Ability of History Taking Alone to Identify Early Pregnancies Among Potential Measles Vaccinees

OBJECTIVE This study was undertaken to determine the ability of history taking alone, compared with pregnancy testing, to identify early pregnancies among potential female measles vaccinees. METHODS As part of an institution-wide measles immunization program, 326 female health care workers (HCWs) who denied being pregnant underwent a urine pregnancy test prior to vaccination. RESULTS Of the 326 women, 3 had positive pregnancy tests and were ultimately confirmed to be pregnant. Although all 3 women denied the possibility of pregnancy prior to testing, 2 had been unable to give an exact date for their last menstrual period (LMP). CONCLUSIONS In this group of 326 northern New England HCWs being immunized against measles during an outbreak, history taking alone failed to identify 3 pregnancies. If the inability to give an exact date of the LMP had been included as a discriminator, 2 additional pregnancies could have been suspected, but 1 pregnancy still would have gone undetected.