Multivariable analysis of the step and slope per annum changes in pregnancy outcomes from 1 January 2006 referent to the underlying trend.

Data are step changes at 1 January 2006, and slope changes after 1 January 2006. Data adjusted for maternal age, infant sex, deprivation quintile, week of conception, number of previous spontaneous abortions, number of previous therapeutic abortions, and parity.aIncludes current, never, and former smokers and unknown smoking status.