First of all, you did nothing wrong. This is a very common condition that affects many women. No, you do not have to stop exercising and no you did not permanently destroy your ab muscles. Yes, after the baby comes you will be able to "repair" it with the appropriate exercises.
A very good reference for this is "Essential Exercises for the Childbearing Year" by Elizabeth Noble. I would highly recommend this book.
Also, here is an exerpt from my "Healthy Moms Perinatal Fitness Instructor Training Manual"
Diastasis Recti
As a quick review, the rectus abdominis is the outermost abdominal muscle, which attaches from the top of the ribs to the pubic bone. It is composed of two halves called recti that are normally about a half an inch apart. The two recti are joined by a fibrous band of connective tissue or central seam known as the linea alba. The hormones of pregnancy cause the linea alba to soften. This is why women notice a “thicker” waistline early in their pregnancies. This softening coupled with the increased pressure from the growing baby may actually cause the two recti to separate around the area of the navel, somewhat like a zipper separating under stress. The onset of diastasis recti may be gradual or sudden (Ex. During a bout of coughing or during labor). During pregnancy, a gap or bulge is often noticed in the seam when the head and shoulders are raised. This is the “telltale” sign of a diastasis. Women sometimes find their diastases when they are rising out of bed and notice the bulge.
Implications
Pregnant women should be checked for separation after the 20th week of pregnancy or when they begin to “show.” They should be checked every one to two weeks after their initial assessment. Clients should also be checked after they return to class postpartum since they may have separated during labor and delivery.
The oblique muscles, which are involved with trunk rotation, insert into the linea alba. If a mom has a separated rectus muscle, she should not be doing rotational oblique work as this could encourage further separation. It is necessary to “splint” the seam (i.e. the “corrective” exercise) by crossing the hands over the lower abdomen when doing abdominal work.
Separation Check
POSITION: Supine, knees bent. Press fingers of one hand (horizontally) firmly into area around navel (perpendicular to the linea alba)
ACTION: Client slowly raises head and shoulders about 8 inches off the floor while reaching for her knees.
CHECK: How many fingers remain in gap?
- A slight gap (~ ½ - 1 finger) is normal.
- ~ 2 or more finger separation: Client should do the corrective exercise below.
"Corrective Exercise"
POSITION: Supine with knees bent(first trimester) or on a slight incline (after first trimester). Cross hands over the abdominal area and guide the recti muscles toward the midline to stabilize them.
ACTION: Inhale deeply. Slowly exhale and pull in abdominal muscles (“pull navel to spine”) while simultaneously pulling the underlying muscles together with your hands. Only raise your head, not your shoulders. Return to starting position.
This exercise should be done a few times in the morning and evening while lying in bed to keep the recti muscles in maximum tone and to discourage further separation.
