Introduction
The prevalence of twin pregnancy is increasing, primarily as a result of
the use of Assisted Reproductive Technologies (ART). Relative to
singletons, twin pregnancies are associated with increased maternal and
perinatal mortality and morbidity, the associated perinatal adverse
outcomes, including preeclampsia (PE),
small for gestational age (SGA)
babies, and preterm birth
(PTB).1 Recently, it has
been reiterated that the incidence of PE in twin pregnancies is 3-4
times folds higher compared to
singletons.2 A clinical
cohort study containing 321 twin pregnancies demonstrated the incidence
of at least one twin with birthweight <10thcentile was 47%, while at least one with birthweight
<5th centile was
27%.3 It is also
reported that the percentage of PTB in twin pregnancies is significantly
higher than singletons, with 50-60% delivering prior to 37
weeks.4 The increasing
morbidity and mortality associated with adverse pregnancy outcomes of
PTB, PE, and SGA remain major concerns internationally. Although the
etiology of these complications has yet been fully elucidated, their
development is generally associated with increased inflammation and/or
hypoxia.5-8
The well-described anti-inflammatory and anti-coagulation properties of
aspirin have made it an appealing target for preventing
gestational hypertensive disorders, but the specific mechanism is still
unclear.9 According to
recent studies, we have a better understanding of the effects of aspirin
on the prophylaxis of PE, PTB, and
SGA.10-12 Based on
current data, the American College of Obstetricians and Gynecologists
(ACOG) recommends daily low-dose aspirin (81mg/day) in pregnancy to
prevent adverse outcomes and while not increasing the risk of postpartum
hemorrhage.13 But
another meta-analysis14concluded that a dose of aspirin between 100-150mg was more beneficial,
especially if initiated before 16 weeks. However, the optimal dose has
not reached a consensus. Unlike in singletons, few studies have explored
the potential beneficial (or otherwise) effects of aspirin in twin
pregnancies. The ACOG-guideline recommended pregnant women to take
aspirin based on circumstantial evidence – according to the incidence
of PE was much higher in twin
pregnancies.13 But
there is a relative lack of direct evidence whether aspirin could reduce
these adverse outcomes in twin pregnancies.
Given the limited data on twin pregnancies and the often conflicting
results in singleton pregnancies, we undertook an observational cohort
study based on real-world data. We aimed to explore the potential
benefits of aspirin on twin pregnancies and provides a theoretical basis
for further researches.