I would assume they relax and stretch along with the uterus, since the uterus is a muscle as well. In certain cases though you can have a diastasis recti which is when the most outer layer of muscle splits in the middle and this can cause what looks like a valley in the abs later on after baby is born.
The Eastern Time (ET) or Eastern Standard Time (EST) is also known as North American Eastern Standard Time. It is the time zone that pertains to the east coast of North America. The clock time in the Eastern Time is based on the mean solar time of the 75th meridian west of the Greenwich Observatory in London.
Eastern Standard Time (EST) is 5 hours behind Coordinated Universal Time (UTC) . This time zone is a standard time zone and is used in: North America, Caribbean, Central America. This time zone is often called Eastern Time Zone. See full time zone map.