Methods
Secondary routine healthcare data was retrieved from women with their
first two consecutive deliveries from January 2015 to September 2020 at
the KK Women’s and Children’s Hospital (KKH), Singapore. KKH houses the
largest public maternity unit in Singapore and manages one-third of all
live births in this country with approximately 12,000 deliveries every
year, across a wide sociodemographic spectrum. We retrospectively
extracted electronic medical records of women who had singleton births
at 24 weeks gestation or more in the first and second pregnancies. Only
women who were 21 years or older and conceived naturally in the first
and second pregnancies were included. Women with missing information
about BMI (at first and/ or second pregnancies) and interpregnancy
interval were excluded. Ethical approval was obtained from the
Centralised Institutional Review Board of SingHealth (reference
2020/2018).