Protocol, eligibility criteria, information sources and search
This systematic review was performed
and conducted following the PRISMA30 and
MOOSE31 guidelines, which were
recommended standards for systematic
reviews and meta‐analysis. PubMed, Embase, Web of Science and Cochrane
Library were searched systematically for relevant studies from
establishment until July 2021, combining relevant medical subject
heading terms, key words and word variants for “hypertension” or
“hypertensive” or “preeclampsia” or “preeclamptic” or
“eclampsia” or “eclamptic” and “birthweight” and “discordance”
or “discordant” and “twin pregnancies” (Appendix S1).
The
search and inclusion criteria were restricted to human data and English
language. Additional reports were manually searched by two authors (YW,
HYZ) according to the reference lists of selected articles and reviews.