Lower embryonic loss rates among twin gestations following assisted reproduction.
OBJECTIVE
To determine whether maternal age and number of transferred embryos influence early pregnancy losses in twin pregnancies compared to singletons following IVF/ICSI.


METHODS
We compared the pregnancy loss rates in singleton (n = 549) and twin (n = 252) gestations, stratified by maternal age (< or = 35 and > 35 years) and the number of transferred embryos (1-3 and 4-9).


RESULTS
Loss rates of singleton pregnancies were significantly higher than that in twins (OR 3.0, 95% CI 1.9, 4.9), especially among singletons conceived after transfer of 4-9 embryos (OR 5.0, 95% CI 2.2, 11.9). Younger mothers of twins had lower loss rates (OR 0.3, 95% CI 0.1, 0.9).


CONCLUSIONS
Twins have a significantly reduced spontaneous miscarriage rate compared with singletons following IVF/ICSI. Higher implantation rates per cycle (i.e., development of twins rather than one live embryo) may represent a better capacity of the uterus for early embryonic development.
La Sala
G B
GB
Department of Obstetrics and Gynecolgy, Arcispedale Santa Maria Nuova, Reggio Emilia, Italy.
Nucera
G
G
Gallinelli
A
A
Nicoli
A
A
Villani
M T
MT
Blickstein
I
I
D000022:Abortion, Spontaneous / Q000209:etiology*; D000328:Adult; D047108:Embryonic Development / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008423:Maternal Age; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011272:Pregnancy, Multiple; D011446:Prospective Studies; D020554:Sperm Injections, Intracytoplasmic / Q000009:adverse effects*; D014427:Twins