The impact of fetal gender on prematurity in dichorionic twin gestations after in vitro fertilization.
BACKGROUND
Impact of fetal gender on prematurity has been primarily investigated in singleton pregnancies. In an attempt to understand better how fetal gender may affect gestational length in twin gestations after in vitro fertilization, same-sex twins and opposite twins were compared for pregnancy duration.


METHODS
This study evaluated 113 women at ages 20 to 39 years with consecutive dichorionic-diamniotic twin gestations after assisted reproduction. All pregnancies were results of fresh in vitro fertilization (IVF) cycles with use of autologous oocytes and sperm and were delivered at up to 37 weeks of gestation at a University-based high-risk, maternal-fetal medicine unit.


RESULTS
Both groups did not differ in baseline characteristics, such as maternal ages, indications for fertility treatments, number of previous IVF attempts, body mass index and parity. Opposite sex- twins, however, presented with significantly shorter gestational age at birth (32.9 +/- 3.4 weeks) than same-sex twins (34.3 +/- 2.5 weeks), (p < 0.05). Younger maternal age was also associated with shorter pregnancy duration (p < 0.05).


CONCLUSIONS
Fetal gender mix serves as risk factor for more significant prematurity in dichorionic-diamniotic twins after assisted reproduction with opposite sex twins at higher risk than same sex-twins.
Department of Obstetrics & Gynecology, Medical University Vienna, Vienna, Austria. andrea.weghofer@meduniwien.ac.at
Andrea
A
Weghofer
Katharina
K
Klein
Maria
M
Stammler-Safar
Christof
C
Worda
David H
DH
Barad
Peter
P
Husslein
Norbert
N
Gleicher
D000328:Adult; D005260:Female; D005307:Fertilization in Vitro / Q000706:statistics & numerical data; D005333:Fetus / Q000502:physiology*; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature / Q000502:physiology; D008297:Male; D008431:Maternal-Fetal Exchange / Q000502:physiology; D007752:Obstetric Labor, Premature / Q000453:epidemiology / Q000209:etiology*; D011247:Pregnancy; D011272:Pregnancy, Multiple / Q000502:physiology* / Q000706:statistics & numerical data; D012307:Risk Factors; D012737:Sex Factors; D014429:Twins, Dizygotic; D055815:Young Adult