Natalizumab use during the third trimester of pregnancy

In these case series, 12 women with 13 pregnancies and highly active multiple sclerosis treated with natalizumab during their third trimester of pregnancy were observed to assess the clinical and laboratory effects of natalizumab on the newborns. Serum natalizumab concentrations were determined using a validated sandwich enzyme-linked immunosorbent assay method.

Of the 12 women treated with natalizumab during the last trimester of pregnancy, 10 became pregnant while taking natalizumab. Five of these women stopped natalizumab treatment in the first trimester but required retreatment for severe relapses during pregnancy. The other five continued natalizumab treatment through the whole pregnancy owing to natalizumab-withdrawal relapses prior to pregnancy. Three additional women requiring third trimester treatment had stopped natalizumab therapy before pregnancy and relapsed during the first trimester. All women with relapses during pregnancy were refractory to treatment with high-dose intravenous steroids. The natalizumab withdrawal pregnancy relapses were severe and, after natalizumab treatment was started, disease activity stabilized in all women.

Laboratory abnormalities and/or medical conditions were observed in 11 of the 13 newborns. Hematological abnormalities were found in 10 newborns including anemia (n = 8) and thrombocytopenia (n = 6). One mother experienced a catastrophic relapse requiring intense treatment and her child was born small for gestational age. Another child had a cystic formation in the caudo-thalamic region (potentially compatible with an intracranial hemorrhage) detected by screening ultrasonography after delivery that was no longer detectable by 12 weeks of age. One malformation — an atrioventricular septal defect (atrial septal defect I and II) that needed surgical intervention—was reported (this infant was also exposed to valproate in addition to natalizumab throughout pregnancy). One mother contributed two pregnancies. Her first child showed a moderate anemia.

Authors: Haghikia A, Langer-Gould A.
Source: JAMA Neurol. 2014 May 12. doi: 10.1001/jamaneurol.2014.209. [Epub ahead of print]
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