Gestational Age and Loss of Maternal Measles Antibodies in Infants : A Call for Measles Immunization Review

Maternal measles antibodies (MMA) are actively transferred in mother-infant pairs during third trimester of pregnancy. Gestational age (GA) affects the levels of MMA such that longer GA may result in infants starting out with high levels of MMA. To determine the influence of GA on the loss of MMA of newborn infants in North-Eastern, Nigeria, a prospective study was conducted on newborn infants at Maiduguri. Sera were collected at birth and at six months of age. Enzyme linked immunosorbent assay (ELISA) was used to measure MMA while GA was determined using the last menstrual period, ultrasound scan reports and the Dubowitz criteria. Seventeen (89.5 %) preterm, 43 (95.6 %) term and 14 (100 %) postterm had protective levels of MMA at birth. Two (10.5 %) preterm, nine (20.0%) term and two (14.3 %) postterm had protective MMA at six months of age. Significant decline of mean MMA levels was seen in these infants at six months of age (p = 0.005), which was independent of their GA. These infants may be prone to measles at an earlier age (less than six months). Therefore, the current recommendation of measles immunization to infants at nine months of age may require reconsideration.