NewbornLow birth weights among babies born in and around New York City in the weeks and months after the terrorist attacks on the World Trade Center may be a result of a stress disorder.

Professor Brenda Eskenazi and colleagues studied data from birth certificates of 1,660,401 babies born in New York between January 1996 and December 2002.

They divided the babies into those born in New York City (NYC) – whose mothers would, therefore, have been living closest to the disaster zone – and those born in “upstate” New York, which they defined as anyone living outside NYC.

When they compared data from babies born in the week before the disaster with those born in the week after in NYC, they found a shift in the distribution of low birth weights (LBW), with a higher proportion of babies being born weighing less than 2,000g. “Normal” birth weight is considered to be above 2,500g.

The study is published in the journal Human Reproduction.

Prof Eskenazi said: “In New York City in the week after 9/11 we found there was a slightly increased risk (44 percent) of new-born babies weighing below 1,500g and a 67 percent increased risk of babies weighing between 1,500g and 1,999g compared with the three weeks before the disaster. There were no statistically significant changes in any LBW category in upstate NY, or in babies being born preterm in either location.”

However, there was non-statistically significant evidence that the increase in LBW in the first week after 9/11 was due to babies being born early.

Gestational age data were provided to researchers in relatively broad categories which limited a more detailed investigation.

Overall, moderately pre-term births (32-36 weeks) were reduced in both areas for the first month post-9/11.

“We think that probably the most vulnerable foetuses were miscarried or born prematurely in that first week after 9/11, leaving behind those who were the strongest,” said Prof Eskenazi. “Another possibility is that one response to stress might be to ‘hold onto’ the foetus and to deliver later.”

Source: European Society for Human Reproduction and Embryology