Preterm birth and selection in utero among males following the November 2015 Paris attacks

On 13 November 2015, coordinated terrorist attacks swept through Paris. This large stressor, like earlier terrorist attacks in the USA, may have perturbed the health of pregnant women. We test whether the attacks preceded an increase in the risk of preterm parturition among live-born males as well as excess male loss in utero. We focused on males on the basis of previous findings of elevated male frailty following population stressors.

We examined live births in the Paris region (n = 1 049 057) over 70 months, from January 2011 to October 2016. Interrupted time-series methods identified and removed serial correlation in the monthly risk of preterm birth; these methods employed non-linear least-squares estimation. We also repeated analyses using month of conception, and performed sensitivity tests among females as well as among male births outside Paris.

Males exhibited an elevated incidence of preterm birth in November 2015 and January 2016 [risk difference for November 2015 = 0.006, 95% confidence interval (CI): 0.0002-0.012; risk difference for January 2016 = 0.010, 95% CI: 0.004-0.016], which equates to an 11% increase in the count of preterm births. Females, as well as males born outside Paris, showed no change in preterm delivery. The sex ratio also fell below expected values in December 2015, January 2016 and February 2016.

Among males, more preterm births, but fewer live births, occurred after the November 2015 Paris attacks. Future examinations of perinatal health responses to unexpected stressors may benefit from sex-specific analyses.