Trends in marriage and fertility

BlogDec 16 2011

New federal data on births and marriages shed some light on high levels of births outside of marriage in the U.S.[1]  A research brief from Child Trends, Childbearing Outside of Marriage: Estimates and Trends in the United States, documents that 41% of all births in 2009 were outside of marriage.  This percentage rises to more than half (53%) of all births to women under age 30.[2]  Part of the reason for high numbers and rates of nonmarital births is due to increases in the median age at marriage.  Currently, the median age at first marriage – the age at which half of all women get married for the first time– is a year older than the median age at first birth.[3],[4] The Pew Charitable Trusts reports the median age at marriage is 26 for women, while recent birth data shows the median age at first birth is age 25.[5],[6]  These numbers reflect greater delays in marriage than in births in the past several decades.  For comparison, in 1980, the median age at marriage was one year younger than the median age at birth (at age 22 vs. age 23).[7],[8]

These trends in marriage and fertility have important implications for children. Their likelihood of being born to unmarried parents has increased from 18% in 1980 to current levels of 41%.[9],[10]  The large proportion of children that are born outside of marriage face challenges due to their greater likelihood of growing up in poverty and with family instability, leading to greater cognitive and behavioral problems, such as aggression and depression.[11]

While more than half of these nonmarital births (52%) occur to women who live with the father of the baby in a cohabiting union,[12] these unions are less stable than marriages.[13] Children born to unmarried parents are more likely than those born to married parents to be poor and to see their parents’ union end.[14]


[1] Hamilton, B.E., Martin, J.A., Ventura, S.J. (2011). Births: Preliminary Data for 2010. National Vital Statistics Reports 60(2). Hyattsville, MD: National Center for Health Statistics.http://www.cdc.gov/nchs/data/nvsr/nvsr60/nvsr60_02.pdf

[2] Berger, A. (2011). Child Trends’ analysis of National Vital Statistics System birth data. Washington, DC: Child Trends.

[3] U.S. Census Bureau, Current Population Survey, March and Annual Social and Economic Supplements. http://www.census.gov/population/socdemo/hh-fam/ms2.pdf

[4] Mathews TJ, Hamilton BE. Mean age of mother, 1970–2000. National vital statistics reports; vol 51 no 1. Hyattsville, Maryland: National Center for Health Statistics. 2002. http://www.cdc.gov/nchs/data/nvsr/nvsr51/nvsr51_01.pdf

[5] Taylor, P., Parker, K., Cohn, D., Passel, J.S., Livingston, G., Wang, W., Patten, E. (2011) Barely half of U.S. adults are married- a record low. Washington D.C.: Pew Research Center. http://www.pewsocialtrends.org/files/2011/12/marriage-decline-final.pdf

[6] Berger, A. (2011). Child Trends’ analysis of National Vital Statistics System birth data. Washington, DC: Child Trends.

[7] U.S. Census Bureau, Current Population Survey, March and Annual Social and Economic Supplements. http://www.census.gov/population/socdemo/hh-fam/ms2.pdf

[8] Mathews TJ, Hamilton BE. Mean age of mother, 1970–2000. National vital statistics reports; vol 51 no 1. Hyattsville, Maryland: National Center for Health Statistics. 2002. http://www.cdc.gov/nchs/data/nvsr/nvsr51/nvsr51_01.pdf

[9] Ventura, S. J., & Bachrach, C. A. (2000). Nonmarital childbearing in the United States, 1940-1999.  National Vital Statistics Reports (vol 48, no. 16). Hyattsville, MD: National Center for Health Statistics. http://www.cdc.gov/nchs/data/nvsr/nvsr48/nvs48_16.pdf

[10] Wildsmith, E., Steward-Streng, N. R., & Manlove, J. (2011). Childbearing outside of marriage: Estimates and trends in the United States. Washington, D.C.: Child Trends. https://www.childtrends.org/Files/Child_Trends-2011_11_01_RB_NonmaritalCB.pdf

[11] McLanahan, S. (2011). Family instability and complexity after a nonmarital birth: Outcomes for children in fragile families. In M. J. Carlson, & P. England (Eds.), Social class and changing families in an unequal America. Stanford: Stanford University Press.

[12] Wildsmith, E., Steward-Streng, N. R., & Manlove, J. (2011). Childbearing outside of marriage: Estimates and trends in the United States. Washington, D.C.: Child Trends. https://www.childtrends.org/Files/Child_Trends-2011_11_01_RB_NonmaritalCB.pdf

[13] McLanahan, S. (2011). Family instability and complexity after a nonmarital birth: Outcomes for children in fragile families. In M. J. Carlson, & P. England (Eds.), Social class and changing families in an unequal America. Stanford: Stanford University Press.

[14] McLanahan, S. (2011). Family instability and complexity after a nonmarital birth: Outcomes for children in fragile families. In M. J. Carlson, & P. England (Eds.), Social class and changing families in an unequal America. Stanford: Stanford University Press.

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