Time to conceive


Some women with MS are concerned that coming off their MS therapy to get pregnant will worsen their condition [1]. Estimates from the general population in Germany suggest that most couples will not conceive during their first cycle, around half will not conceive by their third, and 10-20% of couples will not conceive after one year [2].

An important modifier of the time to conception is age [3]. Delaying pregnancy to later in life is becoming increasingly common around the world. In most OECD countries, the average age at which women give birth now stands at 30 years or above (see figure 1 for an example of fertility rates in Italy) [4].


Women with MS may delay childbearing even further [5]. The mean age of pregnant women with MS was 32.5 years compared to 29.3 years for those without MS according to US administrative claims data for 2014 [5]. Women over 30 years of age may require more time to conceive and carry a higher risk of miscarriage (see figure 2) [5,6].



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Figure 1: Fertility rates (births per 1000 women) in Italy by five-year age group [4]

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Figure 2: Cumulative probability of conception by age categories [6]


Little is known about time to pregnancy in women with MS. In general, MS does not seem to have a significant impact on the ability to conceive [7]. However, 40-80% of women with MS report diminished sexual activity [8,9]. A survey of women with MS in Switzerland reported that a time lapse of more than 6 months between stopping MS therapy and conception is common [10].


While deferring MS treatment to start a family was once common practice, today this is no longer advised.


Delaying treatment until after patients have completed their families may lead to the development of irreversible disability in at least some cases [11]. Treating MS early in the course of the disease may help prevent long-term disability. However, any patient of childbearing age or who wishes to start a family should carefully consider their choice of treatment [11].


The pregnancy section of the European Summary of Product Characteristics for interferon beta including BETAFERON refers to a large amount of data (more than 1000 pregnancy outcomes) from interferon beta registries, national registries and post-marketing experience [12]. These data indicate no increased risk of major congenital anomalies after pre-conception exposure or exposure during the first trimester of pregnancy. Experience with exposure during the second and third trimester remains limited, as treatment is commonly discontinued after pregnancy is confirmed. If clinically needed, interferon beta therapy like BETAFERON may be considered during pregnancy [12]. This approach is generally reflected in clinical practice guidelines and expert opinion statements advising that interferon beta therapy like BETAFERON may be continued until pregnancy is confirmed [13-20].


Assisted reproductive treatment (ART)

Return to 'Pregnancy'





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OECD: Organisation for Economic Co-operation and Development


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  • Johnson JA et al. J Obstet Gynaecol Can 2012; 34(1): 80-93. Return to content
  • OECD Family Database. Available at: http://www.oecd.org/els/family/database.htm, update 29.5.2019. Accessed April 15 2020. Re-access of database on August 23, 2022: A new report has become available in June 2022 including 2020 data. As differences between 2017 and 2020 are marginally, we continue to show the data as per the previous report. Return to content
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  • BETAFERON European Summary of Product Characteristics, October 2020. Available at: https://www.ema.europa.eu/en/documents/product-information/betaferon-epar-product-information_en.pdf Return to content
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