Kagan KO, Enders M, Hoopmann M, et al. - The efficacy of the hyperimmunoglobulin (HIG) treatment was investigated in women with a recent primary CMV infection up to 14 weeks’ gestation. In this ongoing observational study, enrollment criteria included the presence of confirmed, very recent primary CMV infection in the first trimester and a gestational age at first HIG administration of ≤ 14 weeks. Treatment was provided to 149 pregnant women and 153 fetuses. Outcomes support HIG as preventive against maternal‐fetal transmission in a case of a primary CMV infection, however, its benefits are achieved only in women with a very recent primary infection in the first trimester or during the periconceptional period, a timely start and a suitable treatment interval.