have underweight, which was defined as pre-pregnancy
BMI less than 20 kg/m2
. Exclusion criteria were women
who had medical disorder or any condition which may
affect pregnancy outcomes (e.g. pre-existing diabetes,
chronic hypertension, autoimmune disease, renal
disease, etc), drug abuse, smoking, alcohol drinking,
severe congenital anomaly or chromosomal abnormality,
incomplete data record, and non-Thai ethnicity. The
study was approved by the Vajira Institutional Review
Board (Registered Number 074/55).