Low birthweight in New York City and upstate New York following the events of September 11th.

BACKGROUND We examined pregnancy outcomes in New York City (NYC) and upstate New York after the September 11, 2001 World Trade Center disaster. METHODS Using birth certificate data for NY residents (n = 1,660,401 births), we estimated risk of low birthweight (LBW: <2,500 g) and preterm birth (<37 weeks) one week after September 11th versus three weeks before, and for 10 four-week intervals post-disaster versus these intervals in the two previous years. To corroborate regression results, we used time-series analysis. RESULTS One week after September 11th in NYC, we observed an adjusted odds of 1.44 for births <1,500 g (P = 0.07) and 1.67 for births 1,500-1,999 g (P = 0.01), but a decreased odds of 2,000-2,499 g. We found no immediate change in LBW upstate or preterm in either location. In extended analyses, we found, in both locations, increased odds of <1,500-g births around New Year and 33-36 weeks post-disaster and decreased odds of moderate preterm for several weeks post-disaster. Time-series analyses yielded similar findings. CONCLUSIONS The events of September 11, 2001 in NYC were associated with immediate increases in births <2,000 g, slightly delayed decreased preterm delivery, and delayed increases in LBW among infants exposed periconception or in the first two trimesters. Stress may contribute to observed associations.