46  American Association on Mental Retardation VOLUME 107, NUMBER 1: 46–59  JANUARY 2002 AMERICAN JOURNAL ON MENTAL RETARDATION Early Risk Factors for Mental Retardation: Role of Maternal Age and Maternal Education Derek A. Chapman Tennessee Department of Health (Nashville) Keith G. Scott University of Miami Craig A. Mason University of Maine Abstract The predictive value of maternal age and education in relation to rates of administratively defined mental retardation in a 3-year birth cohort (N = 267,277) was studied. Low ma- ternal education placed individuals at increased risk for both educable mentally handi- capped (EMH) and trainable mentally handicapped (TMH) placements. Older maternal age was associated with increased risk of mental retardation, but for individuals with EMH, this age effect was only seen in the lowest education group. In terms of population-level risk, it was younger mothers with 12 years of education or less whose births were associated with the greatest proportion of mental retardation. From a public policy viewpoint, chil- dren born to mothers with low levels of education are an important group to target for prevention/early intervention efforts. Over the past 25 years, childbearing practices have changed dramatically in the United States. The teenage birth rate has remained high (49.6 per 1,000 in 1999) despite a 20% reduction between 1991 and 1999 (Curtin & Martin, 2000). The birth rate among older women (ages 35 to 44 years) has risen steadily since 1980, while rates among wom- en ages 20 to 29 years have fallen (Williams & Decoufle ´, 1999). This trend of delayed childbear- ing, observed mainly for college-educated women, has been linked to lower first birth rates for wom- en in their 20s and much higher first birth rates among women in their 30s (Lewis & Ventura, 1990; Ventura, 1989). For example, 11% of pre- viously childless women with a college degree who ranged in age from 30 to 35 years gave birth in 1994 compared with only 4% of childless col- lege graduates ages 20 to 24 years (Mathews & Ventura, 1997). These age-related trends appear to have im- plications for the study of mental retardation. Teenage motherhood has been associated with in- creased risk for a number of health and develop- mental problems, including poor cognitive devel- opment (Furstenberg, Brooks-Gunn, & Chase- Lansdale, 1989; Moore & Snyder, 1991; Pianta, Lopez-Hernandez, & Ferguson, 1997; Wadsworth, Taylor, Osborn, & Butler, 1984) and low birth- weight, that is, less than 2,500 g (Lee, Ferguson, Corpuz, & Gartner, 1988; Reichman & Pagnini, 1997), which has been directly linked to mental retardation (Drews, Yeargin-Allsopp, Decoufle ´, & Murphy, 1995; McDermott, Coker, & McKeown, 1993; Mervis, Decoufle ´, Murphy, & Yeargin-All- sopp, 1995; Scott, 1988). Children born to women at the upper end of the age spectrum have also been found to be at increased risk for mental retardation. Risk for Down syndrome, the most common chromosom- al abnormality and the largest single cause of se-