Compared with women having planned births, those who have unplanned births are less likely to recognize their pregnancy early, to receive early prenatal care or to breast-feed, and are more likely to have low-birth-weight babies, according to "Pregnancy Intentions, Maternal Behaviors and Infant Health: Investigating Relationships with New Measures and Propensity Score Analysis," by Kathryn Kost and Laura Lindberg. The study examines the associations between U.S. mothers’ pregnancy intentions, their pregnancy-related health behaviors and their infants’ health at birth.

"Almost 40% of the four million annual births in the United States result from an unintended pregnancy," says study author Kathryn Kost. "Our study found that births from unintended pregnancies are disadvantaged relative to births from intended ones. During and immediately following pregnancy, women with unplanned births are less likely to receive early prenatal care or to breast-feed the infant and are more likely to have infants with poorer health at birth. Enabling women to prevent an unintended pregnancy is a way to improve the health of children."

Data for the study come from women surveyed in the 2002 and 2006–2010 National Surveys of Family Growth, conducted by the National Center for Health Statistics. The analysis was limited to live births, and those resulting from unintended pregnancies were divided into three categories: mistimed (by less than two years), greatly mistimed (by more than two years) and unwanted.

The authors found that compared with planned births, among each type of unplanned birth, mothers were significantly younger; less likely to be married; and more likely to be cohabiting, to have had the delivery paid by Medicaid and to themselves have mothers who had less than a high school education, Births to black mothers had poorer outcomes than those to white mothers, and greatly mistimed or unwanted births were more likely than planned births to be among mothers who had not graduated from high school.

The study’s findings support concerns that greatly mistimed and unwanted births face considerable disadvantage, compared with wanted and well-timed births. The authors recommend that future research explore the characteristics and circumstances of mothers having unwanted and mistimed births to gain a better understanding of their particular constraints and hardships. Additionally, they suggest that public policy should focus on providing women and men with the services and support they need to avoid unintended pregnancies and empower them to choose the time and circumstances in which they bear a child.

"Pregnancy Intentions, Maternal Behaviors and Infant Health: Investigating Relationships with New Measures and Propensity Score Analysis," by Kathryn Kost and Laura Lindberg, is currently available online and will appear in the February 2015 issue of the journal Demography.

For a Guttmacher analysis of how this issue plays out in Oklahoma, please see "Pregnancy intentions and maternal and child health: an analysis of longitudinal data in Oklahoma," by Laura Lindberg, Isaac Maddow-Zimet, Kathryn Kost and Alicia Lincoln, published online in Maternal and Child Health Journal in October, 2014.