has been approved for women between 9 and 26 years of age. These are women of or close to childbearing age. Pregnant women are not recommended to take the vaccine. Cases where the vaccine was nevertheless given during or shortly before pregnancy are included in this study.

During the trial of the vaccine, 20,551 women participated worldwide. Of these, 3 620 became pregnant during the period in question. Based on research studies in which these are included, we have no evidence that the vaccine has an undesirable effect on the fetus.

Since then, the vaccine has been given to millions of women worldwide. There have been no reports that the HPV vaccine increases the risk of having children with congenital malformations.

The purpose of this study is to capture any adverse events and detect any rare side effects should they nevertheless occur when the vaccine is now available on the market.

Nordic cooperation

The study combines information from the Norwegian Immunisation Registry (SYSVAK), the Norwegian Patient Registry and the Medical Birth Registry.

If a child with congenital malformation(s) is identified, an expert panel consisting of four Nordic specialists will assess whether there is a link between the vaccine and the malformations. The study is being conducted in parallel in Norway, Sweden, Denmark and Iceland.

Initially, the study will determine whether there is an increased risk of malformations in children exposed to Gardasil in the womb. If the survey indicates this, further studies are initiated.


Project participants

Cancer Registry of Norway

Mari Nygård, Giske Ursin, Bo T. Hansen and Ragnhild Flingtorp.



Oslo University Hospital, Rikshospitalet: Arvid Heiberg

The Danish Cancer Society: Kristen Egebjerg Jensen and Susanne Krüger Kjær

Karolinska Institutet: Maria Hortlund

The Icelandic Cancer Society: Laufey Traggvadottir


The drugmaker Merck Inc. is required to conduct the study by the Food and Drug Administration (FDA). The MSD Norway is funding the study.