Using Interferon-beta While Pregnant Does Not Influence Child Size at Birth, MS Study Finds

Treatment with interferon-beta therapy during pregnancy in women with multiple sclerosis (MS) does not influence children’s gestational age, birth weight, length, or head size, researchers report.

The study with those findings, “The association between exposure to interferon-beta during pregnancy and birth measurements in offspring of women with multiple sclerosis,” was published recently in the journal PLoS ONE.

Interferon-beta (IFN-beta) treatments are a mainstay of approved MS therapies. Although current guidelines recommend cessation during pregnancy, small-scale studies show conflicting evidence about the safety of prenatal exposure to IFN-beta.

Now, a team led by researchers at the Karolinska Institutet in Sweden, investigated whether, among those born to women with MS, babies prenatally exposed to IFN-beta were born smaller than those who were not prenatally exposed to any MS disease-modifying therapies.

For this purpose, investigators used datasets from Sweden and Finland. A total of 411 pregnancies exposed to interferon-beta were identified in Sweden between 2005 and 2014, while Finnish records revealed 232 pregnancies meeting that criteria.

Data was compared to pregnancies not exposed to any disease-modifying therapies, which included 835 gestations in Sweden and 331 in Finland. The IFN-beta exposure window was considered from six months prior to the  patient’s last menstrual period to the end of the pregnancy.

Results showed that Swedish infants exposed to IFN-beta were on average 28 grams heavier, 0.01 cm longer, and had a 0.14 cm larger head circumference. Finnish babies were 50 grams lighter, 0.02 cm shorter, and had a 0.22 cm smaller head circumference, compared to unexposed infants. However, these differences were not statistically significant overall.

According to the team, such differences in baby weight, length, or head size  probably are due to other factors and not related to exposure to IFN-beta.

Researchers also noted there were no differences in gestational ages between exposed and unexposed groups, and between siblings exposed and siblings unexposed to IFN-beta.

“In summary, the evidence from this large population-based study indicate no association between IFN-beta exposure and fetal growth or gestational age among infants of women with MS,” the researchers wrote. “Exposure to IFN-beta during pregnancy does not influence birth weight, length, or head circumference.”

Of note, in September the European Medicines Agency (EMA) announced that women with relapsing MS can be treated with IFN-beta while pregnant and breastfeeding — namely with Biogen’s Plegridy (peginterferon beta-1a) and Avonex (interferon beta-1a), and Rebif (interferon beta-1a) by Merck KGaA (known as EMD Serono in North America).

The recommendation by EMA’s Committee for Medicinal Products for Human Use (CHMP) was based on data from the European Interferon Beta Pregnancy Registry, and from the national health registers of Finland and Sweden that were used for this study.