Study design
This is a case-control study to identify maternal risk
Study setting and participants
This case-control study was conducted in Chaiyaphum
Hospital. In general, preterm cases were diagnosed were
defined as pregnant women with a live preterm
baby(gestational age 28 to less than 37 weeks).
Unmatched controls were defined as pregnant women
with a full-term live birth (gestational age 37 weeks or
more) without malformations at Chaiyaphum Hospital
between January 2006 and December 2010.