This particular myth seems to stem from the recommendation that pregnant women should not lie on their backs for extended periods of time after the first trimester.
In an earlier post, I explained that around the 12-16 week mark (though it can be much later for some), a woman’s uterus becomes large enough that when she lies flat on her back, it may exert pressure on the vena cava — the vein responsible for returning blood from the lower body to the heart. This is believed to interfere with the flow of blood and nutrients to the placenta, with the implication being that it could be harmful to the developing fetus.
According to obstetrician Dr. Michael S. Broder, author of The Panic-Free Pregnancy, this reduction in blood flow to the placenta is “a laboratory finding only,” and has never been medically correlated with any increased risk to the fetus. In fact, even the American College of Obstetricians and Gynaecologists only cautions against extended periods of supine lying. So while sleeping on your back for an entire night might not be advisable, a few minutes here and there is not likely to be harmful.
That said, some pregnant women report orthostatic hypotension (a “head rush”) upon rising from a supine position, and in that case, it is most certainly better to err on the side of caution and avoid it altogether. The key with all things pregnancy-related is to listen to the body. If it doesn’t feel good, don’t do it!
So where does this leave us with sit-ups? Well, unless you are Superwoman, chances are that you don’t do sit-ups for more than a couple of minutes at a time before your abs are screaming for a break. As long as you take care to rest between sets in any position other than flat on your back, short sets of sit-ups are absolutely not going to harm your baby.
As well, once your abdominal area begins to enlarge, the compression action of sit-ups will become increasingly uncomfortable, probably to the point where you will no longer want to perform them. I certainly noticed last week that V-sit-ups were difficult and uncomfortable, and I had to modify them by bending my legs at the knees. I am pretty sure that within the next few weeks, I will find that even regular sit-ups will start to become uncomfortable.
At that point, I will switch to alternative abdominal exercises such as knees-to-elbows (for as long as I can safely and comfortably do them), L-sits, front and side planks, and overhead squats (which are fantastic for working stabilizer muscles).
I think my midwife said it best when she said, “If you feel comfortable doing sit-ups, do them. Your body will tell you when it’s time to stop.”
Rounds in 20 min:
5 chest-to-bar pull-ups (had to use the 1/2 inch band for these)
9 seconds of L-sit (I did a modified bent-knee version)
Total: 7 rounds + 3 pull-ups
Chest-to-bar pull-ups are certainly difficult with even just a few extra pounds on me! I did the first couple with no band, but then realized I just wasn’t going to be able to get any significant numbers without some assistance. Same goes for the L-sits — I just didn’t seem to have the abdominal strength to hold them with straight legs. Ah well…