Background Since 1991, multiple births have increased sharply in the United States. During the same period, rates of low birthweight and preterm births have also increased, particularly among white infants. Infants born as part of a multiple birth are more likely to be low birthweight and/or preterm. Methods A population-based analysis was performed using US natality data from 1991, 1994, and 1997. White and black infants with complete records were included in analysis. Four outcomes of interest were measured using a bivariate classification of gestational age and birthweight. The strength of the association between plurality and outcome was determined with polyotomous logistic regression. Year of birth and maternal age (<35, 35+) modified the effect of plurality on outcome and the data were stratified accordingly. Results Odds ratios for preterm births increased each year among white infants. Among younger white women the ORs for preterm/low birthweight births increased 23% (34.0 to 41.9) compared to a 32% increase among older mothers (24.2 to 32.0). The ORs for white preterm/normal birthweight births increased 24% among younger women (5.9 to 7.3) compared to 16% among older women (5.8 to 6.7). Among black mothers, ORs for births in the preterm categories increased for younger mothers only. Conclusions As multiple births continue to increase in the US, it is important to recognize their impact on infant outcome. The increasing differences in risk of adverse outcomes between singletons and infants born as part of a multiple birth illustrate a growing public health concern in the United States.
Learning Objectives: At the conclusion of this presentation, the participant will be able to: 1. Recognize the growing disparities in adverse outcomes between singletons and infants born as part of a multiple birth 2. Understand the growing impact of multiple births on increasing low birth weight and preterm births 3. Discuss possible causes influencing increasing multiple births and adverse outcomes
Keywords: Low Birthweight, Infant Health
Presenting author's disclosure statement:
Organization/institution whose products or services will be discussed: None
I do not have any significant financial interest/arrangement or affiliation with any organization/institution whose products or services are being discussed in this session.