TTTS:	Twin-to-twin transfusion syndrome
FLT	Fetal laser therapy
SAD	Serial amniondrainage
ART	Assisted reproductive techniques
DVP	Deepest vertical pocket
sIUD	Single intrauterine death
OPS	Operation and procedure classification codes
CI	Confidence interval
ANOVA	Analysis of variance
HSD	Honest significant difference
WSS	Within-cluster sum of squares
SD	Standard deviation
LR	Likelihood ratio
MP	Multiple pregnancies
TAPS	Twin anemia–polycythemia sequence
IVF	In vitro fertilization
MZT	Monozygotic twinning