Definition
Pre-pregnant body mass index (pre-BMI) was calculated as dividing the
pre-pregnant body weight (kilograms) by the square of height (meters),
and classified into underweight (<18.5
kg/m2), normal
weight (18.5-22.9 kg/m2) and overweight/obesity (≥23
kg/m2) based on the Asia-Pacific classification of
BMI5.
According to the diagnostic criteria, which was founded by the Chinese
Medical Association in 2014, GDM was diagnosed when any serum glucose
value equaled or exceeded the thresholds during OGTT:fasting blood
glucose (FBG), 5.1 mmol/l; 1 hour, 10.0mmol/l; and 2 hour, 8.5mmol/l.
However, FBG≥7.0mmol/l or 2 hour
result≥ 11.1mmo/l was considered as pre-gestational diabetes mellitus
(PGDM), and then excluded from our study6.
Gestational hypertension was defined as new-onset hypertension (systolic
blood pressure≥140 mmHg and/or diastolic blood pressure≥90 mmHg) after
20 weeks of gestation in the absence of proteinuria, which returned to
normal within 12 weeks after delivery7. PE was the
progression of GH, which was defined as new-onset hypertension with
albuminuria (≥ 0.3g protein of urine in 24 hours or positive detection
of random urine protein) or other biochemical or haematological
abnormalities.
Postpartum hemorrhage was defined by the
International
Federation of Gynecology and Obstetrics 8 criteria (24
hours postpartum bleeding ≥ 500 ml in vaginal delivery; ≥ 1000 ml in
caesarean delivery).
Small for gestational age (SGA) was
defined as neonatal birth weight less than the 10thpercentile for gestational age, while LGA was above the
90th percentile; both of them were based on the
Chinese
Neonatal Birth Weight Curve for Different Gestational
Age9. PTB was defined as gestational age at delivery
smaller than 37 weeks10.