Trends in maternal characteristics, low birth weight (LBW) and preterm birth (PTB) rates among U.S. non-Hispanic Black women, 1991 - 2004

Reducing LBW and PTB rates among non-Hispanic Black (NHB) women has been a clinical and public health priority for over two decades. Simultaneously, changes in demographics, health status and care use, and social programs occurred which potentially affected this population and outcomes.

We analyzed changes in LBW, moderate LBW (MLBW), very LBW (VLBW), and PTB rates from 1991 to 2004 for U.S. singleton live births to NHB women. We conducted cross-sectional and trend analyses using Joinpoint, stratified, and binomial regression methods. In comparing variables other than outcomes between 2003 or 2004 and earlier years, analyses were restricted to States using the 1989 birth certificate revision.

We identified a change in trend in 2001. LBW rates declined from 12.15% in 1991 to 11.19% in 2001 and then increased to 11.70% in 2004. PTB trends resembled those for LBW. The LBW trend was explained by the MLBW trend: 9.60% in 1991; 8.62% in 2001; 9.10% in 2004. VLBW did not follow this pattern, minimally increasing from 1991-2001 and then remaining relatively stable through 2004. In adjusted models, the 1991-2001 MLBW decrease was explained by increases in 1st trimester prenatal care, foreign-born mothers, maternal education and weight gain and reductions in smoking. The 2001-2004 MLBW increase remained independent of changes in demographics, prenatal care, obstetric history, and obstetric interventions. The effects of education, as a marker for socioeconomic status, and of social policy changes on outcomes are explored. To achieve Healthy People 2010 goals, continued risk reduction among NHB women remains a priority.