Study design
This retrospective study included 2,586 pregnant women delivering twins
between 2005 and 2020 at the Buergerhospital in Frankfurt, Germany.
Thereof, 2,449 women fulfilled the two primary inclusion criteria,
diamnionicity and an available pre-pregnancy BMI (calculated as weight
[kg] divided by the square of height [m2]) and
were analyzed for maternal outcomes.
For the neonatal analysis, 246 twin pairs of mothers being analyzed were
excluded because of gestational age less than 24 weeks, stillbirth,
congenital malformation, twin-to-twin transfusion syndrome, twin anemia
polycythemia sequence, medically indicated abortions and hospitalization
for less than 72 hours after birth.
The mothers were subdivided according to their pre-pregnancy BMI based
on WHO standards (underweight <18.5 kg/m2,
normal weight 18.5 – 24.9 kg/m2, overweight 25 –
29.9 kg/m2, obese ≥30 kg/m2, obesity
class I 30 – 34.9 kg/m2, obesity class II 35 –
39.9 kg/m2 and obesity class III
≥40 kg/m2). The obese group consisted of 265 women,
whereof 171 were in obesity class I, 58 in obesity class II and 36 in
obesity class III.