Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Flow diagram of selected participants. ¹See online supplemental material for more information on how we dealt with uncertain pregnancies in the Clinical Practice Research Datalink Pregnancy Register. ²Conflicting pregnancies refer to pregnancies where dates overlap. ³Historical pregnancies refer to past pregnancies recorded at a later date. HES, Hospital Episode Statistics.
