Methods
Study design and
participants
This study was designed as an
observational cohort based on real-world data in two centers from March
2016 to December 2018. Pregnant women with twins who ‘booked’ at
the First Affiliated Hospital of
Chongqing Medical University were routinely offered prophylaxis with
low-dose aspirin (LDA group) before 16 weeks of gestational age and
those recruited from Chongqing Health Center for Women and Children were
not required to take aspirin and regarded as the control group (NC
group). This difference was based upon clinician preference at the two
institutions. In the LDA group, participants were administered aspirin
from the day when registered. Aspirin was taken at the dose of 100mg per
night from recruitment until 35 weeks of gestation age. Inclusion
criteria were: Twin pregnancies were diagnosed by ultrasound in the
first visit. Those who did not start their first antenatal care in the
two centers but delivered in these 2 hospitals were excluded in the
final analysis due to incomplete records of prior medications.
Pregnant women were asked to have
a visit every 2 weeks before 28 weeks of gestational age, and every 1
week when the gestational week was over 28.
Data collection
All
pregnant patient clinical, demographic, neonatal assessments, and
outcomes data during pregnancy and at delivery were recorded in the Case
Report Form (CRF). All the information was concurrently recorded in both
Hospital Information Systems (HIS) and Cohort Management Systems.
According to the medical records, each participant in the LDA group was
confirmed to have an over 90% drug compliance.