PT - JOURNAL ARTICLE AU - Buekens, P AU - Delvoye, P AU - Wollast, E AU - Robyn, C TI - Epidemiology of pregnancies with unknown last menstrual period. AID - 10.1136/jech.38.1.79 DP - 1984 Mar 01 TA - Journal of Epidemiology and Community Health PG - 79--80 VI - 38 IP - 1 4099 - http://jech.bmj.com/content/38/1/79.short 4100 - http://jech.bmj.com/content/38/1/79.full SO - J Epidemiol Community Health1984 Mar 01; 38 AB - A group of women with unknown last menstrual period was studied representing 16% of a total of 22 404 pregnant women recorded using a common perinatal form. Unknown menstrual period is associated with high rates of low birth weight and with low socioeconomic and sociodemographic status. Such characteristics are also associated with a high rate of preterm deliveries. Thus any possible bias introduced in studies of prematurity by ignoring the group of women with unknown last menstrual period should be carefully checked.