The impact of medically indicated and spontaneous preterm birth among hypertensive women.

Objective  To (1) describe the frequency of spontaneous preterm birth (SPTB) and medically indicated preterm birth (PTB) among women with chronic hypertension (CHTN) and (2) to evaluate differences in neonatal outcomes according to SPTB or medically indicated PTB. Study Design  Retrospective analysis of a previously conducted multicenter randomized trial. Deliveries were categorized as SPTB or medically indicated and stratified by gestational ages ( 6/7 weeks, 30 to 33 6/7 weeks,  Results  Of 765 women, 32.2% ( n  = 246) delivered at  n  = 80) were SPTB and 21.6% ( n  = 166) were medically indicated. Fifty-nine percent of PTBs occurred in the late preterm period ( n  = 146). SGA was significantly more frequent among those with medically indicated PTB at  p  = 0.03). There were no other differences in adverse neonatal outcomes between medically indicated versus SPTB at any gestational age ( p  > 0.05). Conclusion  Nearly one-third of women with CHTN delivered preterm. The majority of PTBs were medically indicated and late preterm, but approximately one-third were due to SPTB.