CC-BY-NC-ND 4.0 · AJP Rep 2017; 07(04): e205-e210
DOI: 10.1055/s-0037-1607028
Case Report
Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Anti-M Alloimmunization: Management and Outcome at a Single Institution

Bethany Stetson1, Scott Scrape2, Kara Beth Markham1
  • 1Division of Maternal Fetal Medicine, Department of Obstetrics and Gynecology, The Ohio State University Wexner Medical Center, Columbus, Ohio
  • 2Department of Pathology, The Ohio State University Wexner Medical Center, Columbus, Ohio
Further Information

Publication History

02 May 2017

15 August 2017

Publication Date:
22 November 2017 (online)


Objective The objective of this study was to review the management strategies and outcomes in gravidas with anti-M alloimmunization over 15 years.

Study Design Data collected from 195 pregnant patients with anti-M antibodies from July 2000 through June 2016 were reviewed retrospectively. We analyzed indirect antiglobulin test titer results, paternal or fetal/neonatal M antigen status, antepartum course, and perinatal outcomes.

Results Anti-M antibodies were found in 146 women and 195pregnancies. Among those with positive indirect antiglobulin tests, 193 pregnancies had titers at or below 1:4. Only one patient with an initial low titer experienced a more than twofold increase to a titer 1:64. Two women underwent an amniocentesis and cordocentesis. Ninety-five (73.6%) of the 129 infants tested were positive for the M antigen. Nine infants required phototherapy. There were no cases of hemolytic disease of the fetus or newborn, mild or severe.

Conclusion The incidence of severe hemolytic disease of the newborn due to anti-M is extremely low. We found no cases in our review of 195 pregnancies, despite several cases of severe hemolytic disease of the newborn reported in the literature. We have created an algorithm for the management of anti-M antibodies in pregnancy based on our data and extensive literature review.


This study was approved by IRB 2015H0436 and was presented as poster presentation #192 at the 37th Annual Society for Maternal Fetal Medicine Meeting on January 26, 2017, in Las Vegas, NV.